//
// BluetoothMeshService.swift
// bitchat
//
// This is free and unencumbered software released into the public domain.
// For more information, see <https://unlicense.org>
//

import Foundation
import CoreBluetooth
import Combine
import CryptoKit
import os.log
#if os(macOS)
import AppKit
import IOKit.ps
#else
import UIKit
#endif

// Hex encoding/decoding is now in BinaryEncodingUtils.swift

// Extension for TimeInterval to Data conversion
extension TimeInterval {
    var data: Data {
        var value = self
        return Data(bytes: &value, count: MemoryLayout<TimeInterval>.size)
    }
}

// Version negotiation state
enum VersionNegotiationState {
    case none
    case helloSent
    case ackReceived(version: UInt8)
    case failed(reason: String)
}

// Peer connection state tracking
enum PeerConnectionState: CustomStringConvertible {
    case disconnected
    case connecting
    case connected         // BLE connected but not authenticated
    case authenticating    // Performing handshake
    case authenticated     // Handshake complete, ready for messages
    
    var isAvailable: Bool {
        switch self {
        case .authenticated:
            return true
        default:
            return false
        }
    }
    
    var description: String {
        switch self {
        case .disconnected: return "disconnected"
        case .connecting: return "connecting"
        case .connected: return "connected"
        case .authenticating: return "authenticating"
        case .authenticated: return "authenticated"
        }
    }
}

class BluetoothMeshService: NSObject {
    static let serviceUUID = CBUUID(string: "F47B5E2D-4A9E-4C5A-9B3F-8E1D2C3A4B5C")
    static let characteristicUUID = CBUUID(string: "A1B2C3D4-E5F6-4A5B-8C9D-0E1F2A3B4C5D")
    
    
    private var centralManager: CBCentralManager?
    private var peripheralManager: CBPeripheralManager?
    private var discoveredPeripherals: [CBPeripheral] = []
    private var connectedPeripherals: [String: CBPeripheral] = [:]
    private var peripheralCharacteristics: [CBPeripheral: CBCharacteristic] = [:]
    private var lastConnectionTime: [String: Date] = [:] // Track when peers last connected
    private var lastSuccessfulMessageTime: [String: Date] = [:] // Track last successful message exchange
    private var lastHeardFromPeer: [String: Date] = [:] // Track last time we received ANY packet from peer
    
    // Peer availability tracking
    private var peerAvailabilityState: [String: Bool] = [:]  // true = available, false = unavailable
    private let peerAvailabilityTimeout: TimeInterval = 30.0  // Mark unavailable after 30s of no response
    private var availabilityCheckTimer: Timer?
    
    private var characteristic: CBMutableCharacteristic?
    private var subscribedCentrals: [CBCentral] = []
    // Thread-safe collections using concurrent queues
    private let collectionsQueue = DispatchQueue(label: "bitchat.collections", attributes: .concurrent)
    private var peerNicknames: [String: String] = [:]
    private var activePeers: Set<String> = []  // Track all active peers
    private var peerRSSI: [String: NSNumber] = [:] // Track RSSI values for peers
    private var peripheralRSSI: [String: NSNumber] = [:] // Track RSSI by peripheral ID during discovery
    
    // Per-peer encryption queues to prevent nonce desynchronization
    private var peerEncryptionQueues: [String: DispatchQueue] = [:]
    private let encryptionQueuesLock = NSLock()
    
    // MARK: - Peer Identity Rotation
    // Mappings between ephemeral peer IDs and permanent fingerprints
    private var peerIDToFingerprint: [String: String] = [:]  // PeerID -> Fingerprint
    private var fingerprintToPeerID: [String: String] = [:]  // Fingerprint -> Current PeerID
    private var peerIdentityBindings: [String: PeerIdentityBinding] = [:]  // Fingerprint -> Full binding
    private var previousPeerID: String?  // Our previous peer ID for grace period
    private var rotationTimestamp: Date?  // When we last rotated
    private let rotationGracePeriod: TimeInterval = 60.0  // 1 minute grace period
    private var rotationLocked = false  // Prevent rotation during critical operations
    private var rotationTimer: Timer?  // Timer for scheduled rotations
    
    // MARK: - Identity Cache
    // In-memory cache for peer public keys to avoid keychain lookups
    private var peerPublicKeyCache: [String: Data] = [:]  // PeerID -> Public Key Data
    private var peerSigningKeyCache: [String: Data] = [:]  // PeerID -> Signing Key Data
    private let identityCacheTTL: TimeInterval = 3600.0  // 1 hour TTL
    private var identityCacheTimestamps: [String: Date] = [:]  // Track when entries were cached
    
    weak var delegate: BitchatDelegate?
    private let noiseService = NoiseEncryptionService()
    private let handshakeCoordinator = NoiseHandshakeCoordinator()
    
    // Protocol version negotiation state
    private var versionNegotiationState: [String: VersionNegotiationState] = [:]
    private var negotiatedVersions: [String: UInt8] = [:]  // peerID -> agreed version
    
    // MARK: - Write Queue for Disconnected Peripherals
    private struct QueuedWrite {
        let data: Data
        let peripheralID: String
        let peerID: String?
        let timestamp: Date
        let retryCount: Int
    }
    
    private var writeQueue: [String: [QueuedWrite]] = [:]  // PeripheralID -> Queue of writes
    private let writeQueueLock = NSLock()
    private let maxWriteQueueSize = 50  // Max queued writes per peripheral
    private let maxWriteRetries = 3
    private let writeQueueTTL: TimeInterval = 60.0  // Expire queued writes after 1 minute
    private var writeQueueTimer: Timer?  // Timer for processing expired writes
    
    // MARK: - Connection Pooling
    private let maxConnectedPeripherals = 10  // Limit simultaneous connections
    private let maxScanningDuration: TimeInterval = 5.0  // Stop scanning after 5 seconds to save battery
    
    func getNoiseService() -> NoiseEncryptionService {
        return noiseService
    }
    
    // MARK: - Identity Cache Methods
    
    func getCachedPublicKey(for peerID: String) -> Data? {
        return collectionsQueue.sync {
            // Check if cache entry exists and is not expired
            if let timestamp = identityCacheTimestamps[peerID],
               Date().timeIntervalSince(timestamp) < identityCacheTTL {
                return peerPublicKeyCache[peerID]
            }
            return nil
        }
    }
    
    func getCachedSigningKey(for peerID: String) -> Data? {
        return collectionsQueue.sync {
            // Check if cache entry exists and is not expired
            if let timestamp = identityCacheTimestamps[peerID],
               Date().timeIntervalSince(timestamp) < identityCacheTTL {
                return peerSigningKeyCache[peerID]
            }
            return nil
        }
    }
    
    private func cleanExpiredIdentityCache() {
        collectionsQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            let now = Date()
            var expiredPeerIDs: [String] = []
            
            for (peerID, timestamp) in self.identityCacheTimestamps {
                if now.timeIntervalSince(timestamp) >= self.identityCacheTTL {
                    expiredPeerIDs.append(peerID)
                }
            }
            
            for peerID in expiredPeerIDs {
                self.peerPublicKeyCache.removeValue(forKey: peerID)
                self.peerSigningKeyCache.removeValue(forKey: peerID)
                self.identityCacheTimestamps.removeValue(forKey: peerID)
            }
            
            if !expiredPeerIDs.isEmpty {
                SecureLogger.log("Cleaned \(expiredPeerIDs.count) expired identity cache entries", 
                               category: SecureLogger.session, level: .debug)
            }
        }
    }
    
    // MARK: - Write Queue Management
    
    private func writeToPeripheral(_ data: Data, peripheral: CBPeripheral, characteristic: CBCharacteristic, peerID: String? = nil) {
        let peripheralID = peripheral.identifier.uuidString
        
        // Double check the peripheral state to avoid API misuse
        guard peripheral.state == .connected else {
            // Queue write for disconnected peripheral
            queueWrite(data: data, peripheralID: peripheralID, peerID: peerID)
            return
        }
        
        // Verify characteristic is valid and writable
        guard characteristic.properties.contains(.write) || characteristic.properties.contains(.writeWithoutResponse) else {
            SecureLogger.log("Characteristic does not support writing for peripheral \(peripheralID)", 
                           category: SecureLogger.session, level: .warning)
            return
        }
        
        // Direct write if connected
        let writeType: CBCharacteristicWriteType = data.count > 512 ? .withResponse : .withoutResponse
        peripheral.writeValue(data, for: characteristic, type: writeType)
        
        // Update activity tracking
        updatePeripheralActivity(peripheralID)
    }
    
    private func queueWrite(data: Data, peripheralID: String, peerID: String?) {
        writeQueueLock.lock()
        defer { writeQueueLock.unlock() }
        
        // Check backpressure - drop oldest if queue is full
        var queue = writeQueue[peripheralID] ?? []
        
        if queue.count >= maxWriteQueueSize {
            // Remove oldest entries
            let removeCount = queue.count - maxWriteQueueSize + 1
            queue.removeFirst(removeCount)
            SecureLogger.log("Write queue full for \(peripheralID), dropped \(removeCount) oldest writes", 
                           category: SecureLogger.session, level: .warning)
        }
        
        let queuedWrite = QueuedWrite(
            data: data,
            peripheralID: peripheralID,
            peerID: peerID,
            timestamp: Date(),
            retryCount: 0
        )
        
        queue.append(queuedWrite)
        writeQueue[peripheralID] = queue
        
        SecureLogger.log("Queued write for disconnected peripheral \(peripheralID), queue size: \(queue.count)", 
                       category: SecureLogger.session, level: .debug)
    }
    
    private func processWriteQueue(for peripheral: CBPeripheral) {
        guard peripheral.state == .connected,
              let characteristic = peripheralCharacteristics[peripheral] else { return }
        
        let peripheralID = peripheral.identifier.uuidString
        
        writeQueueLock.lock()
        let queue = writeQueue[peripheralID] ?? []
        writeQueue[peripheralID] = []
        writeQueueLock.unlock()
        
        if !queue.isEmpty {
            SecureLogger.log("Processing \(queue.count) queued writes for \(peripheralID)", 
                           category: SecureLogger.session, level: .info)
        }
        
        // Process queued writes with small delay between them
        for (index, queuedWrite) in queue.enumerated() {
            DispatchQueue.main.asyncAfter(deadline: .now() + Double(index) * 0.01) { [weak self] in
                guard let self = self,
                      peripheral.state == .connected,
                      characteristic.properties.contains(.write) || characteristic.properties.contains(.writeWithoutResponse) else { 
                    return 
                }
                
                let writeType: CBCharacteristicWriteType = queuedWrite.data.count > 512 ? .withResponse : .withoutResponse
                peripheral.writeValue(queuedWrite.data, for: characteristic, type: writeType)
                
                // Update activity tracking
                self.updatePeripheralActivity(peripheralID)
            }
        }
    }
    
    private func cleanExpiredWriteQueues() {
        writeQueueLock.lock()
        defer { writeQueueLock.unlock() }
        
        let now = Date()
        var expiredWrites = 0
        
        for (peripheralID, queue) in writeQueue {
            let filteredQueue = queue.filter { write in
                now.timeIntervalSince(write.timestamp) < writeQueueTTL
            }
            
            expiredWrites += queue.count - filteredQueue.count
            
            if filteredQueue.isEmpty {
                writeQueue.removeValue(forKey: peripheralID)
            } else {
                writeQueue[peripheralID] = filteredQueue
            }
        }
        
        if expiredWrites > 0 {
            SecureLogger.log("Cleaned \(expiredWrites) expired queued writes", 
                           category: SecureLogger.session, level: .debug)
        }
    }
    private let messageQueue = DispatchQueue(label: "bitchat.messageQueue", attributes: .concurrent) // Concurrent queue with barriers
    private let processedMessages = BoundedSet<String>(maxSize: 1000)  // Bounded to prevent memory growth
    private let maxTTL: UInt8 = 7  // Maximum hops for long-distance delivery
    private var announcedToPeers = Set<String>()  // Track which peers we've announced to
    private var announcedPeers = Set<String>()  // Track peers who have already been announced
    private var hasNotifiedNetworkAvailable = false  // Track if we've notified about network availability
    private var lastNetworkNotificationTime: Date?  // Track when we last sent a network notification
    private var networkBecameEmptyTime: Date?  // Track when the network became empty
    private let networkNotificationCooldown: TimeInterval = 300  // 5 minutes between notifications
    private let networkEmptyResetDelay: TimeInterval = 60  // 1 minute before resetting notification flag
    private var intentionalDisconnects = Set<String>()  // Track peripherals we're disconnecting intentionally
    private var gracefullyLeftPeers = Set<String>()  // Track peers that sent leave messages
    private var peerLastSeenTimestamps = LRUCache<String, Date>(maxSize: 100)  // Bounded cache for peer timestamps
    private var cleanupTimer: Timer?  // Timer to clean up stale peers
    
    // Store-and-forward message cache
    private struct StoredMessage {
        let packet: BitchatPacket
        let timestamp: Date
        let messageID: String
        let isForFavorite: Bool  // Messages for favorites stored indefinitely
    }
    private var messageCache: [StoredMessage] = []
    private let messageCacheTimeout: TimeInterval = 43200  // 12 hours for regular peers
    private let maxCachedMessages = 100  // For regular peers
    private let maxCachedMessagesForFavorites = 1000  // Much larger cache for favorites
    private var favoriteMessageQueue: [String: [StoredMessage]] = [:]  // Per-favorite message queues
    private let deliveredMessages = BoundedSet<String>(maxSize: 5000)  // Bounded to prevent memory growth
    private var cachedMessagesSentToPeer = Set<String>()  // Track which peers have already received cached messages
    private let receivedMessageTimestamps = LRUCache<String, Date>(maxSize: 1000)  // Bounded cache
    private let recentlySentMessages = BoundedSet<String>(maxSize: 500)  // Short-term bounded cache
    private let lastMessageFromPeer = LRUCache<String, Date>(maxSize: 100)  // Bounded cache
    private let processedNoiseMessages = BoundedSet<String>(maxSize: 1000)  // Bounded cache
    
    // Battery and range optimizations
    private var scanDutyCycleTimer: Timer?
    private var isActivelyScanning = true
    private var activeScanDuration: TimeInterval = 5.0  // will be adjusted based on battery
    private var scanPauseDuration: TimeInterval = 10.0  // will be adjusted based on battery
    private var lastRSSIUpdate: [String: Date] = [:]  // Throttle RSSI updates
    private var batteryMonitorTimer: Timer?
    private var currentBatteryLevel: Float = 1.0  // Default to full battery
    
    // Battery optimizer integration
    private let batteryOptimizer = BatteryOptimizer.shared
    private var batteryOptimizerCancellables = Set<AnyCancellable>()
    
    // Peer list update debouncing
    private var peerListUpdateTimer: Timer?
    private let peerListUpdateDebounceInterval: TimeInterval = 0.1  // 100ms debounce for more responsive updates
    
    // Track when we last sent identity announcements to prevent flooding
    private var lastIdentityAnnounceTimes: [String: Date] = [:]
    private let identityAnnounceMinInterval: TimeInterval = 2.0  // Minimum 2 seconds between announcements per peer
    
    // Track handshake attempts to handle timeouts
    private var handshakeAttemptTimes: [String: Date] = [:]
    private let handshakeTimeout: TimeInterval = 5.0  // 5 seconds before retrying
    
    // Pending private messages waiting for handshake
    private var pendingPrivateMessages: [String: [(content: String, recipientNickname: String, messageID: String)]] = [:]
    
    // Cover traffic for privacy
    private var coverTrafficTimer: Timer?
    private let coverTrafficPrefix = "☂DUMMY☂"  // Prefix to identify dummy messages after decryption
    private var lastCoverTrafficTime = Date()
    
    // Connection state tracking
    private var peerConnectionStates: [String: PeerConnectionState] = [:]
    private let connectionStateQueue = DispatchQueue(label: "chat.bitchat.connectionState", attributes: .concurrent)
    
    // Protocol-level ACK tracking
    private var pendingAcks: [String: (packet: BitchatPacket, timestamp: Date, retries: Int)] = [:]
    private let ackTimeout: TimeInterval = 5.0  // 5 seconds to receive ACK
    private let maxAckRetries = 3
    private var ackTimer: Timer?
    private var advertisingTimer: Timer?  // Timer for interval-based advertising
    
    // Timing randomization for privacy
    private let minMessageDelay: TimeInterval = 0.01  // 10ms minimum for faster sync
    private let maxMessageDelay: TimeInterval = 0.1   // 100ms maximum for faster sync
    
    // Fragment handling with security limits
    private var incomingFragments: [String: [Int: Data]] = [:]  // fragmentID -> [index: data]
    private var fragmentMetadata: [String: (originalType: UInt8, totalFragments: Int, timestamp: Date)] = [:]
    private let maxFragmentSize = 469 // 512 bytes max MTU - 43 bytes for headers and metadata
    private let maxConcurrentFragmentSessions = 20  // Limit concurrent fragment sessions to prevent DoS
    private let fragmentTimeout: TimeInterval = 30  // 30 seconds timeout for incomplete fragments
    
    var myPeerID: String
    
    // ===== SCALING OPTIMIZATIONS =====
    
    // Connection pooling
    private var connectionPool: [String: CBPeripheral] = [:]
    private var connectionAttempts: [String: Int] = [:]
    private var connectionBackoff: [String: TimeInterval] = [:]
    private var lastActivityByPeripheralID: [String: Date] = [:]  // Track last activity for LRU
    private var peerIDByPeripheralID: [String: String] = [:]  // Map peripheral ID to peer ID
    private let maxConnectionAttempts = 3
    private let baseBackoffInterval: TimeInterval = 1.0
    
    // Probabilistic flooding
    private var relayProbability: Double = 1.0  // Start at 100%, decrease with peer count
    private let minRelayProbability: Double = 0.4  // Minimum 40% relay chance - ensures coverage
    
    // Message aggregation
    private var pendingMessages: [(message: BitchatPacket, destination: String?)] = []
    private var aggregationTimer: Timer?
    private var aggregationWindow: TimeInterval = 0.1  // 100ms window
    private let maxAggregatedMessages = 5
    
    // Optimized Bloom filter for efficient duplicate detection
    private var messageBloomFilter = OptimizedBloomFilter(expectedItems: 2000, falsePositiveRate: 0.01)
    private var bloomFilterResetTimer: Timer?
    
    // Network size estimation
    private var estimatedNetworkSize: Int {
        return max(activePeers.count, connectedPeripherals.count)
    }
    
    // Adaptive parameters based on network size
    private var adaptiveTTL: UInt8 {
        // Keep TTL high enough for messages to travel far
        let networkSize = estimatedNetworkSize
        if networkSize <= 20 {
            return 6  // Small networks: max distance
        } else if networkSize <= 50 {
            return 5  // Medium networks: still good reach
        } else if networkSize <= 100 {
            return 4  // Large networks: reasonable reach
        } else {
            return 3  // Very large networks: minimum viable
        }
    }
    
    private var adaptiveRelayProbability: Double {
        // Keep relay probability high enough to ensure delivery
        let networkSize = estimatedNetworkSize
        if networkSize <= 10 {
            return 1.0  // 100% for small networks
        } else if networkSize <= 30 {
            return 0.85 // 85% - most nodes relay
        } else if networkSize <= 50 {
            return 0.7  // 70% - still high probability
        } else if networkSize <= 100 {
            return 0.55 // 55% - over half relay
        } else {
            return 0.4  // 40% minimum - never go below this
        }
    }
    
    // BLE advertisement for lightweight presence
    private var advertisementData: [String: Any] = [:]
    private var isAdvertising = false
    
    // ===== MESSAGE AGGREGATION =====
    
    private func startAggregationTimer() {
        aggregationTimer?.invalidate()
        aggregationTimer = Timer.scheduledTimer(withTimeInterval: aggregationWindow, repeats: false) { [weak self] _ in
            self?.flushPendingMessages()
        }
    }
    
    private func flushPendingMessages() {
        guard !pendingMessages.isEmpty else { return }
        
        messageQueue.async { [weak self] in
            guard let self = self else { return }
            
            // Group messages by destination
            var messagesByDestination: [String?: [BitchatPacket]] = [:]
            
            for (message, destination) in self.pendingMessages {
                if messagesByDestination[destination] == nil {
                    messagesByDestination[destination] = []
                }
                messagesByDestination[destination]?.append(message)
            }
            
            // Send aggregated messages
            for (destination, messages) in messagesByDestination {
                if messages.count == 1 {
                    // Single message, send normally
                    if destination == nil {
                        self.broadcastPacket(messages[0])
                    } else if let dest = destination,
                              let peripheral = self.connectedPeripherals[dest],
                              let characteristic = self.peripheralCharacteristics[peripheral] {
                        if let data = messages[0].toBinaryData() {
                            self.writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: dest)
                        }
                    }
                } else {
                    // Multiple messages - could aggregate into a single packet
                    // For now, send with minimal delay between them
                    for (index, message) in messages.enumerated() {
                        let delay = Double(index) * 0.02  // 20ms between messages
                        DispatchQueue.main.asyncAfter(deadline: .now() + delay) { [weak self] in
                            if destination == nil {
                                self?.broadcastPacket(message)
                            } else if let dest = destination,
                                      let peripheral = self?.connectedPeripherals[dest],
                                      peripheral.state == .connected,
                                      let characteristic = self?.peripheralCharacteristics[peripheral] {
                                if let data = message.toBinaryData() {
                                    self?.writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: dest)
                                }
                            }
                        }
                    }
                }
            }
            
            // Clear pending messages
            self.pendingMessages.removeAll()
        }
    }
    
    // Removed getPublicKeyFingerprint - no longer needed with Noise
    
    // Get peer's fingerprint (replaces getPeerPublicKey)
    func getPeerFingerprint(_ peerID: String) -> String? {
        return noiseService.getPeerFingerprint(peerID)
    }
    
    // MARK: - Peer Identity Mapping
    
    // Update peer identity binding when receiving announcements
    func updatePeerBinding(_ newPeerID: String, fingerprint: String, binding: PeerIdentityBinding) {
        // Use async to ensure we're not blocking during view updates
        collectionsQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            var oldPeerID: String? = nil
            
            // Remove old peer ID mapping if exists
            if let existingPeerID = self.fingerprintToPeerID[fingerprint], existingPeerID != newPeerID {
                oldPeerID = existingPeerID
                SecureLogger.log("Peer ID rotation detected: \(existingPeerID) -> \(newPeerID) for fingerprint \(fingerprint)", category: SecureLogger.security, level: .info)
                
                self.peerIDToFingerprint.removeValue(forKey: existingPeerID)
                
                // Transfer nickname if known
                if let nickname = self.peerNicknames[existingPeerID] {
                    self.peerNicknames[newPeerID] = nickname
                    self.peerNicknames.removeValue(forKey: existingPeerID)
                }
                
                // Update active peers set
                if self.activePeers.contains(existingPeerID) {
                    self.activePeers.remove(existingPeerID)
                    // Don't pre-insert the new peer ID - let the announce packet handle it
                    // This ensures the connect message logic works properly
                }
                
                // Transfer any connected peripherals
                if let peripheral = self.connectedPeripherals[existingPeerID] {
                    self.connectedPeripherals.removeValue(forKey: existingPeerID)
                    self.connectedPeripherals[newPeerID] = peripheral
                }
                
                // Transfer RSSI data
                if let rssi = self.peerRSSI[existingPeerID] {
                    self.peerRSSI.removeValue(forKey: existingPeerID)
                    self.peerRSSI[newPeerID] = rssi
                }
                
                // Transfer lastHeardFromPeer tracking
                if let lastHeard = self.lastHeardFromPeer[existingPeerID] {
                    self.lastHeardFromPeer.removeValue(forKey: existingPeerID)
                    self.lastHeardFromPeer[newPeerID] = lastHeard
                }
            }
            
            // Add new mapping
            self.peerIDToFingerprint[newPeerID] = fingerprint
            self.fingerprintToPeerID[fingerprint] = newPeerID
            self.peerIdentityBindings[fingerprint] = binding
            
            // Cache public keys to avoid keychain lookups
            self.peerPublicKeyCache[newPeerID] = binding.publicKey
            self.peerSigningKeyCache[newPeerID] = binding.signingPublicKey
            self.identityCacheTimestamps[newPeerID] = Date()
            
            // Also update nickname from binding
            self.peerNicknames[newPeerID] = binding.nickname
            
            // Notify about the change if it's a rotation
            if let oldID = oldPeerID {
                // Clear the old session instead of migrating it
                // This ensures both peers do a fresh handshake after ID rotation
                self.cleanupPeerCryptoState(oldID)
                self.handshakeCoordinator.resetHandshakeState(for: newPeerID)
                
                // Log the peer ID rotation
                SecureLogger.log("Cleared session for peer ID rotation: \(oldID) -> \(newPeerID), will establish fresh handshake", 
                               category: SecureLogger.handshake, level: .info)
                
                self.notifyPeerIDChange(oldPeerID: oldID, newPeerID: newPeerID, fingerprint: fingerprint)
                
                // Trigger handshake after a short delay to allow the peer to settle
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                    self?.initiateNoiseHandshake(with: newPeerID)
                }
            }
        }
    }
    
    // Get current peer ID for a fingerprint
    func getCurrentPeerID(for fingerprint: String) -> String? {
        return collectionsQueue.sync {
            fingerprintToPeerID[fingerprint]
        }
    }
    
    // Get fingerprint for a peer ID
    func getFingerprint(for peerID: String) -> String? {
        return collectionsQueue.sync {
            peerIDToFingerprint[peerID]
        }
    }
    
    // Check if a peer ID belongs to us (current or previous)
    func isPeerIDOurs(_ peerID: String) -> Bool {
        if peerID == myPeerID {
            return true
        }
        
        // Check if it's our previous ID within grace period
        if let previousID = previousPeerID,
           peerID == previousID,
           let rotationTime = rotationTimestamp,
           Date().timeIntervalSince(rotationTime) < rotationGracePeriod {
            return true
        }
        
        return false
    }
    
    // Update peer connection state
    private func updatePeerConnectionState(_ peerID: String, state: PeerConnectionState) {
        connectionStateQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            let previousState = self.peerConnectionStates[peerID]
            self.peerConnectionStates[peerID] = state
            
            SecureLogger.log("Peer \(peerID) connection state: \(previousState?.description ?? "nil") -> \(state)", 
                           category: SecureLogger.session, level: .debug)
            
            // Update activePeers based on authentication state
            self.collectionsQueue.async(flags: .barrier) {
                switch state {
                case .authenticated:
                    if !self.activePeers.contains(peerID) {
                        self.activePeers.insert(peerID)
                        SecureLogger.log("Added \(peerID) to activePeers (authenticated)", 
                                       category: SecureLogger.session, level: .info)
                    }
                case .disconnected:
                    if self.activePeers.contains(peerID) {
                        self.activePeers.remove(peerID)
                        SecureLogger.log("Removed \(peerID) from activePeers (disconnected)", 
                                       category: SecureLogger.session, level: .info)
                    }
                default:
                    break
                }
                
                // Always notify peer list update when connection state changes
                DispatchQueue.main.async {
                    self.notifyPeerListUpdate(immediate: true)
                }
            }
        }
    }
    
    // Get peer connection state
    func getPeerConnectionState(_ peerID: String) -> PeerConnectionState {
        return connectionStateQueue.sync {
            peerConnectionStates[peerID] ?? .disconnected
        }
    }
    
    // MARK: - Peer ID Rotation
    
    private func generateNewPeerID() -> String {
        // Generate 8 random bytes (64 bits) for strong collision resistance
        var randomBytes = [UInt8](repeating: 0, count: 8)
        let result = SecRandomCopyBytes(kSecRandomDefault, 8, &randomBytes)
        
        // If SecRandomCopyBytes fails, use alternative randomization
        if result != errSecSuccess {
            for i in 0..<8 {
                randomBytes[i] = UInt8.random(in: 0...255)
            }
        }
        
        // Add timestamp entropy to ensure uniqueness
        // Use lower 32 bits of timestamp in milliseconds to avoid overflow
        let timestampMs = UInt64(Date().timeIntervalSince1970 * 1000)
        let timestamp = UInt32(timestampMs & 0xFFFFFFFF)
        randomBytes[4] = UInt8((timestamp >> 24) & 0xFF)
        randomBytes[5] = UInt8((timestamp >> 16) & 0xFF)
        randomBytes[6] = UInt8((timestamp >> 8) & 0xFF)
        randomBytes[7] = UInt8(timestamp & 0xFF)
        
        return randomBytes.map { String(format: "%02x", $0) }.joined()
    }
    
    func rotatePeerID() {
        guard !rotationLocked else {
            // Schedule rotation for later
            scheduleRotation(delay: 30.0)
            return
        }
        
        collectionsQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            // Save current peer ID as previous
            let oldID = self.myPeerID
            self.previousPeerID = oldID
            self.rotationTimestamp = Date()
            
            // Generate new peer ID
            self.myPeerID = self.generateNewPeerID()
            
            SecureLogger.log("Peer ID rotated from \(oldID) to \(self.myPeerID)", category: SecureLogger.security, level: .info)
            
            // Update advertising with new peer ID
            DispatchQueue.main.async { [weak self] in
                self?.updateAdvertisement()
            }
            
            // Send identity announcement with new peer ID
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                self?.sendNoiseIdentityAnnounce()
            }
            
            // Schedule next rotation
            self.scheduleNextRotation()
        }
    }
    
    private func scheduleRotation(delay: TimeInterval) {
        DispatchQueue.main.async { [weak self] in
            self?.rotationTimer?.invalidate()
            self?.rotationTimer = Timer.scheduledTimer(withTimeInterval: delay, repeats: false) { _ in
                self?.rotatePeerID()
            }
        }
    }
    
    private func scheduleNextRotation() {
        // Base interval: 1-6 hours
        let baseInterval = TimeInterval.random(in: 3600...21600)
        
        // Add jitter: ±30 minutes
        let jitter = TimeInterval.random(in: -1800...1800)
        
        // Additional random delay to prevent synchronization
        let networkDelay = TimeInterval.random(in: 0...300) // 0-5 minutes
        
        let nextRotation = baseInterval + jitter + networkDelay
        
        scheduleRotation(delay: nextRotation)
    }
    
    private func updateAdvertisement() {
        guard isAdvertising else { return }
        
        peripheralManager?.stopAdvertising()
        
        // Update advertisement data with new peer ID
        advertisementData = [
            CBAdvertisementDataServiceUUIDsKey: [BluetoothMeshService.serviceUUID],
            CBAdvertisementDataLocalNameKey: myPeerID
        ]
        
        peripheralManager?.startAdvertising(advertisementData)
    }
    
    func lockRotation() {
        rotationLocked = true
    }
    
    func unlockRotation() {
        rotationLocked = false
    }
    
    override init() {
        // Generate ephemeral peer ID for each session to prevent tracking
        self.myPeerID = ""
        super.init()
        self.myPeerID = generateNewPeerID()
        
        centralManager = CBCentralManager(delegate: self, queue: nil)
        peripheralManager = CBPeripheralManager(delegate: self, queue: nil)
        
        // Start bloom filter reset timer (reset every 5 minutes)
        bloomFilterResetTimer = Timer.scheduledTimer(withTimeInterval: 300.0, repeats: true) { [weak self] _ in
            self?.messageQueue.async(flags: .barrier) {
                guard let self = self else { return }
                
                // Adapt Bloom filter size based on network size
                let networkSize = self.estimatedNetworkSize
                self.messageBloomFilter = OptimizedBloomFilter.adaptive(for: networkSize)
                
                // Clear other duplicate detection sets
                self.processedMessages.removeAll()
                
            }
        }
        
        // Start stale peer cleanup timer (every 30 seconds)
        cleanupTimer = Timer.scheduledTimer(withTimeInterval: 60.0, repeats: true) { [weak self] _ in
            self?.cleanupStalePeers()
        }
        
        // Start ACK timeout checking timer (every 2 seconds for timely retries)
        Timer.scheduledTimer(withTimeInterval: 2.0, repeats: true) { [weak self] _ in
            self?.checkAckTimeouts()
        }
        
        // Start peer availability checking timer (every 5 seconds)
        availabilityCheckTimer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: true) { [weak self] _ in
            self?.checkPeerAvailability()
        }
        
        // Start write queue cleanup timer (every 30 seconds)
        writeQueueTimer = Timer.scheduledTimer(withTimeInterval: 30.0, repeats: true) { [weak self] _ in
            self?.cleanExpiredWriteQueues()
        }
        
        // Start identity cache cleanup timer (every hour)
        Timer.scheduledTimer(withTimeInterval: 3600.0, repeats: true) { [weak self] _ in
            self?.cleanExpiredIdentityCache()
        }
        
        // Log handshake states periodically for debugging and clean up stale states
        #if DEBUG
        Timer.scheduledTimer(withTimeInterval: 30.0, repeats: true) { [weak self] _ in
            guard let self = self else { return }
            
            // Clean up stale handshakes
            let stalePeerIDs = self.handshakeCoordinator.cleanupStaleHandshakes()
            if !stalePeerIDs.isEmpty {
                for peerID in stalePeerIDs {
                    // Also remove from noise service
                    self.cleanupPeerCryptoState(peerID)
                    SecureLogger.log("Cleaned up stale handshake for \(peerID)", category: SecureLogger.handshake, level: .info)
                }
            }
            
            self.handshakeCoordinator.logHandshakeStates()
        }
        #endif
        
        // Schedule first peer ID rotation
        scheduleNextRotation()
        
        // Setup noise callbacks
        noiseService.onPeerAuthenticated = { [weak self] peerID, fingerprint in
            // Get peer's public key data from noise service
            if let publicKeyData = self?.noiseService.getPeerPublicKeyData(peerID) {
                // Register with ChatViewModel for verification tracking
                DispatchQueue.main.async {
                    (self?.delegate as? ChatViewModel)?.registerPeerPublicKey(peerID: peerID, publicKeyData: publicKeyData)
                    
                    // Force UI to update encryption status for this specific peer
                    (self?.delegate as? ChatViewModel)?.updateEncryptionStatusForPeer(peerID)
                }
            }
            
            // Send regular announce packet when authenticated to trigger connect message
            // This covers the case where we're the responder in the handshake
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) { [weak self] in
                self?.sendAnnouncementToPeer(peerID)
            }
        }
        
        // Register for app termination notifications
        #if os(macOS)
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(appWillTerminate),
            name: NSApplication.willTerminateNotification,
            object: nil
        )
        #else
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(appWillTerminate),
            name: UIApplication.willTerminateNotification,
            object: nil
        )
        #endif
    }
    
    deinit {
        cleanup()
        scanDutyCycleTimer?.invalidate()
        batteryMonitorTimer?.invalidate()
        coverTrafficTimer?.invalidate()
        bloomFilterResetTimer?.invalidate()
        aggregationTimer?.invalidate()
        cleanupTimer?.invalidate()
        rotationTimer?.invalidate()
    }
    
    @objc private func appWillTerminate() {
        cleanup()
    }
    
    private func cleanup() {
        // Send leave announcement before disconnecting
        sendLeaveAnnouncement()
        
        // Give the leave message time to send
        Thread.sleep(forTimeInterval: 0.2)
        
        // First, disconnect all peripherals which will trigger disconnect delegates
        for (_, peripheral) in connectedPeripherals {
            centralManager?.cancelPeripheralConnection(peripheral)
        }
        
        // Stop advertising
        if peripheralManager?.isAdvertising == true {
            peripheralManager?.stopAdvertising()
        }
        
        // Stop scanning
        centralManager?.stopScan()
        
        // Remove all services - this will disconnect any connected centrals
        if peripheralManager?.state == .poweredOn {
            peripheralManager?.removeAllServices()
        }
        
        // Clear all tracking
        connectedPeripherals.removeAll()
        subscribedCentrals.removeAll()
        collectionsQueue.sync(flags: .barrier) {
            activePeers.removeAll()
        }
        announcedPeers.removeAll()
        // For normal disconnect, respect the timing
        networkBecameEmptyTime = Date()
        
        // Clear announcement tracking
        announcedToPeers.removeAll()
        
        // Clear last seen timestamps
        peerLastSeenTimestamps.removeAll()
        
        // Clear all encryption queues
        encryptionQueuesLock.lock()
        peerEncryptionQueues.removeAll()
        encryptionQueuesLock.unlock()
        
        // Clear peer tracking
        lastHeardFromPeer.removeAll()
    }
    
    func startServices() {
        // Starting services
        // Start both central and peripheral services
        if centralManager?.state == .poweredOn {
            startScanning()
        }
        if peripheralManager?.state == .poweredOn {
            setupPeripheral()
            startAdvertising()
        }
        
        // Send initial announces after services are ready
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) { [weak self] in
            self?.sendBroadcastAnnounce()
        }
        
        // Setup battery optimizer
        setupBatteryOptimizer()
        
        // Start cover traffic for privacy
        startCoverTraffic()
    }
    
    func sendBroadcastAnnounce() {
        guard let vm = delegate as? ChatViewModel else { return }
        
        
        let announcePacket = BitchatPacket(
            type: MessageType.announce.rawValue,
            ttl: 3,  // Increase TTL so announce reaches all peers
            senderID: myPeerID,
            payload: Data(vm.nickname.utf8)
        )
        
        
        // Initial send with random delay
        let initialDelay = self.randomDelay()
        DispatchQueue.main.asyncAfter(deadline: .now() + initialDelay) { [weak self] in
            self?.broadcastPacket(announcePacket)
            
            // Also send Noise identity announcement
            self?.sendNoiseIdentityAnnounce()
        }
        
        // Send multiple times for reliability with jittered delays
        for baseDelay in [0.2, 0.5, 1.0] {
            let jitteredDelay = baseDelay + self.randomDelay()
            DispatchQueue.main.asyncAfter(deadline: .now() + jitteredDelay) { [weak self] in
                guard let self = self else { return }
                self.broadcastPacket(announcePacket)
            }
        }
    }
    
    func startAdvertising() {
        guard peripheralManager?.state == .poweredOn else { 
            return 
        }
        
        // Use generic advertising to avoid identification
        // No identifying prefixes or app names for activist safety
        
        // Only use allowed advertisement keys
        advertisementData = [
            CBAdvertisementDataServiceUUIDsKey: [BluetoothMeshService.serviceUUID],
            // Use only peer ID without any identifying prefix
            CBAdvertisementDataLocalNameKey: myPeerID
        ]
        
        isAdvertising = true
        peripheralManager?.startAdvertising(advertisementData)
    }
    
    func startScanning() {
        guard centralManager?.state == .poweredOn else { 
            return 
        }
        
        // Enable duplicate detection for RSSI tracking
        let scanOptions: [String: Any] = [
            CBCentralManagerScanOptionAllowDuplicatesKey: true
        ]
        
        centralManager?.scanForPeripherals(
            withServices: [BluetoothMeshService.serviceUUID],
            options: scanOptions
        )
        
        // Update scan parameters based on battery before starting
        updateScanParametersForBattery()
        
        // Implement scan duty cycling for battery efficiency
        scheduleScanDutyCycle()
    }
    
    private func scheduleScanDutyCycle() {
        guard scanDutyCycleTimer == nil else { return }
        
        // Start with active scanning
        isActivelyScanning = true
        
        scanDutyCycleTimer = Timer.scheduledTimer(withTimeInterval: activeScanDuration, repeats: true) { [weak self] _ in
            guard let self = self else { return }
            
            if self.isActivelyScanning {
                // Pause scanning to save battery
                self.centralManager?.stopScan()
                self.isActivelyScanning = false
                
                // Schedule resume
                DispatchQueue.main.asyncAfter(deadline: .now() + self.scanPauseDuration) { [weak self] in
                    guard let self = self else { return }
                    if self.centralManager?.state == .poweredOn {
                        self.centralManager?.scanForPeripherals(
                            withServices: [BluetoothMeshService.serviceUUID],
                            options: [CBCentralManagerScanOptionAllowDuplicatesKey: true]
                        )
                        self.isActivelyScanning = true
                    }
                }
            }
        }
    }
    
    private func setupPeripheral() {
        let characteristic = CBMutableCharacteristic(
            type: BluetoothMeshService.characteristicUUID,
            properties: [.read, .write, .writeWithoutResponse, .notify],
            value: nil,
            permissions: [.readable, .writeable]
        )
        
        let service = CBMutableService(type: BluetoothMeshService.serviceUUID, primary: true)
        service.characteristics = [characteristic]
        
        peripheralManager?.add(service)
        self.characteristic = characteristic
    }
    
    func sendMessage(_ content: String, mentions: [String] = [], to recipientID: String? = nil, messageID: String? = nil, timestamp: Date? = nil) {
        // Defensive check for empty content
        guard !content.isEmpty else { return }
        messageQueue.async { [weak self] in
            guard let self = self else { return }
            
            let nickname = self.delegate as? ChatViewModel
            let senderNick = nickname?.nickname ?? self.myPeerID
            
            let message = BitchatMessage(
                id: messageID,
                sender: senderNick,
                content: content,
                timestamp: timestamp ?? Date(),
                isRelay: false,
                originalSender: nil,
                isPrivate: false,
                recipientNickname: nil,
                senderPeerID: self.myPeerID,
                mentions: mentions.isEmpty ? nil : mentions
            )
            
            if let messageData = message.toBinaryPayload() {
                
                
                // Use unified message type with broadcast recipient
                let packet = BitchatPacket(
                    type: MessageType.message.rawValue,
                    senderID: Data(hexString: self.myPeerID) ?? Data(),
                    recipientID: SpecialRecipients.broadcast,  // Special broadcast ID
                    timestamp: UInt64(Date().timeIntervalSince1970 * 1000), // milliseconds
                    payload: messageData,
                    signature: nil,
                    ttl: self.adaptiveTTL
                )
                
                // Track this message to prevent duplicate sends
                let msgID = "\(packet.timestamp)-\(self.myPeerID)-\(packet.payload.prefix(32).hashValue)"
                
                let shouldSend = !self.recentlySentMessages.contains(msgID)
                if shouldSend {
                    self.recentlySentMessages.insert(msgID)
                }
                
                if shouldSend {
                    // Clean up old entries after 10 seconds
                    self.messageQueue.asyncAfter(deadline: .now() + 10.0) { [weak self] in
                        guard let self = self else { return }
                        self.recentlySentMessages.remove(msgID)
                    }
                    
                    // Add random delay before initial send
                    let initialDelay = self.randomDelay()
                    DispatchQueue.main.asyncAfter(deadline: .now() + initialDelay) { [weak self] in
                        self?.broadcastPacket(packet)
                    }
                    
                    // Single retry for reliability
                    let retryDelay = 0.3 + self.randomDelay()
                    DispatchQueue.main.asyncAfter(deadline: .now() + retryDelay) { [weak self] in
                        self?.broadcastPacket(packet)
                        // Re-sending message
                    }
                }
            }
        }
    }
    
    
    func sendPrivateMessage(_ content: String, to recipientPeerID: String, recipientNickname: String, messageID: String? = nil) {
        // Defensive checks
        guard !content.isEmpty, !recipientPeerID.isEmpty, !recipientNickname.isEmpty else { 
            return 
        }
        
        let msgID = messageID ?? UUID().uuidString
        
        messageQueue.async { [weak self] in
            guard let self = self else { return }
            
            // Check if this is an old peer ID that has rotated
            var targetPeerID = recipientPeerID
            
            // If we have a fingerprint for this peer ID, check if there's a newer peer ID
            if let fingerprint = self.collectionsQueue.sync(execute: { self.peerIDToFingerprint[recipientPeerID] }),
               let currentPeerID = self.collectionsQueue.sync(execute: { self.fingerprintToPeerID[fingerprint] }),
               currentPeerID != recipientPeerID {
                // Use the current peer ID instead
                targetPeerID = currentPeerID
            }
            
            // Always use Noise encryption
            self.sendPrivateMessageViaNoise(content, to: targetPeerID, recipientNickname: recipientNickname, messageID: msgID)
        }
    }
    
    // Public method to get current peer ID for a fingerprint
    func getCurrentPeerIDForFingerprint(_ fingerprint: String) -> String? {
        return collectionsQueue.sync {
            return fingerprintToPeerID[fingerprint]
        }
    }
    
    // Public method to get all current peer IDs for known fingerprints
    func getCurrentPeerIDs() -> [String: String] {
        return collectionsQueue.sync {
            return fingerprintToPeerID
        }
    }
    
    // Notify delegate when peer ID changes
    private func notifyPeerIDChange(oldPeerID: String, newPeerID: String, fingerprint: String) {
        DispatchQueue.main.async { [weak self] in
            // Remove old peer ID from active peers and announcedPeers
            self?.collectionsQueue.sync(flags: .barrier) {
                _ = self?.activePeers.remove(oldPeerID)
                // Don't pre-insert the new peer ID - let the announce packet handle it
                // This ensures the connect message logic works properly
            }
            
            // Also remove from announcedPeers so the new ID can trigger a connect message
            self?.announcedPeers.remove(oldPeerID)
            
            // Update peer list
            self?.notifyPeerListUpdate(immediate: true)
            
            // Don't send disconnect/connect messages for peer ID rotation
            // The peer didn't actually disconnect, they just rotated their ID
            // This prevents confusing messages like "3a7e1c2c0d8943b9 disconnected"
            
            // Instead, notify the delegate about the peer ID change if needed
            // (Could add a new delegate method for this in the future)
        }
    }
    
    
    func sendDeliveryAck(_ ack: DeliveryAck, to recipientID: String) {
        // Use per-peer encryption queue to prevent nonce desynchronization
        let encryptionQueue = getEncryptionQueue(for: recipientID)
        
        encryptionQueue.async { [weak self] in
            guard let self = self else { return }
            
            // Encode the ACK
            let ackData = ack.toBinaryData()
            
            // Check if we have a Noise session with this peer
            // Use noiseService directly
            if self.noiseService.hasEstablishedSession(with: recipientID) {
                // Use Noise encryption - encrypt only the ACK payload directly
                do {
                    // Create a special payload that indicates this is a delivery ACK
                    // Format: [1 byte type marker] + [ACK JSON data]
                    var ackPayload = Data()
                    ackPayload.append(MessageType.deliveryAck.rawValue) // Type marker
                    ackPayload.append(ackData) // ACK JSON
                    
                    // Encrypt only the payload (not a full packet)
                    let encryptedPayload = try noiseService.encrypt(ackPayload, for: recipientID)
                    
                    // Create outer Noise packet with the encrypted payload
                    let outerPacket = BitchatPacket(
                        type: MessageType.noiseEncrypted.rawValue,
                        senderID: Data(hexString: self.myPeerID) ?? Data(),
                        recipientID: Data(hexString: recipientID) ?? Data(),
                        timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                        payload: encryptedPayload,
                        signature: nil,
                        ttl: 3
                    )
                    
                    self.broadcastPacket(outerPacket)
                } catch {
                    SecureLogger.logError(error, context: "Failed to encrypt delivery ACK via Noise for \(recipientID)", category: SecureLogger.encryption)
                }
            } else {
                // Fall back to legacy encryption
                let encryptedPayload: Data
                do {
                    encryptedPayload = try self.noiseService.encrypt(ackData, for: recipientID)
                } catch {
                    SecureLogger.logError(error, context: "Failed to encrypt delivery ACK for \(recipientID)", category: SecureLogger.encryption)
                    return
                }
                
                // Create ACK packet with direct routing to original sender
                let packet = BitchatPacket(
                    type: MessageType.deliveryAck.rawValue,
                    senderID: Data(hexString: self.myPeerID) ?? Data(),
                    recipientID: Data(hexString: recipientID) ?? Data(),
                    timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                    payload: encryptedPayload,
                    signature: nil,  // ACKs don't need signatures
                    ttl: 3  // Limited TTL for ACKs
                )
                
                // Send immediately without delay (ACKs should be fast)
                self.broadcastPacket(packet)
            }
        }
    }
    
    private func getEncryptionQueue(for peerID: String) -> DispatchQueue {
        encryptionQueuesLock.lock()
        defer { encryptionQueuesLock.unlock() }
        
        if let queue = peerEncryptionQueues[peerID] {
            return queue
        }
        
        let queue = DispatchQueue(label: "bitchat.encryption.\(peerID)", qos: .userInitiated)
        peerEncryptionQueues[peerID] = queue
        return queue
    }
    
    private func removeEncryptionQueue(for peerID: String) {
        encryptionQueuesLock.lock()
        defer { encryptionQueuesLock.unlock() }
        
        peerEncryptionQueues.removeValue(forKey: peerID)
    }
    
    // Centralized cleanup for peer crypto state
    private func cleanupPeerCryptoState(_ peerID: String) {
        noiseService.removePeer(peerID)
        handshakeCoordinator.resetHandshakeState(for: peerID)
        removeEncryptionQueue(for: peerID)
    }
    
    func sendReadReceipt(_ receipt: ReadReceipt, to recipientID: String) {
        // Use per-peer encryption queue to prevent nonce desynchronization
        let encryptionQueue = getEncryptionQueue(for: recipientID)
        
        encryptionQueue.async { [weak self] in
            guard let self = self else { return }
            
            // Encode the receipt
            let receiptData = receipt.toBinaryData()
            
            // Check if we have a Noise session with this peer
            // Use noiseService directly
            if self.noiseService.hasEstablishedSession(with: recipientID) {
                // Use Noise encryption - send as Noise encrypted message
                do {
                    // Create inner read receipt packet
                    let innerPacket = BitchatPacket(
                        type: MessageType.readReceipt.rawValue,
                        senderID: Data(hexString: self.myPeerID) ?? Data(),
                        recipientID: Data(hexString: recipientID) ?? Data(),
                        timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                        payload: receiptData,
                        signature: nil,
                        ttl: 3
                    )
                    
                    // Encrypt the entire inner packet
                    if let innerData = innerPacket.toBinaryData() {
                        let encryptedInnerData = try noiseService.encrypt(innerData, for: recipientID)
                        
                        // Create outer Noise packet
                        let outerPacket = BitchatPacket(
                            type: MessageType.noiseEncrypted.rawValue,
                            senderID: Data(hexString: self.myPeerID) ?? Data(),
                            recipientID: Data(hexString: recipientID) ?? Data(),
                            timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                            payload: encryptedInnerData,
                            signature: nil,
                            ttl: 3
                        )
                        
                        SecureLogger.log("Sending encrypted read receipt for message \(receipt.originalMessageID) to \(recipientID)", category: SecureLogger.noise, level: .info)
                        self.broadcastPacket(outerPacket)
                    }
                } catch {
                    SecureLogger.logError(error, context: "Failed to encrypt read receipt via Noise for \(recipientID)", category: SecureLogger.encryption)
                }
            } else {
                // No session - initiate handshake and queue the read receipt
                SecureLogger.log("No Noise session with \(recipientID) for read receipt, initiating handshake", category: SecureLogger.noise, level: .info)
                
                // Initiate handshake regardless of our role if we need to send data
                self.initiateNoiseHandshake(with: recipientID)
                
                // Queue the read receipt as a pending message
                // Create a synthetic message ID for the read receipt
                let readReceiptMessageID = "READ_RECEIPT_\(receipt.originalMessageID)"
                
                collectionsQueue.sync(flags: .barrier) {
                    if self.pendingPrivateMessages[recipientID] == nil {
                        self.pendingPrivateMessages[recipientID] = []
                    }
                    
                    // Store the read receipt data as a pending "message"
                    self.pendingPrivateMessages[recipientID]?.append((
                        content: "READ_RECEIPT:\(receipt.originalMessageID)",
                        recipientNickname: receipt.readerNickname,
                        messageID: readReceiptMessageID
                    ))
                    
                    let count = self.pendingPrivateMessages[recipientID]?.count ?? 0
                    SecureLogger.log("Queued read receipt for \(recipientID), pending messages: \(count)", category: SecureLogger.noise, level: .info)
                }
            }
        }
    }
    
    
    
    
    
    private func sendAnnouncementToPeer(_ peerID: String) {
        guard let vm = delegate as? ChatViewModel else { return }
        
        
        // Always send announce, don't check if already announced
        // This ensures peers get our nickname even if they reconnect
        
        let packet = BitchatPacket(
            type: MessageType.announce.rawValue,
            ttl: 3,  // Allow relay for better reach
            senderID: myPeerID,
            payload: Data(vm.nickname.utf8)
        )
        
        if let data = packet.toBinaryData() {
            // Try both broadcast and targeted send
            broadcastPacket(packet)
            
            // Also try targeted send if we have the peripheral
            if let peripheral = connectedPeripherals[peerID],
               peripheral.state == .connected,
               let characteristic = peripheral.services?.first(where: { $0.uuid == BluetoothMeshService.serviceUUID })?.characteristics?.first(where: { $0.uuid == BluetoothMeshService.characteristicUUID }) {
                writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: peerID)
            } else {
            }
        } else {
        }
        
        announcedToPeers.insert(peerID)
    }
    
    private func sendLeaveAnnouncement() {
        guard let vm = delegate as? ChatViewModel else { return }
        
        let packet = BitchatPacket(
            type: MessageType.leave.rawValue,
            ttl: 1,  // Don't relay leave messages
            senderID: myPeerID,
            payload: Data(vm.nickname.utf8)
        )
        
        broadcastPacket(packet)
    }
    
    
    func getPeerNicknames() -> [String: String] {
        return collectionsQueue.sync {
            return peerNicknames
        }
    }
    
    func getPeerRSSI() -> [String: NSNumber] {
        // Return actual RSSI values only - no fake defaults
        // UI should handle missing values gracefully
        return peerRSSI
    }
    
    // Emergency disconnect for panic situations
    func emergencyDisconnectAll() {
        SecureLogger.log("Emergency disconnect triggered", category: SecureLogger.security, level: .warning)
        
        // Stop advertising immediately
        if peripheralManager?.isAdvertising == true {
            peripheralManager?.stopAdvertising()
        }
        
        // Stop scanning
        centralManager?.stopScan()
        scanDutyCycleTimer?.invalidate()
        scanDutyCycleTimer = nil
        
        // Disconnect all peripherals
        for (peerID, peripheral) in connectedPeripherals {
            SecureLogger.log("Emergency disconnect peer: \(peerID)", category: SecureLogger.session, level: .warning)
            centralManager?.cancelPeripheralConnection(peripheral)
        }
        
        // Clear all peer data
        connectedPeripherals.removeAll()
        peripheralCharacteristics.removeAll()
        discoveredPeripherals.removeAll()
        subscribedCentrals.removeAll()
        peerNicknames.removeAll()
        activePeers.removeAll()
        peerRSSI.removeAll()
        peripheralRSSI.removeAll()
        announcedToPeers.removeAll()
        announcedPeers.removeAll()
        // For emergency/panic, reset immediately
        hasNotifiedNetworkAvailable = false
        networkBecameEmptyTime = nil
        lastNetworkNotificationTime = nil
        processedMessages.removeAll()
        incomingFragments.removeAll()
        
        // Clear all encryption queues
        encryptionQueuesLock.lock()
        peerEncryptionQueues.removeAll()
        encryptionQueuesLock.unlock()
        fragmentMetadata.removeAll()
        
        // Clear peer tracking
        lastHeardFromPeer.removeAll()
        
        // Clear persistent identity
        noiseService.clearPersistentIdentity()
        
        // Clear all handshake coordinator states
        handshakeCoordinator.clearAllHandshakeStates()
        
        // Clear handshake attempt times
        handshakeAttemptTimes.removeAll()
        
        // Notify UI that all peers are disconnected
        DispatchQueue.main.async { [weak self] in
            self?.delegate?.didUpdatePeerList([])
        }
    }
    
    private func getAllConnectedPeerIDs() -> [String] {
        // Return all valid active peers
        let peersCopy = collectionsQueue.sync {
            return activePeers
        }
        
        
        let validPeers = peersCopy.filter { peerID in
            // Ensure peerID is valid and not self
            let isEmpty = peerID.isEmpty
            let isUnknown = peerID == "unknown"
            let isSelf = peerID == self.myPeerID
            
            return !isEmpty && !isUnknown && !isSelf
        }
        
        let result = Array(validPeers).sorted()
        return result
    }
    
    // Debounced peer list update notification
    private func notifyPeerListUpdate(immediate: Bool = false) {
        if immediate {
            // For initial connections, update immediately
            let connectedPeerIDs = self.getAllConnectedPeerIDs()
            
            DispatchQueue.main.async {
                self.delegate?.didUpdatePeerList(connectedPeerIDs)
            }
        } else {
            // Must schedule timer on main thread
            DispatchQueue.main.async { [weak self] in
                guard let self = self else { return }
                
                // Cancel any pending update
                self.peerListUpdateTimer?.invalidate()
                
                // Schedule a new update after debounce interval
                self.peerListUpdateTimer = Timer.scheduledTimer(withTimeInterval: self.peerListUpdateDebounceInterval, repeats: false) { [weak self] _ in
                    guard let self = self else { return }
                    
                    let connectedPeerIDs = self.getAllConnectedPeerIDs()
                    
                    self.delegate?.didUpdatePeerList(connectedPeerIDs)
                }
            }
        }
    }
    
    // Clean up stale peers that haven't been seen in a while
    private func cleanupStalePeers() {
        let staleThreshold: TimeInterval = 180.0 // 3 minutes - increased for better stability
        let now = Date()
        
        let peersToRemove = collectionsQueue.sync(flags: .barrier) {
            let toRemove = activePeers.filter { peerID in
                if let lastSeen = peerLastSeenTimestamps.get(peerID) {
                    return now.timeIntervalSince(lastSeen) > staleThreshold
                }
                return false // Keep peers we haven't tracked yet
            }
            
            var actuallyRemoved: [String] = []
            
            for peerID in toRemove {
                // Check if this peer has an active peripheral connection
                if let peripheral = connectedPeripherals[peerID], peripheral.state == .connected {
                    // Skipping removal - still has active connection
                    // Update last seen time to prevent immediate re-removal
                    peerLastSeenTimestamps.set(peerID, value: Date())
                    continue
                }
                
                let nickname = peerNicknames[peerID] ?? "unknown"
                activePeers.remove(peerID)
                peerLastSeenTimestamps.remove(peerID)
                SecureLogger.log("📴 Removed stale peer from network: \(peerID) (\(nickname))", category: SecureLogger.session, level: .info)
                
                // Clean up all associated data
                connectedPeripherals.removeValue(forKey: peerID)
                peerRSSI.removeValue(forKey: peerID)
                announcedPeers.remove(peerID)
                announcedToPeers.remove(peerID)
                peerNicknames.removeValue(forKey: peerID)
                lastHeardFromPeer.removeValue(forKey: peerID)
                
                actuallyRemoved.append(peerID)
                // Removed stale peer
            }
            return actuallyRemoved
        }
        
        if !peersToRemove.isEmpty {
            notifyPeerListUpdate()
            
            // Mark when network became empty, but don't reset flag immediately
            let currentNetworkSize = collectionsQueue.sync { activePeers.count }
            if currentNetworkSize == 0 && networkBecameEmptyTime == nil {
                networkBecameEmptyTime = Date()
            }
        }
        
        // Check if we should reset the notification flag
        if let emptyTime = networkBecameEmptyTime {
            let currentNetworkSize = collectionsQueue.sync { activePeers.count }
            if currentNetworkSize == 0 {
                // Network is still empty, check if enough time has passed
                let timeSinceEmpty = Date().timeIntervalSince(emptyTime)
                if timeSinceEmpty >= networkEmptyResetDelay {
                    // Reset the flag after network has been empty for the delay period
                    hasNotifiedNetworkAvailable = false
                    // Keep the empty time set so we don't immediately notify again
                }
            } else {
                // Network is no longer empty, clear the empty time
                networkBecameEmptyTime = nil
            }
        }
    }
    
    // MARK: - Store-and-Forward Methods
    
    private func cacheMessage(_ packet: BitchatPacket, messageID: String) {
        messageQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            // Don't cache certain message types
            guard packet.type != MessageType.announce.rawValue,
                  packet.type != MessageType.leave.rawValue,
                  packet.type != MessageType.fragmentStart.rawValue,
                  packet.type != MessageType.fragmentContinue.rawValue,
                  packet.type != MessageType.fragmentEnd.rawValue else {
                return
            }
            
            // Don't cache broadcast messages
            if let recipientID = packet.recipientID,
               recipientID == SpecialRecipients.broadcast {
                return  // Never cache broadcast messages
            }
            
            // Check if this is a private message for a favorite
            var isForFavorite = false
            if packet.type == MessageType.message.rawValue,
               let recipientID = packet.recipientID {
                let recipientPeerID = recipientID.hexEncodedString()
                // Check if recipient is a favorite via their public key fingerprint
                if let fingerprint = self.noiseService.getPeerFingerprint(recipientPeerID) {
                    isForFavorite = self.delegate?.isFavorite(fingerprint: fingerprint) ?? false
                }
            }
            
            // Create stored message with original packet timestamp preserved
            let storedMessage = StoredMessage(
                packet: packet,
                timestamp: Date(timeIntervalSince1970: TimeInterval(packet.timestamp) / 1000.0), // convert from milliseconds
                messageID: messageID,
                isForFavorite: isForFavorite
            )
            
            
            if isForFavorite {
                if let recipientID = packet.recipientID {
                    let recipientPeerID = recipientID.hexEncodedString()
                    if self.favoriteMessageQueue[recipientPeerID] == nil {
                        self.favoriteMessageQueue[recipientPeerID] = []
                    }
                    self.favoriteMessageQueue[recipientPeerID]?.append(storedMessage)
                    
                    // Limit favorite queue size
                    if let count = self.favoriteMessageQueue[recipientPeerID]?.count,
                       count > self.maxCachedMessagesForFavorites {
                        self.favoriteMessageQueue[recipientPeerID]?.removeFirst()
                    }
                    
                }
            } else {
                // Clean up old messages first (only for regular cache)
                self.cleanupMessageCache()
                
                // Add to regular cache
                self.messageCache.append(storedMessage)
                
                // Limit cache size
                if self.messageCache.count > self.maxCachedMessages {
                    self.messageCache.removeFirst()
                }
                
            }
        }
    }
    
    private func cleanupMessageCache() {
        let cutoffTime = Date().addingTimeInterval(-messageCacheTimeout)
        // Only remove non-favorite messages that are older than timeout
        messageCache.removeAll { !$0.isForFavorite && $0.timestamp < cutoffTime }
        
        // Clean up delivered messages set periodically (keep recent 1000 entries)
        if deliveredMessages.count > 1000 {
            // Clear older entries while keeping recent ones
            deliveredMessages.removeAll()
        }
    }
    
    private func sendCachedMessages(to peerID: String) {
        messageQueue.async { [weak self] in
            guard let self = self,
                  let peripheral = self.connectedPeripherals[peerID],
                  let characteristic = self.peripheralCharacteristics[peripheral] else {
                return
            }
            
            
            // Check if we've already sent cached messages to this peer in this session
            if self.cachedMessagesSentToPeer.contains(peerID) {
                return  // Already sent cached messages to this peer in this session
            }
            
            // Mark that we're sending cached messages to this peer
            self.cachedMessagesSentToPeer.insert(peerID)
            
            // Clean up old messages first
            self.cleanupMessageCache()
            
            var messagesToSend: [StoredMessage] = []
            
            // First, check if this peer has any favorite messages waiting
            if let favoriteMessages = self.favoriteMessageQueue[peerID] {
                // Filter out already delivered messages
                let undeliveredFavoriteMessages = favoriteMessages.filter { !self.deliveredMessages.contains($0.messageID) }
                messagesToSend.append(contentsOf: undeliveredFavoriteMessages)
                // Clear the favorite queue after adding to send list
                self.favoriteMessageQueue[peerID] = nil
            }
            
            // Filter regular cached messages for this specific recipient
            let recipientMessages = self.messageCache.filter { storedMessage in
                if self.deliveredMessages.contains(storedMessage.messageID) {
                    return false
                }
                if let recipientID = storedMessage.packet.recipientID {
                    let recipientPeerID = recipientID.hexEncodedString()
                    return recipientPeerID == peerID
                }
                return false  // Don't forward broadcast messages
            }
            messagesToSend.append(contentsOf: recipientMessages)
            
            
            // Sort messages by timestamp to ensure proper ordering
            messagesToSend.sort { $0.timestamp < $1.timestamp }
            
            if !messagesToSend.isEmpty {
            }
            
            // Mark messages as delivered immediately to prevent duplicates
            let messageIDsToRemove = messagesToSend.map { $0.messageID }
            for messageID in messageIDsToRemove {
                self.deliveredMessages.insert(messageID)
            }
            
            // Send cached messages with slight delay between each
            for (index, storedMessage) in messagesToSend.enumerated() {
                let delay = Double(index) * 0.02 // 20ms between messages for faster sync
                
                DispatchQueue.main.asyncAfter(deadline: .now() + delay) { [weak self, weak peripheral] in
                    guard let peripheral = peripheral,
                          peripheral.state == .connected else {
                        return
                    }
                    
                    // Send the original packet with preserved timestamp
                    let packetToSend = storedMessage.packet
                    
                    if let data = packetToSend.toBinaryData(),
                       characteristic.properties.contains(.writeWithoutResponse) {
                        self?.writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: peerID)
                    }
                }
            }
            
            // Remove sent messages immediately
            if !messageIDsToRemove.isEmpty {
                self.messageQueue.async(flags: .barrier) {
                    // Remove only the messages we sent to this specific peer
                    self.messageCache.removeAll { message in
                        messageIDsToRemove.contains(message.messageID)
                    }
                    
                    // Also remove from favorite queue if any
                    if var favoriteQueue = self.favoriteMessageQueue[peerID] {
                        favoriteQueue.removeAll { message in
                            messageIDsToRemove.contains(message.messageID)
                        }
                        self.favoriteMessageQueue[peerID] = favoriteQueue.isEmpty ? nil : favoriteQueue
                    }
                }
            }
        }
    }
    
    private func estimateDistance(rssi: Int) -> Int {
        // Rough distance estimation based on RSSI
        // Using path loss formula: RSSI = TxPower - 10 * n * log10(distance)
        // Assuming TxPower = -59 dBm at 1m, n = 2.0 (free space)
        let txPower = -59.0
        let pathLossExponent = 2.0
        
        let ratio = (txPower - Double(rssi)) / (10.0 * pathLossExponent)
        let distance = pow(10.0, ratio)
        
        return Int(distance)
    }
    
    private func broadcastPacket(_ packet: BitchatPacket) {
        // CRITICAL CHECK: Never send unencrypted JSON
        if packet.type == MessageType.deliveryAck.rawValue {
            // Check if payload looks like JSON
            if let jsonCheck = String(data: packet.payload.prefix(1), encoding: .utf8), jsonCheck == "{" {
                // Block unencrypted JSON in delivery ACKs
                return
            }
        }
        
        
        guard let data = packet.toBinaryData() else { 
            // Failed to convert packet - add to retry queue if it's our message
            let senderID = packet.senderID.hexEncodedString()
            if senderID == self.myPeerID,
               packet.type == MessageType.message.rawValue,
               let message = BitchatMessage.fromBinaryPayload(packet.payload) {
                MessageRetryService.shared.addMessageForRetry(
                    content: message.content,
                    mentions: message.mentions,
                    isPrivate: message.isPrivate,
                    recipientPeerID: nil,
                    recipientNickname: message.recipientNickname,
                    originalMessageID: message.id,
                    originalTimestamp: message.timestamp
                )
            }
            return 
        }
        
        // Check if fragmentation is needed for large packets
        if data.count > 512 && packet.type != MessageType.fragmentStart.rawValue && 
           packet.type != MessageType.fragmentContinue.rawValue && 
           packet.type != MessageType.fragmentEnd.rawValue {
            sendFragmentedPacket(packet)
            return
        }
        
        // Send to connected peripherals (as central)
        var sentToPeripherals = 0
        for (peerID, peripheral) in connectedPeripherals {
            if let characteristic = peripheralCharacteristics[peripheral] {
                // Check if peripheral is connected before writing
                if peripheral.state == .connected {
                    // Additional safety check for characteristic properties
                    if characteristic.properties.contains(.write) || 
                       characteristic.properties.contains(.writeWithoutResponse) {
                        writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: peerID)
                        sentToPeripherals += 1
                    }
                } else {
                    if let peerID = connectedPeripherals.first(where: { $0.value == peripheral })?.key {
                        connectedPeripherals.removeValue(forKey: peerID)
                        peripheralCharacteristics.removeValue(forKey: peripheral)
                    }
                }
            }
        }
        
        // Send to subscribed centrals (as peripheral)
        var sentToCentrals = 0
        if let char = characteristic, !subscribedCentrals.isEmpty {
            // Send to all subscribed centrals
            // Note: Large packets should already be fragmented by the check at the beginning of broadcastPacket
            let success = peripheralManager?.updateValue(data, for: char, onSubscribedCentrals: nil) ?? false
            if success {
                sentToCentrals = subscribedCentrals.count
            }
        }
        
        // If no peers received the message, add to retry queue ONLY if it's our own message
        if sentToPeripherals == 0 && sentToCentrals == 0 {
            // Check if this packet originated from us
            let senderID = packet.senderID.hexEncodedString()
            if senderID == self.myPeerID {
                // This is our own message that failed to send
                if packet.type == MessageType.message.rawValue,
                   let message = BitchatMessage.fromBinaryPayload(packet.payload) {
                    MessageRetryService.shared.addMessageForRetry(
                        content: message.content,
                        mentions: message.mentions,
                        isPrivate: message.isPrivate,
                        recipientPeerID: nil,
                        recipientNickname: message.recipientNickname,
                        originalMessageID: message.id,
                        originalTimestamp: message.timestamp
                    )
                }
            }
        }
    }
    
    private func handleReceivedPacket(_ packet: BitchatPacket, from peerID: String, peripheral: CBPeripheral? = nil) {
        messageQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            // Track that we heard from this peer
            let senderID = packet.senderID.hexEncodedString()
            if !senderID.isEmpty && senderID != self.myPeerID {
                // Update peer availability
                self.updatePeerAvailability(senderID)
                
                // IMPORTANT: Update peripheral mapping for ALL message types including handshakes
                // This ensures disconnect messages work even if peer disconnects right after handshake
                if let peripheral = peripheral {
                    let peripheralID = peripheral.identifier.uuidString
                    
                    // Check if we need to update the mapping
                    if peerIDByPeripheralID[peripheralID] != senderID {
                        SecureLogger.log("Updating peripheral mapping: \(peripheralID) -> \(senderID)", 
                                       category: SecureLogger.session, level: .debug)
                        peerIDByPeripheralID[peripheralID] = senderID
                        
                        // Also ensure connectedPeripherals has the correct mapping
                        // Remove any temp ID mapping if it exists
                        let tempIDToRemove = connectedPeripherals.first(where: { $0.value == peripheral && $0.key != senderID })?.key
                        if let tempID = tempIDToRemove {
                            connectedPeripherals.removeValue(forKey: tempID)
                        }
                        connectedPeripherals[senderID] = peripheral
                    }
                }
                
                // Check if this is a reconnection after a long silence
                let wasReconnection: Bool
                if let lastHeard = self.lastHeardFromPeer[senderID] {
                    let timeSinceLastHeard = Date().timeIntervalSince(lastHeard)
                    wasReconnection = timeSinceLastHeard > 30.0
                } else {
                    // First time hearing from this peer
                    wasReconnection = true
                }
                
                self.lastHeardFromPeer[senderID] = Date()
                
                // If this is a reconnection, send our identity announcement
                if wasReconnection && packet.type != MessageType.noiseIdentityAnnounce.rawValue {
                    SecureLogger.log("Detected reconnection from \(senderID) after silence, sending identity announcement", category: SecureLogger.noise, level: .info)
                    DispatchQueue.main.async { [weak self] in
                        self?.sendNoiseIdentityAnnounce(to: senderID)
                    }
                }
            }
            
            
            // Log specific Noise packet types
            
            guard packet.ttl > 0 else { 
                return 
            }
            
            // Validate packet has payload
            guard !packet.payload.isEmpty else {
                return
            }
            
            // Update last seen timestamp for this peer
            if senderID != "unknown" && senderID != self.myPeerID {
                peerLastSeenTimestamps.set(senderID, value: Date())
            }
            
            // Replay attack protection: Check timestamp is within reasonable window (5 minutes)
            let currentTime = UInt64(Date().timeIntervalSince1970 * 1000) // milliseconds
            let timeDiff = abs(Int64(currentTime) - Int64(packet.timestamp))
            if timeDiff > 300000 { // 5 minutes in milliseconds
                SecureLogger.log("Replay attack detected - timestamp from \(senderID)", category: SecureLogger.security, level: .warning)
                SecureLogger.log("Dropped message with stale timestamp. Age: \(timeDiff/1000)s from \(senderID)", category: SecureLogger.security, level: .warning)
                return
            }
        
        // For fragments, include packet type in messageID to avoid dropping CONTINUE/END fragments
        let messageID: String
        if packet.type == MessageType.fragmentStart.rawValue || 
           packet.type == MessageType.fragmentContinue.rawValue || 
           packet.type == MessageType.fragmentEnd.rawValue {
            // Include both type and payload hash for fragments to ensure uniqueness
            messageID = "\(packet.timestamp)-\(packet.senderID.hexEncodedString())-\(packet.type)-\(packet.payload.hashValue)"
        } else {
            // Include payload hash for absolute uniqueness (handles same-second messages)
            messageID = "\(packet.timestamp)-\(packet.senderID.hexEncodedString())-\(packet.payload.prefix(64).hashValue)"
        }
        
        // Use bloom filter for efficient duplicate detection
        if messageBloomFilter.contains(messageID) {
            // Also check exact set for accuracy (bloom filter can have false positives)
            if processedMessages.contains(messageID) {
                SecureLogger.log("Dropped duplicate message: \(messageID.prefix(20))... from \(senderID)", category: SecureLogger.security, level: .debug)
                return
            } else {
                // False positive from Bloom filter
                SecureLogger.log("Bloom filter false positive for message: \(messageID.prefix(20))...", category: SecureLogger.security, level: .debug)
            }
        }
        
        messageBloomFilter.insert(messageID)
        processedMessages.insert(messageID)
        
        // Log statistics periodically
        if messageBloomFilter.insertCount % 100 == 0 {
            _ = messageBloomFilter.estimatedFalsePositiveRate
        }
        
        // Bloom filter will be reset by timer, processedMessages is now bounded
        
        // let _ = packet.senderID.hexEncodedString()
        
        
        // Note: We'll decode messages in the switch statement below, not here
        
        switch MessageType(rawValue: packet.type) {
        case .message:
            // Unified message handler for both broadcast and private messages
            // Convert binary senderID back to hex string
            let senderID = packet.senderID.hexEncodedString()
            if senderID.isEmpty {
                return
            }
            
            
            // Ignore our own messages
            if senderID == myPeerID {
                return
            }
            
            // Check if this is a broadcast or private message
            if let recipientID = packet.recipientID {
                if recipientID == SpecialRecipients.broadcast {
                    // BROADCAST MESSAGE
                    
                    // No signature verification - broadcasts are not authenticated
                    
                    // Parse broadcast message (not encrypted)
                    if let message = BitchatMessage.fromBinaryPayload(packet.payload) {
                            
                        // Store nickname mapping
                        collectionsQueue.sync(flags: .barrier) {
                            self.peerNicknames[senderID] = message.sender
                        }
                        
                        let finalContent = message.content
                        
                        let messageWithPeerID = BitchatMessage(
                            id: message.id,  // Preserve the original message ID
                            sender: message.sender,
                            content: finalContent,
                            timestamp: message.timestamp,
                            isRelay: message.isRelay,
                            originalSender: message.originalSender,
                            isPrivate: false,
                            recipientNickname: nil,
                            senderPeerID: senderID,
                            mentions: message.mentions
                        )
                        
                        // Track last message time from this peer
                        let peerID = packet.senderID.hexEncodedString()
                        self.lastMessageFromPeer.set(peerID, value: Date())
                        
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveMessage(messageWithPeerID)
                        }
                        
                    }
                    
                    // Relay broadcast messages
                    var relayPacket = packet
                    relayPacket.ttl -= 1
                    if relayPacket.ttl > 0 {
                        // Probabilistic flooding with smart relay decisions
                        let relayProb = self.adaptiveRelayProbability
                        
                        // Always relay if TTL is high (fresh messages need to spread)
                        // or if we have few peers (ensure coverage in sparse networks)
                        let shouldRelay = relayPacket.ttl >= 4 || 
                                         self.activePeers.count <= 3 ||
                                         Double.random(in: 0...1) < relayProb
                        
                        if shouldRelay {
                            SecureLogger.log("Relaying broadcast from \(senderID), TTL: \(relayPacket.ttl), peers: \(self.activePeers.count)", category: SecureLogger.noise, level: .debug)
                            // Add random delay to prevent collision storms
                            let delay = Double.random(in: minMessageDelay...maxMessageDelay)
                            DispatchQueue.main.asyncAfter(deadline: .now() + delay) { [weak self] in
                                self?.broadcastPacket(relayPacket)
                            }
                        } else {
                            SecureLogger.log("Dropped broadcast relay from \(senderID), TTL: \(relayPacket.ttl), prob: \(relayProb)", category: SecureLogger.noise, level: .debug)
                        }
                    }
                    
                } else if isPeerIDOurs(recipientID.hexEncodedString()) {
                    // PRIVATE MESSAGE FOR US
                    
                    
                    // No signature verification - broadcasts are not authenticated
                    
                    // Private messages should only come through Noise now
                    // If we're getting a private message here, it must already be decrypted from Noise
                    let decryptedPayload = packet.payload
                    
                    // Parse the message
                    if let message = BitchatMessage.fromBinaryPayload(decryptedPayload) {
                        
                        // Check if this is a dummy message for cover traffic
                        if message.content.hasPrefix(self.coverTrafficPrefix) {
                                return  // Silently discard dummy messages
                        }
                        
                        // Check if we've seen this exact message recently (within 5 seconds)
                        let messageKey = "\(senderID)-\(message.content)-\(message.timestamp)"
                        if let lastReceived = self.receivedMessageTimestamps.get(messageKey) {
                            let timeSinceLastReceived = Date().timeIntervalSince(lastReceived)
                            if timeSinceLastReceived < 5.0 {
                            }
                        }
                        self.receivedMessageTimestamps.set(messageKey, value: Date())
                        
                        // LRU cache handles cleanup automatically
                        
                        collectionsQueue.sync(flags: .barrier) {
                            if self.peerNicknames[senderID] == nil {
                                self.peerNicknames[senderID] = message.sender
                            }
                        }
                        
                        let messageWithPeerID = BitchatMessage(
                            id: message.id,  // Preserve the original message ID
                            sender: message.sender,
                            content: message.content,
                            timestamp: message.timestamp,
                            isRelay: message.isRelay,
                            originalSender: message.originalSender,
                            isPrivate: message.isPrivate,
                            recipientNickname: message.recipientNickname,
                            senderPeerID: senderID,
                            mentions: message.mentions,
                            deliveryStatus: nil  // Will be set to .delivered in ChatViewModel
                        )
                        
                        // Track last message time from this peer
                        let peerID = packet.senderID.hexEncodedString()
                        self.lastMessageFromPeer.set(peerID, value: Date())
                        
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveMessage(messageWithPeerID)
                        }
                        
                        // Generate and send ACK for private messages
                        let viewModel = self.delegate as? ChatViewModel
                        let myNickname = viewModel?.nickname ?? self.myPeerID
                        if let ack = DeliveryTracker.shared.generateAck(
                            for: messageWithPeerID,
                            myPeerID: self.myPeerID,
                            myNickname: myNickname,
                            hopCount: UInt8(self.maxTTL - packet.ttl)
                        ) {
                            self.sendDeliveryAck(ack, to: senderID)
                        }
                    } else {
                        SecureLogger.log("Failed to parse private message from binary, size: \(decryptedPayload.count)", category: SecureLogger.encryption, level: .error)
                    }
                    
                } else if packet.ttl > 0 {
                    // RELAY PRIVATE MESSAGE (not for us)
                    var relayPacket = packet
                    relayPacket.ttl -= 1
                    
                    // Check if this message is for an offline favorite and cache it
                    let recipientIDString = recipientID.hexEncodedString()
                    if let fingerprint = self.noiseService.getPeerFingerprint(recipientIDString) {
                        // Only cache if recipient is a favorite AND is currently offline
                        if (self.delegate?.isFavorite(fingerprint: fingerprint) ?? false) && !self.activePeers.contains(recipientIDString) {
                            self.cacheMessage(relayPacket, messageID: messageID)
                        }
                    }
                    
                    // Private messages are important - use higher relay probability
                    let relayProb = min(self.adaptiveRelayProbability + 0.15, 1.0)  // Boost by 15%
                    
                    // Always relay if TTL is high or we have few peers
                    let shouldRelay = relayPacket.ttl >= 4 || 
                                     self.activePeers.count <= 3 ||
                                     Double.random(in: 0...1) < relayProb
                    
                    if shouldRelay {
                        // Add random delay to prevent collision storms
                        let delay = Double.random(in: minMessageDelay...maxMessageDelay)
                        DispatchQueue.main.asyncAfter(deadline: .now() + delay) { [weak self] in
                            self?.broadcastPacket(relayPacket)
                        }
                    }
                } else {
                    // Message has recipient ID but not for us and TTL is 0
                    // Message not for us - will be relayed if TTL > 0
                }
            } else {
                // No recipient ID - this shouldn't happen for messages
                SecureLogger.log("Message packet with no recipient ID from \(senderID)", category: SecureLogger.security, level: .warning)
            }
            
        // Note: 0x02 was legacy keyExchange - removed
            
        case .announce:
            if let nickname = String(data: packet.payload, encoding: .utf8) {
                let senderID = packet.senderID.hexEncodedString()
                
                // Ignore if it's from ourselves (including previous peer IDs)
                if isPeerIDOurs(senderID) {
                    return
                }
                
                // Check if we've already announced this peer
                let isFirstAnnounce = !announcedPeers.contains(senderID)
                
                // Clean up stale peer IDs with the same nickname
                collectionsQueue.sync(flags: .barrier) {
                    var stalePeerIDs: [String] = []
                    for (existingPeerID, existingNickname) in self.peerNicknames {
                        if existingNickname == nickname && existingPeerID != senderID {
                            // Check if this peer was seen very recently (within 10 seconds)
                            let wasRecentlySeen = self.peerLastSeenTimestamps.get(existingPeerID).map { Date().timeIntervalSince($0) < 10.0 } ?? false
                            if !wasRecentlySeen {
                                // Found a stale peer ID with the same nickname
                                stalePeerIDs.append(existingPeerID)
                                // Found stale peer ID
                            } else {
                                // Peer was seen recently, keeping both
                            }
                        }
                    }
                    
                    // Remove stale peer IDs
                    for stalePeerID in stalePeerIDs {
                        // Removing stale peer
                        self.peerNicknames.removeValue(forKey: stalePeerID)
                        
                        // Also remove from active peers
                        self.activePeers.remove(stalePeerID)
                        
                        // Remove from announced peers
                        self.announcedPeers.remove(stalePeerID)
                        self.announcedToPeers.remove(stalePeerID)
                        
                        // Clear tracking data
                        self.lastHeardFromPeer.removeValue(forKey: stalePeerID)
                        
                        // Disconnect any peripherals associated with stale ID
                        if let peripheral = self.connectedPeripherals[stalePeerID] {
                            self.intentionalDisconnects.insert(peripheral.identifier.uuidString)
                            self.centralManager?.cancelPeripheralConnection(peripheral)
                            self.connectedPeripherals.removeValue(forKey: stalePeerID)
                            self.peripheralCharacteristics.removeValue(forKey: peripheral)
                        }
                        
                        // Remove RSSI data
                        self.peerRSSI.removeValue(forKey: stalePeerID)
                        
                        // Clear cached messages tracking
                        self.cachedMessagesSentToPeer.remove(stalePeerID)
                        
                        // Remove from last seen timestamps
                        self.peerLastSeenTimestamps.remove(stalePeerID)
                        
                        // No longer tracking key exchanges
                    }
                    
                    // If we had stale peers, notify the UI immediately
                    if !stalePeerIDs.isEmpty {
                        DispatchQueue.main.async { [weak self] in
                            self?.notifyPeerListUpdate(immediate: true)
                        }
                    }
                    
                    // Now add the new peer ID with the nickname
                    self.peerNicknames[senderID] = nickname
                }
                
                // Update peripheral mapping if we have it
                if let peripheral = peripheral {
                    // Find and remove any temp ID mapping for this peripheral
                    var tempIDToRemove: String? = nil
                    for (id, per) in self.connectedPeripherals {
                        if per == peripheral && id != senderID {
                            tempIDToRemove = id
                            break
                        }
                    }
                    
                    if let tempID = tempIDToRemove {
                        // Remove temp mapping
                        self.connectedPeripherals.removeValue(forKey: tempID)
                        // Add real peer ID mapping
                        self.connectedPeripherals[senderID] = peripheral
                        // Update peripheral ID to peer ID mapping
                        self.peerIDByPeripheralID[peripheral.identifier.uuidString] = senderID
                        
                        // IMPORTANT: Remove old peer ID from activePeers to prevent duplicates
                        collectionsQueue.sync(flags: .barrier) {
                            if self.activePeers.contains(tempID) {
                                _ = self.activePeers.remove(tempID)
                            }
                        }
                        
                        // Don't notify about disconnect - this is just cleanup of temporary ID
                    }
                }
                
                // Add to active peers if not already there
                if senderID != "unknown" && senderID != self.myPeerID {
                    // Check for duplicate nicknames and remove old peer IDs
                    collectionsQueue.sync(flags: .barrier) {
                        // Find any existing peers with the same nickname
                        var oldPeerIDsToRemove: [String] = []
                        for existingPeerID in self.activePeers {
                            if existingPeerID != senderID {
                                let existingNickname = self.peerNicknames[existingPeerID] ?? ""
                                if existingNickname == nickname && !existingNickname.isEmpty && existingNickname != "unknown" {
                                    oldPeerIDsToRemove.append(existingPeerID)
                                }
                            }
                        }
                        
                        // Remove old peer IDs with same nickname
                        for oldPeerID in oldPeerIDsToRemove {
                            self.activePeers.remove(oldPeerID)
                            self.peerNicknames.removeValue(forKey: oldPeerID)
                            self.connectedPeripherals.removeValue(forKey: oldPeerID)
                            
                            // Don't notify about disconnect - this is just cleanup of duplicate
                        }
                    }
                    
                    let wasInserted = collectionsQueue.sync(flags: .barrier) {
                        // Final safety check
                        if senderID == self.myPeerID {
                            SecureLogger.log("Blocked self from being added to activePeers", category: SecureLogger.noise, level: .error)
                            return false
                        }
                        let result = self.activePeers.insert(senderID).inserted
                        return result
                    }
                    if wasInserted {
                        SecureLogger.log("📡 Peer joined network: \(senderID) (\(nickname))", category: SecureLogger.session, level: .info)
                    }
                    
                    // Show join message only for first announce AND if we actually added the peer
                    if isFirstAnnounce && wasInserted {
                        announcedPeers.insert(senderID)
                        
                        // Delay the connect message slightly to allow identity announcement to be processed
                        // This helps ensure fingerprint mappings are available for nickname resolution
                        DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
                            self.delegate?.didConnectToPeer(senderID)
                        }
                        self.notifyPeerListUpdate(immediate: true)
                        
                        // Send network available notification if appropriate
                        let currentNetworkSize = collectionsQueue.sync { self.activePeers.count }
                        if currentNetworkSize > 0 {
                            // Clear empty time since network is active
                            networkBecameEmptyTime = nil
                            
                            if !hasNotifiedNetworkAvailable {
                                // Check if enough time has passed since last notification
                                let now = Date()
                                var shouldSendNotification = true
                                
                                if let lastNotification = lastNetworkNotificationTime {
                                    let timeSinceLastNotification = now.timeIntervalSince(lastNotification)
                                    if timeSinceLastNotification < networkNotificationCooldown {
                                        // Too soon to send another notification
                                        shouldSendNotification = false
                                    }
                                }
                                
                                if shouldSendNotification {
                                    hasNotifiedNetworkAvailable = true
                                    lastNetworkNotificationTime = now
                                    NotificationService.shared.sendNetworkAvailableNotification(peerCount: currentNetworkSize)
                                }
                            }
                        }
                        
                        DispatchQueue.main.async {
                            // Check if this is a favorite peer and send notification
                            // Note: This might not work immediately if key exchange hasn't happened yet
                            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                                guard let self = self else { return }
                                
                                // Check if this is a favorite using their public key fingerprint
                                if let fingerprint = self.noiseService.getPeerFingerprint(senderID) {
                                    if self.delegate?.isFavorite(fingerprint: fingerprint) ?? false {
                                        NotificationService.shared.sendFavoriteOnlineNotification(nickname: nickname)
                                        
                                        // Send any cached messages for this favorite
                                        self.sendCachedMessages(to: senderID)
                                    }
                                }
                            }
                        }
                    } else {
                        // Just update the peer list
                        self.notifyPeerListUpdate()
                    }
                } else {
                }
                
                // Relay announce if TTL > 0
                if packet.ttl > 1 {
                    var relayPacket = packet
                    relayPacket.ttl -= 1
                    
                    // Add small delay to prevent collision
                    let delay = Double.random(in: 0.1...0.3)
                    DispatchQueue.main.asyncAfter(deadline: .now() + delay) { [weak self] in
                        self?.broadcastPacket(relayPacket)
                    }
                }
            } else {
            }
            
        case .leave:
            let senderID = packet.senderID.hexEncodedString()
            // Legacy peer disconnect (keeping for backwards compatibility)
            if String(data: packet.payload, encoding: .utf8) != nil {
                // Remove from active peers with proper locking
                collectionsQueue.sync(flags: .barrier) {
                    let wasRemoved = self.activePeers.remove(senderID) != nil
                    let nickname = self.peerNicknames.removeValue(forKey: senderID) ?? "unknown"
                    
                    if wasRemoved {
                        // Mark as gracefully left to prevent duplicate disconnect message
                        self.gracefullyLeftPeers.insert(senderID)
                        
                        // Remove after a delay to handle race conditions with physical disconnect
                        DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) { [weak self] in
                            self?.gracefullyLeftPeers.remove(senderID)
                        }
                        
                        SecureLogger.log("📴 Peer left network: \(senderID) (\(nickname))", category: SecureLogger.session, level: .info)
                    }
                }
                
                announcedPeers.remove(senderID)
                
                // Show leave message
                DispatchQueue.main.async {
                    self.delegate?.didDisconnectFromPeer(senderID)
                }
                self.notifyPeerListUpdate()
            }
            
        case .fragmentStart, .fragmentContinue, .fragmentEnd:
            // let fragmentTypeStr = packet.type == MessageType.fragmentStart.rawValue ? "START" : 
            //                    (packet.type == MessageType.fragmentContinue.rawValue ? "CONTINUE" : "END")
            
            // Validate fragment has minimum required size
            if packet.payload.count < 13 {
                return
            }
            
            handleFragment(packet, from: peerID)
            
            // Relay fragments if TTL > 0
            var relayPacket = packet
            relayPacket.ttl -= 1
            if relayPacket.ttl > 0 {
                self.broadcastPacket(relayPacket)
            }
            
            
        case .deliveryAck:
            // Handle delivery acknowledgment
            if let recipientIDData = packet.recipientID,
               isPeerIDOurs(recipientIDData.hexEncodedString()) {
                // This ACK is for us
                let senderID = packet.senderID.hexEncodedString()
                // Check if payload is already decrypted (came through Noise)
                    if let ack = DeliveryAck.fromBinaryData(packet.payload) {
                        // Already decrypted - process directly
                        DeliveryTracker.shared.processDeliveryAck(ack)
                        
                        
                        // Notify delegate
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveDeliveryAck(ack)
                        }
                    } else if let ack = DeliveryAck.decode(from: packet.payload) {
                        // Fallback to JSON for backward compatibility
                        DeliveryTracker.shared.processDeliveryAck(ack)
                        
                        // Notify delegate
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveDeliveryAck(ack)
                        }
                    } else {
                        // Try legacy decryption
                        do {
                            let decryptedData = try noiseService.decrypt(packet.payload, from: senderID)
                            if let ack = DeliveryAck.fromBinaryData(decryptedData) {
                                // Process the ACK
                                DeliveryTracker.shared.processDeliveryAck(ack)
                                
                                
                                // Notify delegate
                                DispatchQueue.main.async {
                                    self.delegate?.didReceiveDeliveryAck(ack)
                                }
                            } else if let ack = DeliveryAck.decode(from: decryptedData) {
                                // Fallback to JSON
                                DeliveryTracker.shared.processDeliveryAck(ack)
                                
                                // Notify delegate
                                DispatchQueue.main.async {
                                    self.delegate?.didReceiveDeliveryAck(ack)
                                }
                            }
                        } catch {
                            SecureLogger.log("Failed to decrypt delivery ACK from \(senderID): \(error)", 
                                             category: SecureLogger.encryption, level: .error)
                        }
                    }
            } else if packet.ttl > 0 {
                // Relay the ACK if not for us
                
                // SAFETY CHECK: Never relay unencrypted JSON
                if let jsonCheck = String(data: packet.payload.prefix(1), encoding: .utf8), jsonCheck == "{" {
                    return
                }
                
                var relayPacket = packet
                relayPacket.ttl -= 1
                self.broadcastPacket(relayPacket)
            }
            
        case .readReceipt:
            // Handle read receipt
            if let recipientIDData = packet.recipientID,
               isPeerIDOurs(recipientIDData.hexEncodedString()) {
                // This read receipt is for us
                let senderID = packet.senderID.hexEncodedString()
                SecureLogger.log("Received read receipt from \(senderID)", category: SecureLogger.session, level: .info)
                // Check if payload is already decrypted (came through Noise)
                    if let receipt = ReadReceipt.fromBinaryData(packet.payload) {
                        // Already decrypted - process directly
                        SecureLogger.log("Processing read receipt for message \(receipt.originalMessageID) from \(receipt.readerID)", category: SecureLogger.session, level: .info)
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveReadReceipt(receipt)
                        }
                    } else if let receipt = ReadReceipt.decode(from: packet.payload) {
                        // Fallback to JSON for backward compatibility
                        SecureLogger.log("Processing read receipt (JSON) for message \(receipt.originalMessageID) from \(receipt.readerID)", category: SecureLogger.session, level: .info)
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveReadReceipt(receipt)
                        }
                    } else {
                        // Try legacy decryption
                        do {
                            let decryptedData = try noiseService.decrypt(packet.payload, from: senderID)
                            if let receipt = ReadReceipt.fromBinaryData(decryptedData) {
                                // Process the read receipt
                                DispatchQueue.main.async {
                                    self.delegate?.didReceiveReadReceipt(receipt)
                                }
                            } else if let receipt = ReadReceipt.decode(from: decryptedData) {
                                // Fallback to JSON
                                DispatchQueue.main.async {
                                    self.delegate?.didReceiveReadReceipt(receipt)
                                }
                            }
                        } catch {
                            // Failed to decrypt read receipt - might be from unknown sender
                        }
                    }
            } else if packet.ttl > 0 {
                // Relay the read receipt if not for us
                var relayPacket = packet
                relayPacket.ttl -= 1
                self.broadcastPacket(relayPacket)
            }
            
        case .noiseIdentityAnnounce:
            // Handle Noise identity announcement
            let senderID = packet.senderID.hexEncodedString()
            
            // Check if this identity announce is targeted to someone else
            if let recipientID = packet.recipientID,
               !isPeerIDOurs(recipientID.hexEncodedString()) {
                // Not for us, relay if TTL > 0
                if packet.ttl > 0 {
                    SecureLogger.log("Relaying identity announce packet to \(recipientID.hexEncodedString()), TTL: \(packet.ttl)", 
                                   category: SecureLogger.session, level: .debug)
                    var relayPacket = packet
                    relayPacket.ttl -= 1
                    broadcastPacket(relayPacket)
                }
                return
            }
            
            if senderID != myPeerID && !isPeerIDOurs(senderID) {
                // Create defensive copy and validate
                let payloadCopy = Data(packet.payload)
                
                guard !payloadCopy.isEmpty else {
                    SecureLogger.log("Received empty NoiseIdentityAnnouncement from \(senderID)", category: SecureLogger.noise, level: .error)
                    return
                }
                
                // Decode the announcement
                let announcement: NoiseIdentityAnnouncement?
                if let firstByte = payloadCopy.first, firstByte == 0x7B { // '{' character - JSON
                    announcement = NoiseIdentityAnnouncement.decode(from: payloadCopy) ?? NoiseIdentityAnnouncement.fromBinaryData(payloadCopy)
                } else {
                    announcement = NoiseIdentityAnnouncement.fromBinaryData(payloadCopy) ?? NoiseIdentityAnnouncement.decode(from: payloadCopy)
                }
                
                guard let announcement = announcement else {
                    SecureLogger.log("Failed to decode NoiseIdentityAnnouncement from \(senderID), size: \(payloadCopy.count)", category: SecureLogger.noise, level: .error)
                    return
                }
                
                // Verify the signature using the signing public key
                let timestampData = String(Int64(announcement.timestamp.timeIntervalSince1970 * 1000)).data(using: .utf8)!
                let bindingData = announcement.peerID.data(using: .utf8)! + announcement.publicKey + timestampData
                if !noiseService.verifySignature(announcement.signature, for: bindingData, publicKey: announcement.signingPublicKey) {
                    SecureLogger.log("Signature verification failed for \(senderID)", category: SecureLogger.noise, level: .warning)
                    return  // Reject announcements with invalid signatures
                }
                
                // Calculate fingerprint from public key
                let hash = SHA256.hash(data: announcement.publicKey)
                let fingerprint = hash.map { String(format: "%02x", $0) }.joined()
                
                // Log receipt of identity announce
                SecureLogger.log("Received identity announce from \(announcement.peerID) (\(announcement.nickname))", 
                               category: SecureLogger.noise, level: .info)
                
                // Create the binding
                let binding = PeerIdentityBinding(
                    currentPeerID: announcement.peerID,
                    fingerprint: fingerprint,
                    publicKey: announcement.publicKey,
                    signingPublicKey: announcement.signingPublicKey,
                    nickname: announcement.nickname,
                    bindingTimestamp: announcement.timestamp,
                    signature: announcement.signature
                )
                
                SecureLogger.log("Creating identity binding for \(announcement.peerID) -> \(fingerprint)", category: SecureLogger.security, level: .info)
                
                // Update our mappings
                updatePeerBinding(announcement.peerID, fingerprint: fingerprint, binding: binding)
                
                // Update connection state only if we're not already authenticated
                let currentState = peerConnectionStates[announcement.peerID] ?? .disconnected
                if currentState != .authenticated {
                    updatePeerConnectionState(announcement.peerID, state: .connected)
                }
                
                // Register the peer's public key with ChatViewModel for verification tracking
                DispatchQueue.main.async { [weak self] in
                    (self?.delegate as? ChatViewModel)?.registerPeerPublicKey(peerID: announcement.peerID, publicKeyData: announcement.publicKey)
                }
                
                // If we don't have a session yet, check if we should initiate
                if !noiseService.hasEstablishedSession(with: announcement.peerID) {
                    // Lock rotation during handshake
                    lockRotation()
                    
                    // Use lexicographic comparison as tie-breaker to prevent simultaneous handshakes
                    // Only the peer with the "lower" ID initiates
                    // Use coordinator to determine if we should initiate
                    let shouldInitiate = handshakeCoordinator.determineHandshakeRole(
                        myPeerID: myPeerID,
                        remotePeerID: announcement.peerID
                    ) == .initiator
                    
                    if shouldInitiate {
                        // Add small delay on fresh startup to let connections stabilize
                        let lastConnection = lastConnectionTime[announcement.peerID] ?? Date.distantPast
                        let timeSinceConnection = Date().timeIntervalSince(lastConnection)
                        
                        if timeSinceConnection > 60.0 { // Fresh connection
                            // Delay handshake initiation slightly for connection stability
                            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                                SecureLogger.log("Initiating handshake after identity announce from \(announcement.peerID)", 
                                               category: SecureLogger.noise, level: .info)
                                self?.attemptHandshakeIfNeeded(with: announcement.peerID, forceIfStale: true)
                            }
                        } else {
                            // Quick reconnection, initiate immediately
                            SecureLogger.log("Quick reconnection - initiating handshake with \(announcement.peerID)", 
                                           category: SecureLogger.noise, level: .info)
                            attemptHandshakeIfNeeded(with: announcement.peerID, forceIfStale: true)
                        }
                    } else {
                        // Send our identity back so they know we're ready
                        SecureLogger.log("Responding to identity announce from \(announcement.peerID) with our own", 
                                       category: SecureLogger.noise, level: .info)
                        sendNoiseIdentityAnnounce(to: announcement.peerID)
                    }
                } else {
                    // We already have a session, but ensure ChatViewModel knows about the fingerprint
                    // This handles the case where handshake completed before identity announcement
                    DispatchQueue.main.async { [weak self] in
                        if let publicKeyData = self?.noiseService.getPeerPublicKeyData(announcement.peerID) {
                            (self?.delegate as? ChatViewModel)?.registerPeerPublicKey(peerID: announcement.peerID, publicKeyData: publicKeyData)
                        }
                    }
                }
            }
            
        case .noiseHandshakeInit:
            // Handle incoming Noise handshake initiation
            let senderID = packet.senderID.hexEncodedString()
            SecureLogger.logHandshake("initiation received", peerID: senderID, success: true)
            
            // Check if this handshake is for us or broadcast
            if let recipientID = packet.recipientID,
               !isPeerIDOurs(recipientID.hexEncodedString()) {
                // Not for us, relay if TTL > 0
                if packet.ttl > 0 {
                    SecureLogger.log("Relaying handshake init packet, TTL: \(packet.ttl)", category: SecureLogger.session, level: .debug)
                    var relayPacket = packet
                    relayPacket.ttl -= 1
                    broadcastPacket(relayPacket)
                }
                return
            }
            if !isPeerIDOurs(senderID) {
                // Check if we already have an established session
                if noiseService.hasEstablishedSession(with: senderID) {
                    // Determine who should be initiator based on peer ID comparison
                    let shouldBeInitiator = myPeerID < senderID
                    
                    if shouldBeInitiator {
                        // We should be initiator but peer is initiating - likely they had a session failure
                        SecureLogger.log("Received handshake init from \(senderID) who should be responder - likely session mismatch, clearing and accepting", category: SecureLogger.noise, level: .warning)
                        cleanupPeerCryptoState(senderID)
                    } else {
                        // Check if we've heard from this peer recently
                        let lastHeard = lastHeardFromPeer[senderID] ?? Date.distantPast
                        let timeSinceLastHeard = Date().timeIntervalSince(lastHeard)
                        
                        // Check session validity before clearing
                        let lastSuccess = lastSuccessfulMessageTime[senderID] ?? Date.distantPast
                        let sessionAge = Date().timeIntervalSince(lastSuccess)
                        
                        // If the peer is initiating a handshake despite us having a valid session,
                        // they must have cleared their session for a good reason (e.g., decryption failure).
                        // We should always accept the handshake to re-establish encryption.
                        SecureLogger.log("Received handshake init from \(senderID) with existing session (age: \(Int(sessionAge))s, last heard: \(Int(timeSinceLastHeard))s ago) - accepting to re-establish encryption", 
                                       category: SecureLogger.handshake, level: .info)
                        cleanupPeerCryptoState(senderID)
                    }
                }
                
                // If we have a handshaking session, reset it to allow new handshake
                if noiseService.hasSession(with: senderID) && !noiseService.hasEstablishedSession(with: senderID) {
                    SecureLogger.log("Received handshake init from \(senderID) while already handshaking - resetting to allow new handshake", category: SecureLogger.noise, level: .info)
                    cleanupPeerCryptoState(senderID)
                }
                
                // Check if we've completed version negotiation with this peer
                if negotiatedVersions[senderID] == nil {
                    // Legacy peer - assume version 1 for backward compatibility
                    SecureLogger.log("Received Noise handshake from \(senderID) without version negotiation, assuming v1", 
                                      category: SecureLogger.session, level: .debug)
                    negotiatedVersions[senderID] = 1
                    versionNegotiationState[senderID] = .ackReceived(version: 1)
                }
                handleNoiseHandshakeMessage(from: senderID, message: packet.payload, isInitiation: true)
                
                // Send protocol ACK for successfully processed handshake initiation
                sendProtocolAck(for: packet, to: senderID)
            }
            
        case .noiseHandshakeResp:
            // Handle Noise handshake response
            let senderID = packet.senderID.hexEncodedString()
            SecureLogger.logHandshake("response received", peerID: senderID, success: true)
            
            // Check if this handshake response is for us
            if let recipientID = packet.recipientID {
                let recipientIDStr = recipientID.hexEncodedString()
                SecureLogger.log("Response targeted to: \(recipientIDStr), is us: \(isPeerIDOurs(recipientIDStr))", category: SecureLogger.noise, level: .debug)
                if !isPeerIDOurs(recipientIDStr) {
                    // Not for us, relay if TTL > 0
                    if packet.ttl > 0 {
                        SecureLogger.log("Relaying handshake response packet, TTL: \(packet.ttl)", category: SecureLogger.session, level: .debug)
                        var relayPacket = packet
                        relayPacket.ttl -= 1
                        broadcastPacket(relayPacket)
                    }
                    return
                }
            }
            
            if !isPeerIDOurs(senderID) {
                // Check our current handshake state
                let currentState = handshakeCoordinator.getHandshakeState(for: senderID)
                SecureLogger.log("Processing handshake response from \(senderID), current state: \(currentState)", category: SecureLogger.noise, level: .info)
                
                // Process the response - this could be message 2 or message 3 in the XX pattern
                handleNoiseHandshakeMessage(from: senderID, message: packet.payload, isInitiation: false)
                
                // Send protocol ACK for successfully processed handshake response
                sendProtocolAck(for: packet, to: senderID)
            }
            
        case .noiseEncrypted:
            // Handle Noise encrypted message
            let senderID = packet.senderID.hexEncodedString()
            if !isPeerIDOurs(senderID) {
                _ = packet.recipientID?.hexEncodedString()
                handleNoiseEncryptedMessage(from: senderID, encryptedData: packet.payload, originalPacket: packet)
            }
            
        case .versionHello:
            // Handle version negotiation hello
            let senderID = packet.senderID.hexEncodedString()
            if !isPeerIDOurs(senderID) {
                handleVersionHello(from: senderID, data: packet.payload, peripheral: peripheral)
            }
            
        case .versionAck:
            // Handle version negotiation acknowledgment
            let senderID = packet.senderID.hexEncodedString()
            if !isPeerIDOurs(senderID) {
                handleVersionAck(from: senderID, data: packet.payload)
            }
            
        case .protocolAck:
            // Handle protocol-level acknowledgment
            let senderID = packet.senderID.hexEncodedString()
            if !isPeerIDOurs(senderID) {
                handleProtocolAck(from: senderID, data: packet.payload)
            }
            
        case .protocolNack:
            // Handle protocol-level negative acknowledgment
            let senderID = packet.senderID.hexEncodedString()
            if !isPeerIDOurs(senderID) {
                handleProtocolNack(from: senderID, data: packet.payload)
            }
            
        case .systemValidation:
            // Handle system validation ping (for session sync verification)
            let senderID = packet.senderID.hexEncodedString()
            if !isPeerIDOurs(senderID) {
                // Try to decrypt the validation ping
                do {
                    let decrypted = try noiseService.decrypt(packet.payload, from: senderID)
                    SecureLogger.log("Successfully validated session with \(senderID) - ping: \(String(data: decrypted, encoding: .utf8) ?? "?")", 
                                   category: SecureLogger.session, level: .debug)
                    
                    // Session is valid, update last successful message time
                    lastSuccessfulMessageTime[senderID] = Date()
                } catch {
                    // Validation failed - session is out of sync
                    SecureLogger.log("Session validation failed with \(senderID): \(error)", 
                                   category: SecureLogger.session, level: .warning)
                    
                    // Send NACK to trigger session re-establishment
                    sendProtocolNack(for: packet, to: senderID, 
                                   reason: "Session validation failed", 
                                   errorCode: .decryptionFailed)
                }
            }
            
        default:
            break
        }
        }
    }
    
    private func sendFragmentedPacket(_ packet: BitchatPacket) {
        guard let fullData = packet.toBinaryData() else { return }
        
        // Generate a fixed 8-byte fragment ID
        var fragmentID = Data(count: 8)
        fragmentID.withUnsafeMutableBytes { bytes in
            arc4random_buf(bytes.baseAddress, 8)
        }
        
        let fragments = stride(from: 0, to: fullData.count, by: maxFragmentSize).map { offset in
            fullData[offset..<min(offset + maxFragmentSize, fullData.count)]
        }
        
        // Splitting into fragments
        
        // Optimize fragment transmission for speed
        // Use minimal delay for BLE 5.0 which supports better throughput
        let delayBetweenFragments: TimeInterval = 0.02  // 20ms between fragments for faster transmission
        
        for (index, fragmentData) in fragments.enumerated() {
            var fragmentPayload = Data()
            
            // Fragment header: fragmentID (8) + index (2) + total (2) + originalType (1) + data
            fragmentPayload.append(fragmentID)
            fragmentPayload.append(UInt8((index >> 8) & 0xFF))
            fragmentPayload.append(UInt8(index & 0xFF))
            fragmentPayload.append(UInt8((fragments.count >> 8) & 0xFF))
            fragmentPayload.append(UInt8(fragments.count & 0xFF))
            fragmentPayload.append(packet.type)
            fragmentPayload.append(fragmentData)
            
            let fragmentType: MessageType
            if index == 0 {
                fragmentType = .fragmentStart
            } else if index == fragments.count - 1 {
                fragmentType = .fragmentEnd
            } else {
                fragmentType = .fragmentContinue
            }
            
            let fragmentPacket = BitchatPacket(
                type: fragmentType.rawValue,
                senderID: packet.senderID,  // Use original packet's senderID (already Data)
                recipientID: packet.recipientID,  // Preserve recipient if any
                timestamp: packet.timestamp,  // Use original timestamp
                payload: fragmentPayload,
                signature: nil,  // Fragments don't need signatures
                ttl: packet.ttl
            )
            
            // Send fragments with linear delay
            let totalDelay = Double(index) * delayBetweenFragments
            
            // Send fragments on background queue with calculated delay
            messageQueue.asyncAfter(deadline: .now() + totalDelay) { [weak self] in
                self?.broadcastPacket(fragmentPacket)
            }
        }
        
        let _ = Double(fragments.count - 1) * delayBetweenFragments
    }
    
    private func handleFragment(_ packet: BitchatPacket, from peerID: String) {
        // Handling fragment
        
        guard packet.payload.count >= 13 else { 
            return 
        }
        
        // Convert to array for safer access
        let payloadArray = Array(packet.payload)
        var offset = 0
        
        // Extract fragment ID as binary data (8 bytes)
        guard payloadArray.count >= 8 else {
            return
        }
        
        let fragmentIDData = Data(payloadArray[0..<8])
        let fragmentID = fragmentIDData.hexEncodedString()
        offset = 8
        
        // Safely extract index
        guard payloadArray.count >= offset + 2 else { 
            // Not enough data for index
            return 
        }
        let index = Int(payloadArray[offset]) << 8 | Int(payloadArray[offset + 1])
        offset += 2
        
        // Safely extract total
        guard payloadArray.count >= offset + 2 else { 
            // Not enough data for total
            return 
        }
        let total = Int(payloadArray[offset]) << 8 | Int(payloadArray[offset + 1])
        offset += 2
        
        // Safely extract original type
        guard payloadArray.count >= offset + 1 else { 
            // Not enough data for type
            return 
        }
        let originalType = payloadArray[offset]
        offset += 1
        
        // Extract fragment data
        let fragmentData: Data
        if payloadArray.count > offset {
            fragmentData = Data(payloadArray[offset...])
        } else {
            fragmentData = Data()
        }
        
        
        // Initialize fragment collection if needed
        if incomingFragments[fragmentID] == nil {
            // Check if we've reached the concurrent session limit
            if incomingFragments.count >= maxConcurrentFragmentSessions {
                // Clean up oldest fragments first
                cleanupOldFragments()
                
                // If still at limit, reject new session to prevent DoS
                if incomingFragments.count >= maxConcurrentFragmentSessions {
                    return
                }
            }
            
            incomingFragments[fragmentID] = [:]
            fragmentMetadata[fragmentID] = (originalType, total, Date())
        }
        
        incomingFragments[fragmentID]?[index] = fragmentData
        
        
        // Check if we have all fragments
        if let fragments = incomingFragments[fragmentID],
           fragments.count == total {
            
            // Reassemble the original packet
            var reassembledData = Data()
            for i in 0..<total {
                if let fragment = fragments[i] {
                    reassembledData.append(fragment)
                } else {
                    // Missing fragment
                    return
                }
            }
            
            // Successfully reassembled fragments
            
            // Parse and handle the reassembled packet
            if let reassembledPacket = BitchatPacket.from(reassembledData) {
                // Clean up
                incomingFragments.removeValue(forKey: fragmentID)
                fragmentMetadata.removeValue(forKey: fragmentID)
                
                // Handle the reassembled packet
                handleReceivedPacket(reassembledPacket, from: peerID, peripheral: nil)
            }
        }
        
        // Periodic cleanup of old fragments
        cleanupOldFragments()
    }
    
    private func cleanupOldFragments() {
        let cutoffTime = Date().addingTimeInterval(-fragmentTimeout)
        var fragmentsToRemove: [String] = []
        
        for (fragID, metadata) in fragmentMetadata {
            if metadata.timestamp < cutoffTime {
                fragmentsToRemove.append(fragID)
            }
        }
        
        // Remove expired fragments
        for fragID in fragmentsToRemove {
            incomingFragments.removeValue(forKey: fragID)
            fragmentMetadata.removeValue(forKey: fragID)
        }
        
        // Also enforce memory bounds - if we have too many fragment bytes, remove oldest
        var totalFragmentBytes = 0
        let maxFragmentBytes = 10 * 1024 * 1024  // 10MB max for all fragments
        
        for (_, fragments) in incomingFragments {
            for (_, data) in fragments {
                totalFragmentBytes += data.count
            }
        }
        
        if totalFragmentBytes > maxFragmentBytes {
            // Remove oldest fragments until under limit
            let sortedFragments = fragmentMetadata.sorted { $0.value.timestamp < $1.value.timestamp }
            for (fragID, _) in sortedFragments {
                incomingFragments.removeValue(forKey: fragID)
                fragmentMetadata.removeValue(forKey: fragID)
                
                // Recalculate total
                totalFragmentBytes = 0
                for (_, fragments) in incomingFragments {
                    for (_, data) in fragments {
                        totalFragmentBytes += data.count
                    }
                }
                
                if totalFragmentBytes <= maxFragmentBytes {
                    break
                }
            }
        }
    }
}

extension BluetoothMeshService: CBCentralManagerDelegate {
    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        // Central manager state updated
        switch central.state {
        case .unknown: break
        case .resetting: break
        case .unsupported: break
        case .unauthorized: break
        case .poweredOff: break
        case .poweredOn: break
        @unknown default: break
        }
        
        if central.state == .unsupported {
        } else if central.state == .unauthorized {
        } else if central.state == .poweredOff {
        } else if central.state == .poweredOn {
            startScanning()
            
            // Send announces when central manager is ready
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                self?.sendBroadcastAnnounce()
            }
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
        // Optimize for 300m range - only connect to strong enough signals
        let rssiValue = RSSI.intValue
        
        // Filter out very weak signals (below -90 dBm) to save battery
        guard rssiValue > -90 else { 
            // Ignoring peripheral due to very weak signal
            return 
        }
        
        // Throttle RSSI updates to save CPU
        let peripheralID = peripheral.identifier.uuidString
        if let lastUpdate = lastRSSIUpdate[peripheralID],
           Date().timeIntervalSince(lastUpdate) < 1.0 {
            return  // Skip update if less than 1 second since last update
        }
        lastRSSIUpdate[peripheralID] = Date()
        
        // Store RSSI by peripheral ID for later use
        peripheralRSSI[peripheralID] = RSSI
        
        // Extract peer ID from name (no prefix for stealth)
        // Peer IDs are 8 bytes = 16 hex characters
        if let name = peripheral.name, name.count == 16 {
            // Assume 16-character hex names are peer IDs
            let peerID = name
            
            // Don't process our own advertisements (including previous peer IDs)
            if isPeerIDOurs(peerID) {
                return
            }
            
            // Validate RSSI before storing
            let rssiValue = RSSI.intValue
            if rssiValue != 127 && rssiValue >= -100 && rssiValue <= 0 {
                peerRSSI[peerID] = RSSI
            }
            // Discovered potential peer
            SecureLogger.log("Discovered peer with ID: \(peerID), self ID: \(myPeerID)", category: SecureLogger.noise, level: .debug)
        }
        
        // Connection pooling with exponential backoff
        // peripheralID already declared above
        
        // Check if we should attempt connection (considering backoff)
        if let backoffTime = connectionBackoff[peripheralID],
           Date().timeIntervalSince1970 < backoffTime {
            // Still in backoff period, skip connection
            return
        }
        
        // Check if we already have this peripheral in our pool
        if let pooledPeripheral = connectionPool[peripheralID] {
            // Reuse existing peripheral from pool
            if pooledPeripheral.state == CBPeripheralState.disconnected {
                // Reconnect if disconnected
                central.connect(pooledPeripheral, options: [
                    CBConnectPeripheralOptionNotifyOnConnectionKey: true,
                    CBConnectPeripheralOptionNotifyOnDisconnectionKey: true,
                    CBConnectPeripheralOptionNotifyOnNotificationKey: true
                ])
            }
            return
        }
        
        // New peripheral - add to pool and connect
        if !discoveredPeripherals.contains(peripheral) {
            // Check connection pool limits
            let connectedCount = connectionPool.values.filter { $0.state == .connected }.count
            if connectedCount >= maxConnectedPeripherals {
                // Connection pool is full - find least recently used peripheral to disconnect
                if let lruPeripheralID = findLeastRecentlyUsedPeripheral() {
                    if let lruPeripheral = connectionPool[lruPeripheralID] {
                        SecureLogger.log("Connection pool full, disconnecting LRU peripheral: \(lruPeripheralID)", 
                                       category: SecureLogger.session, level: .debug)
                        central.cancelPeripheralConnection(lruPeripheral)
                        connectionPool.removeValue(forKey: lruPeripheralID)
                    }
                }
            }
            
            discoveredPeripherals.append(peripheral)
            peripheral.delegate = self
            connectionPool[peripheralID] = peripheral
            
            // Track connection attempts
            let attempts = connectionAttempts[peripheralID] ?? 0
            connectionAttempts[peripheralID] = attempts + 1
            
            // Only attempt if under max attempts
            if attempts < maxConnectionAttempts {
                // Use optimized connection parameters for better range
                let connectionOptions: [String: Any] = [
                    CBConnectPeripheralOptionNotifyOnConnectionKey: true,
                    CBConnectPeripheralOptionNotifyOnDisconnectionKey: true,
                    CBConnectPeripheralOptionNotifyOnNotificationKey: true
                ]
                
                central.connect(peripheral, options: connectionOptions)
            }
        }
    }
    
    func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
        let tempID = peripheral.identifier.uuidString
        SecureLogger.log("Peripheral connected: \(tempID)", category: SecureLogger.session, level: .info)
        
        // Log current mapping state for debugging
        SecureLogger.log("Current peerIDByPeripheralID mappings: \(peerIDByPeripheralID.keys.joined(separator: ", "))", 
                       category: SecureLogger.session, level: .debug)
        
        peripheral.delegate = self
        peripheral.discoverServices([BluetoothMeshService.serviceUUID])
        
        // Store peripheral by its system ID temporarily until we get the real peer ID
        connectedPeripherals[tempID] = peripheral
        
        // Update connection state to connected (but not authenticated yet)
        // We don't know the real peer ID yet, so we can't update the state
        
        // Don't show connected message yet - wait for key exchange
        // This prevents the connect/disconnect/connect pattern
        
        // Request RSSI reading
        peripheral.readRSSI()
        
        // iOS 11+ BLE 5.0: Request 2M PHY for better range and speed
        if #available(iOS 11.0, macOS 10.14, *) {
            // 2M PHY provides better range than 1M PHY
            // This is a hint - system will use best available
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
        let peripheralID = peripheral.identifier.uuidString
        
        // Check if this was an intentional disconnect
        if intentionalDisconnects.contains(peripheralID) {
            intentionalDisconnects.remove(peripheralID)
            SecureLogger.log("Intentional disconnect: \(peripheralID)", category: SecureLogger.session, level: .debug)
            // Don't process this disconnect further
            return
        }
        
        // Log disconnect with error if present
        if let error = error {
            SecureLogger.logError(error, context: "Peripheral disconnected: \(peripheralID)", category: SecureLogger.session)
        } else {
            SecureLogger.log("Peripheral disconnected normally: \(peripheralID)", category: SecureLogger.session, level: .info)
        }
        
        // Find the real peer ID for this peripheral
        var realPeerID: String? = nil
        
        // First check our peripheral ID to peer ID mapping
        if let peerID = peerIDByPeripheralID[peripheralID] {
            realPeerID = peerID
            SecureLogger.log("Found peer ID \(peerID) from peerIDByPeripheralID for peripheral \(peripheralID)", 
                           category: SecureLogger.session, level: .debug)
        } else {
            SecureLogger.log("No mapping in peerIDByPeripheralID for peripheral \(peripheralID), checking connectedPeripherals", 
                           category: SecureLogger.session, level: .debug)
            
            // Fallback: check if we have a direct mapping from peripheral to peer ID
            for (peerID, connectedPeripheral) in connectedPeripherals {
                if connectedPeripheral.identifier == peripheral.identifier {
                    // Check if this is a real peer ID (16 hex chars) not a temp ID
                    if peerID.count == 16 && peerID.allSatisfy({ $0.isHexDigit }) {
                        realPeerID = peerID
                        SecureLogger.log("Found peer ID \(peerID) from connectedPeripherals fallback", 
                                       category: SecureLogger.session, level: .debug)
                        break
                    } else {
                        SecureLogger.log("Skipping non-peer ID '\(peerID)' (length: \(peerID.count))", 
                                       category: SecureLogger.session, level: .debug)
                    }
                }
            }
        }
        
        // Update connection state immediately if we have a real peer ID
        if let peerID = realPeerID {
            // Update peer connection state
            updatePeerConnectionState(peerID, state: .disconnected)
            
            // Clear pending messages for disconnected peer to prevent retry loops
            collectionsQueue.async(flags: .barrier) { [weak self] in
                if let pendingCount = self?.pendingPrivateMessages[peerID]?.count, pendingCount > 0 {
                    SecureLogger.log("Clearing \(pendingCount) pending messages for disconnected peer \(peerID)", 
                                   category: SecureLogger.session, level: .info)
                    self?.pendingPrivateMessages[peerID]?.removeAll()
                }
            }
            
            // Reset handshake state to prevent stuck handshakes
            handshakeCoordinator.resetHandshakeState(for: peerID)
            
            // Notify delegate immediately about disconnect (unless peer gracefully left)
            if !gracefullyLeftPeers.contains(peerID) {
                DispatchQueue.main.async {
                    self.delegate?.didDisconnectFromPeer(peerID)
                }
            }
        }
        
        // Implement exponential backoff for failed connections
        if error != nil {
            let attempts = connectionAttempts[peripheralID] ?? 0
            if attempts >= maxConnectionAttempts {
                // Max attempts reached, apply long backoff
                let backoffDuration = baseBackoffInterval * pow(2.0, Double(attempts))
                connectionBackoff[peripheralID] = Date().timeIntervalSince1970 + backoffDuration
            }
        } else {
            // Clean disconnect, reset attempts
            connectionAttempts[peripheralID] = 0
            connectionBackoff.removeValue(forKey: peripheralID)
        }
        
        // Clean up peripheral tracking
        peerIDByPeripheralID.removeValue(forKey: peripheralID)
        lastActivityByPeripheralID.removeValue(forKey: peripheralID)
        
        // Find peer ID for this peripheral (could be temp ID or real ID)
        var foundPeerID: String? = nil
        for (id, per) in connectedPeripherals {
            if per == peripheral {
                foundPeerID = id
                break
            }
        }
        
        if let peerID = foundPeerID {
            connectedPeripherals.removeValue(forKey: peerID)
            peripheralCharacteristics.removeValue(forKey: peripheral)
            
            // Don't clear Noise session on disconnect - sessions should survive disconnects
            // The Noise protocol is designed to maintain sessions across network interruptions
            // Only clear sessions on authentication failure
            if peerID.count == 16 {  // Real peer ID
                // Clear connection time and last heard tracking on disconnect to properly detect stale sessions
                lastConnectionTime.removeValue(forKey: peerID)
                lastHeardFromPeer.removeValue(forKey: peerID)
                // Keep lastSuccessfulMessageTime to validate session on reconnect
                let lastSuccess = lastSuccessfulMessageTime[peerID] ?? Date.distantPast
                let sessionAge = Date().timeIntervalSince(lastSuccess)
                SecureLogger.log("Peer disconnected: \(peerID), keeping Noise session (age: \(Int(sessionAge))s)", category: SecureLogger.noise, level: .info)
            }
            
            // Only remove from active peers if it's not a temp ID
            // Temp IDs shouldn't be in activePeers anyway
            let (removed, _) = collectionsQueue.sync(flags: .barrier) {
                var removed = false
                if peerID.count == 16 {  // Real peer ID (8 bytes = 16 hex chars)
                    removed = activePeers.remove(peerID) != nil
                    if removed {
                        // Only log disconnect if peer didn't gracefully leave
                        if !self.gracefullyLeftPeers.contains(peerID) {
                            let nickname = self.peerNicknames[peerID] ?? "unknown"
                            SecureLogger.log("📴 Peer disconnected from network: \(peerID) (\(nickname))", category: SecureLogger.session, level: .info)
                        } else {
                            // Peer gracefully left, just clean up the tracking
                            self.gracefullyLeftPeers.remove(peerID)
                        }
                    }
                    
                    _ = announcedPeers.remove(peerID)
                    _ = announcedToPeers.remove(peerID)
                } else {
                }
                
                // Clear cached messages tracking for this peer to allow re-sending if they reconnect
                cachedMessagesSentToPeer.remove(peerID)
                
                // Clear version negotiation state
                versionNegotiationState.removeValue(forKey: peerID)
                negotiatedVersions.removeValue(forKey: peerID)
                
                // Peer disconnected
                
                return (removed, peerNicknames[peerID])
            }
            
            // Always notify peer list update on disconnect, regardless of whether peer was in activePeers
            // This ensures UI stays in sync even if there was a state mismatch
            self.notifyPeerListUpdate(immediate: true)
            
            if removed {
                // Mark when network became empty, but don't reset flag immediately
                let currentNetworkSize = collectionsQueue.sync { activePeers.count }
                if currentNetworkSize == 0 && networkBecameEmptyTime == nil {
                    networkBecameEmptyTime = Date()
                }
            }
        }
        
        // Keep in pool but remove from discovered list
        discoveredPeripherals.removeAll { $0 == peripheral }
        
        // Continue scanning for reconnection
        if centralManager?.state == .poweredOn {
            // Stop and restart to ensure clean state
            centralManager?.stopScan()
            centralManager?.scanForPeripherals(withServices: [BluetoothMeshService.serviceUUID], options: [CBCentralManagerScanOptionAllowDuplicatesKey: false])
        }
    }
}

extension BluetoothMeshService: CBPeripheralDelegate {
    func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
        if let error = error {
            SecureLogger.log("Error discovering services: \(error)", 
                             category: SecureLogger.encryption, level: .error)
            return
        }
        
        guard let services = peripheral.services else { return }
        
        
        for service in services {
            peripheral.discoverCharacteristics([BluetoothMeshService.characteristicUUID], for: service)
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
        if let error = error {
            SecureLogger.log("Error discovering characteristics: \(error)", 
                             category: SecureLogger.encryption, level: .error)
            return
        }
        
        guard let characteristics = service.characteristics else { return }
        
        
        for characteristic in characteristics {
            if characteristic.uuid == BluetoothMeshService.characteristicUUID {
                peripheral.setNotifyValue(true, for: characteristic)
                peripheralCharacteristics[peripheral] = characteristic
                
                // Request maximum MTU for faster data transfer
                // iOS supports up to 512 bytes with BLE 5.0
                peripheral.maximumWriteValueLength(for: .withoutResponse)
                
                // Start version negotiation instead of immediately sending Noise identity
                self.sendVersionHello(to: peripheral)
                
                // Send announce packet after version negotiation completes
                // Send multiple times for reliability
                if let vm = self.delegate as? ChatViewModel {
                    // Send announces multiple times with delays
                    for delay in [0.3, 0.8, 1.5] {
                        DispatchQueue.main.asyncAfter(deadline: .now() + delay) { [weak self] in
                            guard let self = self else { return }
                            let announcePacket = BitchatPacket(
                                type: MessageType.announce.rawValue,
                                ttl: 3,
                                senderID: self.myPeerID,
                                payload: Data(vm.nickname.utf8)
                            )
                            self.broadcastPacket(announcePacket)
                        }
                    }
                    
                    // Also send targeted announce to this specific peripheral
                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) { [weak self, weak peripheral] in
                        guard let self = self,
                              let peripheral = peripheral,
                              peripheral.state == .connected,
                              let characteristic = peripheral.services?.first(where: { $0.uuid == BluetoothMeshService.serviceUUID })?.characteristics?.first(where: { $0.uuid == BluetoothMeshService.characteristicUUID }) else { return }
                        
                        let announcePacket = BitchatPacket(
                            type: MessageType.announce.rawValue,
                            ttl: 3,
                            senderID: self.myPeerID,
                            payload: Data(vm.nickname.utf8)
                        )
                        if let data = announcePacket.toBinaryData() {
                            self.writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: nil)
                        }
                    }
                }
            }
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
        guard let data = characteristic.value else {
            return
        }
        
        // Update activity tracking for this peripheral
        updatePeripheralActivity(peripheral.identifier.uuidString)
        
        
        guard let packet = BitchatPacket.from(data) else { 
            return 
        }
        
        
        // Use the sender ID from the packet, not our local mapping which might still be a temp ID
        let _ = connectedPeripherals.first(where: { $0.value == peripheral })?.key ?? "unknown"
        let packetSenderID = packet.senderID.hexEncodedString()
        
        
        // Always handle received packets
        handleReceivedPacket(packet, from: packetSenderID, peripheral: peripheral)
    }
    
    func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
        if let error = error {
            // Log error but don't spam for common errors
            let errorCode = (error as NSError).code
            if errorCode != 242 { // Don't log the common "Unknown ATT error"
            }
        } else {
        }
    }
    
    func peripheral(_ peripheral: CBPeripheral, didModifyServices invalidatedServices: [CBService]) {
        peripheral.discoverServices([BluetoothMeshService.serviceUUID])
    }
    
    func peripheral(_ peripheral: CBPeripheral, didUpdateNotificationStateFor characteristic: CBCharacteristic, error: Error?) {
        // Handle notification state updates if needed
    }
    
    func peripheral(_ peripheral: CBPeripheral, didReadRSSI RSSI: NSNumber, error: Error?) {
        guard error == nil else { return }
        
        // Validate RSSI value - 127 means no RSSI available
        let rssiValue = RSSI.intValue
        
        // Only store valid RSSI values
        if rssiValue == 127 || rssiValue < -100 || rssiValue > 0 {
            SecureLogger.log("Invalid RSSI value \(rssiValue) from peripheral, will retry", category: SecureLogger.session, level: .debug)
            
            // Retry sooner if we got an invalid value
            DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { [weak peripheral] in
                guard let peripheral = peripheral, peripheral.state == .connected else { return }
                peripheral.readRSSI()
            }
            return
        }
        
        // Find the peer ID for this peripheral
        if let peerID = connectedPeripherals.first(where: { $0.value == peripheral })?.key {
            // Handle both temp IDs and real peer IDs
            DispatchQueue.main.async { [weak self] in
                guard let self = self else { return }
                
                if peerID.count != 16 {
                    // It's a temp ID, store RSSI temporarily
                    self.peripheralRSSI[peerID] = RSSI
                    // Keep trying to read RSSI until we get real peer ID
                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak peripheral] in
                        guard let peripheral = peripheral, peripheral.state == .connected else { return }
                        peripheral.readRSSI()
                    }
                } else {
                    // It's a real peer ID, store it
                    self.peerRSSI[peerID] = RSSI
                    // Force UI update when we have a real peer ID
                    self.notifyPeerListUpdate()
                }
            }
            
            // Periodically update RSSI
            DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) { [weak peripheral] in
                guard let peripheral = peripheral, peripheral.state == .connected else { return }
                peripheral.readRSSI()
            }
        }
    }
}

extension BluetoothMeshService: CBPeripheralManagerDelegate {
    func peripheralManagerDidUpdateState(_ peripheral: CBPeripheralManager) {
        // Peripheral manager state updated
        switch peripheral.state {
        case .unknown: break
        case .resetting: break
        case .unsupported: break
        case .unauthorized: break
        case .poweredOff: break
        case .poweredOn: break
        @unknown default: break
        }
        
        switch peripheral.state {
        case .unsupported:
            break
        case .unauthorized:
            break
        case .poweredOff:
            break
        case .poweredOn:
            setupPeripheral()
            startAdvertising()
            
            // Send announces when peripheral manager is ready
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                self?.sendBroadcastAnnounce()
            }
        default:
            break
        }
    }
    
    func peripheralManager(_ peripheral: CBPeripheralManager, didAdd service: CBService, error: Error?) {
        // Service added
    }
    
    func peripheralManagerDidStartAdvertising(_ peripheral: CBPeripheralManager, error: Error?) {
        // Advertising state changed
    }
    
    func peripheralManager(_ peripheral: CBPeripheralManager, didReceiveWrite requests: [CBATTRequest]) {
        for request in requests {
            if let data = request.value {
                        
                if let packet = BitchatPacket.from(data) {
                    
                    // Log specific Noise packet types
                    switch packet.type {
                    case MessageType.noiseHandshakeInit.rawValue:
                        break
                    case MessageType.noiseHandshakeResp.rawValue:
                        break
                    case MessageType.noiseEncrypted.rawValue:
                        break
                    default:
                        break
                    }
                    
                    // Try to identify peer from packet
                    let peerID = packet.senderID.hexEncodedString()
                    
                    // Store the central for updates
                if !subscribedCentrals.contains(request.central) {
                    subscribedCentrals.append(request.central)
                }
                
                // Track this peer as connected
                if peerID != "unknown" && peerID != myPeerID {
                    // Double-check we're not adding ourselves
                    if peerID == self.myPeerID {
                        SecureLogger.log("Preventing self from being added as peer (peripheral manager)", category: SecureLogger.noise, level: .warning)
                        peripheral.respond(to: request, withResult: .success)
                        return
                    }
                    
                    // Note: Legacy keyExchange (0x02) no longer handled
                    
                    self.notifyPeerListUpdate()
                }
                
                    handleReceivedPacket(packet, from: peerID)
                    peripheral.respond(to: request, withResult: .success)
                } else {
                    peripheral.respond(to: request, withResult: .invalidPdu)
                }
            } else {
                peripheral.respond(to: request, withResult: .invalidPdu)
            }
        }
    }
    
    func peripheralManager(_ peripheral: CBPeripheralManager, central: CBCentral, didSubscribeTo characteristic: CBCharacteristic) {
        if !subscribedCentrals.contains(central) {
            subscribedCentrals.append(central)
            
            // Send Noise identity announcement to newly connected central
            sendNoiseIdentityAnnounce()
            
            // Update peer list to show we're connected (even without peer ID yet)
            self.notifyPeerListUpdate()
        }
    }
    
    func peripheralManager(_ peripheral: CBPeripheralManager, central: CBCentral, didUnsubscribeFrom characteristic: CBCharacteristic) {
        subscribedCentrals.removeAll { $0 == central }
        
        // Don't aggressively remove peers when centrals unsubscribe
        // Peers may be connected through multiple paths
        
        // Ensure advertising continues for reconnection
        if peripheralManager?.state == .poweredOn && peripheralManager?.isAdvertising == false {
            startAdvertising()
        }
    }
    
    // MARK: - Battery Monitoring
    
    private func setupBatteryOptimizer() {
        // Subscribe to power mode changes
        batteryOptimizer.$currentPowerMode
            .sink { [weak self] powerMode in
                self?.handlePowerModeChange(powerMode)
            }
            .store(in: &batteryOptimizerCancellables)
        
        // Subscribe to battery level changes
        batteryOptimizer.$batteryLevel
            .sink { [weak self] level in
                self?.currentBatteryLevel = level
            }
            .store(in: &batteryOptimizerCancellables)
        
        // Initial update
        handlePowerModeChange(batteryOptimizer.currentPowerMode)
    }
    
    private func handlePowerModeChange(_ powerMode: PowerMode) {
        let params = batteryOptimizer.scanParameters
        activeScanDuration = params.duration
        scanPauseDuration = params.pause
        
        // Update max connections
        let maxConnections = powerMode.maxConnections
        
        // If we have too many connections, disconnect from the least important ones
        if connectedPeripherals.count > maxConnections {
            disconnectLeastImportantPeripherals(keepCount: maxConnections)
        }
        
        // Update message aggregation window
        aggregationWindow = powerMode.messageAggregationWindow
        
        // If we're currently scanning, restart with new parameters
        if scanDutyCycleTimer != nil {
            scanDutyCycleTimer?.invalidate()
            scheduleScanDutyCycle()
        }
        
        // Handle advertising intervals
        if powerMode.advertisingInterval > 0 {
            // Stop continuous advertising and use interval-based
            scheduleAdvertisingCycle(interval: powerMode.advertisingInterval)
        } else {
            // Continuous advertising for performance mode
            startAdvertising()
        }
    }
    
    private func disconnectLeastImportantPeripherals(keepCount: Int) {
        // Disconnect peripherals with lowest activity/importance
        let sortedPeripherals = connectedPeripherals.values
            .sorted { peer1, peer2 in
                // Keep peripherals we've recently communicated with
                let peer1Activity = lastMessageFromPeer.get(peer1.identifier.uuidString) ?? Date.distantPast
                let peer2Activity = lastMessageFromPeer.get(peer2.identifier.uuidString) ?? Date.distantPast
                return peer1Activity > peer2Activity
            }
        
        // Disconnect the least active ones
        let toDisconnect = sortedPeripherals.dropFirst(keepCount)
        for peripheral in toDisconnect {
            centralManager?.cancelPeripheralConnection(peripheral)
        }
    }
    
    private func scheduleAdvertisingCycle(interval: TimeInterval) {
        advertisingTimer?.invalidate()
        
        // Stop advertising
        if isAdvertising {
            peripheralManager?.stopAdvertising()
            isAdvertising = false
        }
        
        // Schedule next advertising burst
        advertisingTimer = Timer.scheduledTimer(withTimeInterval: interval, repeats: true) { [weak self] _ in
            self?.advertiseBurst()
        }
    }
    
    private func advertiseBurst() {
        guard batteryOptimizer.currentPowerMode != .ultraLowPower || !batteryOptimizer.isInBackground else {
            return // Skip advertising in ultra low power + background
        }
        
        startAdvertising()
        
        // Stop advertising after a short burst (1 second)
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { [weak self] in
            if self?.batteryOptimizer.currentPowerMode.advertisingInterval ?? 0 > 0 {
                self?.peripheralManager?.stopAdvertising()
                self?.isAdvertising = false
            }
        }
    }
    
    // Legacy battery monitoring methods - kept for compatibility
    // Now handled by BatteryOptimizer
    private func updateBatteryLevel() {
        // This method is now handled by BatteryOptimizer
        // Keeping empty implementation for compatibility
    }
    
    private func updateScanParametersForBattery() {
        // This method is now handled by BatteryOptimizer through handlePowerModeChange
        // Keeping empty implementation for compatibility
    }
    
    // MARK: - Privacy Utilities
    
    private func randomDelay() -> TimeInterval {
        // Generate random delay between min and max for timing obfuscation
        return TimeInterval.random(in: minMessageDelay...maxMessageDelay)
    }
    
    // MARK: - Cover Traffic
    
    private func startCoverTraffic() {
        // Start cover traffic with random interval
        scheduleCoverTraffic()
    }
    
    private func scheduleCoverTraffic() {
        // Random interval between 30-120 seconds
        let interval = TimeInterval.random(in: 30...120)
        
        coverTrafficTimer?.invalidate()
        coverTrafficTimer = Timer.scheduledTimer(withTimeInterval: interval, repeats: false) { [weak self] _ in
            self?.sendDummyMessage()
            self?.scheduleCoverTraffic() // Schedule next dummy message
        }
    }
    
    private func sendDummyMessage() {
        // Only send dummy messages if we have connected peers
        let peers = getAllConnectedPeerIDs()
        guard !peers.isEmpty else { return }
        
        // Skip if battery is low
        if currentBatteryLevel < 0.2 {
            return
        }
        
        // Pick a random peer to send to
        guard let randomPeer = peers.randomElement() else { return }
        
        // Generate random dummy content
        let dummyContent = generateDummyContent()
        
        // Sending cover traffic
        
        // Send as a private message so it's encrypted
        let recipientNickname = collectionsQueue.sync {
            return peerNicknames[randomPeer] ?? "unknown"
        }
        
        sendPrivateMessage(dummyContent, to: randomPeer, recipientNickname: recipientNickname)
    }
    
    private func generateDummyContent() -> String {
        // Generate realistic-looking dummy messages
        let templates = [
            "hey",
            "ok",
            "got it",
            "sure",
            "sounds good",
            "thanks",
            "np",
            "see you there",
            "on my way",
            "running late",
            "be there soon",
            "👍",
            "✓",
            "meeting at the usual spot",
            "confirmed",
            "roger that"
        ]
        
        // Prefix with dummy marker (will be encrypted)
        return coverTrafficPrefix + (templates.randomElement() ?? "ok")
    }
    
    
    private func updatePeerLastSeen(_ peerID: String) {
        peerLastSeenTimestamps.set(peerID, value: Date())
    }
    
    private func sendPendingPrivateMessages(to peerID: String) {
        messageQueue.async(flags: .barrier) { [weak self] in
            guard let self = self else { return }
            
            // Get pending messages with proper queue synchronization
            let pendingMessages = self.collectionsQueue.sync {
                return self.pendingPrivateMessages[peerID]
            }
            
            guard let messages = pendingMessages else { return }
            
            SecureLogger.log("Sending \(messages.count) pending private messages to \(peerID)", category: SecureLogger.session, level: .info)
            
            // Clear pending messages for this peer
            self.collectionsQueue.sync(flags: .barrier) {
                _ = self.pendingPrivateMessages.removeValue(forKey: peerID)
            }
            
            // Send each pending message
            for (content, recipientNickname, messageID) in messages {
                // Check if this is a read receipt
                if content.hasPrefix("READ_RECEIPT:") {
                    // Extract the original message ID
                    let originalMessageID = String(content.dropFirst("READ_RECEIPT:".count))
                    SecureLogger.log("Sending queued read receipt for message \(originalMessageID) to \(peerID)", category: SecureLogger.session, level: .debug)
                    
                    // Create and send the actual read receipt
                    let receipt = ReadReceipt(
                        originalMessageID: originalMessageID,
                        readerID: self.myPeerID,
                        readerNickname: recipientNickname // This is actually the reader's nickname
                    )
                    
                    // Send the read receipt using the normal method
                    DispatchQueue.global().async { [weak self] in
                        self?.sendReadReceipt(receipt, to: peerID)
                    }
                } else {
                    // Regular message
                    SecureLogger.log("Sending pending message \(messageID) to \(peerID)", category: SecureLogger.session, level: .debug)
                    // Use async to avoid blocking the queue
                    DispatchQueue.global().async { [weak self] in
                        self?.sendPrivateMessage(content, to: peerID, recipientNickname: recipientNickname, messageID: messageID)
                    }
                }
            }
        }
    }
    
    // MARK: - Noise Protocol Support
    
    private func attemptHandshakeIfNeeded(with peerID: String, forceIfStale: Bool = false) {
        // Check if we already have an established session
        if noiseService.hasEstablishedSession(with: peerID) {
            SecureLogger.log("Already have established session with \(peerID), skipping handshake", 
                           category: SecureLogger.handshake, level: .debug)
            return
        }
        
        // Check if we should initiate using the handshake coordinator
        if !handshakeCoordinator.shouldInitiateHandshake(
            myPeerID: myPeerID, 
            remotePeerID: peerID,
            forceIfStale: forceIfStale
        ) {
            SecureLogger.log("Should not initiate handshake with \(peerID) at this time", 
                           category: SecureLogger.handshake, level: .debug)
            return
        }
        
        // Initiate the handshake
        initiateNoiseHandshake(with: peerID)
    }
    
    // Validate an existing Noise session by sending an encrypted ping
    private func validateNoiseSession(with peerID: String) {
        let encryptionQueue = getEncryptionQueue(for: peerID)
        
        encryptionQueue.async { [weak self] in
            guard let self = self else { return }
            
            // Create a ping packet with minimal data
            let pingData = "ping:\(Date().timeIntervalSince1970)".data(using: .utf8)!
            
            do {
                // Try to encrypt a small ping message
                let encrypted = try self.noiseService.encrypt(pingData, for: peerID)
                
                // Create a validation packet (won't be displayed to user)
                let packet = BitchatPacket(
                    type: MessageType.systemValidation.rawValue,
                    senderID: Data(hexString: self.myPeerID) ?? Data(),
                    recipientID: Data(hexString: peerID),
                    timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                    payload: encrypted,
                    signature: nil,
                    ttl: 1
                )
                
                self.broadcastPacket(packet)
                
                SecureLogger.log("Sent session validation ping to \(peerID)", 
                               category: SecureLogger.session, level: .debug)
            } catch {
                // Encryption failed - session is invalid
                SecureLogger.log("Session validation failed for \(peerID): \(error)", 
                               category: SecureLogger.session, level: .warning)
                
                // Clear the invalid session
                self.cleanupPeerCryptoState(peerID)
                
                // Initiate fresh handshake
                DispatchQueue.main.async { [weak self] in
                    self?.attemptHandshakeIfNeeded(with: peerID, forceIfStale: true)
                }
            }
        }
    }
    
    private func initiateNoiseHandshake(with peerID: String) {
        // Use noiseService directly
        
        SecureLogger.log("Initiating Noise handshake with \(peerID)", category: SecureLogger.noise, level: .info)
        
        // Check if we already have an established session
        if noiseService.hasEstablishedSession(with: peerID) {
            SecureLogger.log("Already have established session with \(peerID)", category: SecureLogger.noise, level: .debug)
            // Clear any lingering handshake attempt time
            handshakeAttemptTimes.removeValue(forKey: peerID)
            handshakeCoordinator.recordHandshakeSuccess(peerID: peerID)
            
            // Update connection state to authenticated
            updatePeerConnectionState(peerID, state: .authenticated)
            
            // Force UI update since we have an existing session
            DispatchQueue.main.async { [weak self] in
                (self?.delegate as? ChatViewModel)?.updateEncryptionStatusForPeers()
            }
            
            return
        }
        
        // Check if we have pending messages
        let hasPendingMessages = collectionsQueue.sync {
            return pendingPrivateMessages[peerID]?.isEmpty == false
        }
        
        // Check with coordinator if we should initiate
        if !handshakeCoordinator.shouldInitiateHandshake(myPeerID: myPeerID, remotePeerID: peerID, forceIfStale: hasPendingMessages) {
            SecureLogger.log("Coordinator says we should not initiate handshake with \(peerID)", category: SecureLogger.handshake, level: .debug)
            
            if hasPendingMessages {
                // Check if peer is still connected before retrying
                let connectionState = collectionsQueue.sync { peerConnectionStates[peerID] ?? .disconnected }
                
                if connectionState == .disconnected {
                    // Peer is disconnected - clear pending messages and stop retrying
                    SecureLogger.log("Peer \(peerID) is disconnected, clearing pending messages", category: SecureLogger.handshake, level: .info)
                    collectionsQueue.async(flags: .barrier) { [weak self] in
                        self?.pendingPrivateMessages[peerID]?.removeAll()
                    }
                    handshakeCoordinator.resetHandshakeState(for: peerID)
                } else {
                    // Peer is still connected but handshake is stuck
                    // Send identity announce to prompt them to initiate if they have lower ID
                    SecureLogger.log("Handshake stuck with connected peer \(peerID), sending identity announce", category: SecureLogger.handshake, level: .info)
                    sendNoiseIdentityAnnounce(to: peerID)
                    
                    // Only retry if we haven't retried too many times
                    let retryCount = handshakeCoordinator.getRetryCount(for: peerID)
                    if retryCount < 3 {
                        handshakeCoordinator.incrementRetryCount(for: peerID)
                        DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) { [weak self] in
                            self?.initiateNoiseHandshake(with: peerID)
                        }
                    } else {
                        SecureLogger.log("Max retries reached for \(peerID), clearing pending messages", category: SecureLogger.handshake, level: .warning)
                        collectionsQueue.async(flags: .barrier) { [weak self] in
                            self?.pendingPrivateMessages[peerID]?.removeAll()
                        }
                        handshakeCoordinator.resetHandshakeState(for: peerID)
                    }
                }
            }
            return
        }
        
        // Check if there's a retry delay
        if let retryDelay = handshakeCoordinator.getRetryDelay(for: peerID), retryDelay > 0 {
            SecureLogger.log("Waiting \(retryDelay)s before retrying handshake with \(peerID)", category: SecureLogger.handshake, level: .debug)
            DispatchQueue.main.asyncAfter(deadline: .now() + retryDelay) { [weak self] in
                self?.initiateNoiseHandshake(with: peerID)
            }
            return
        }
        
        // Record that we're initiating
        handshakeCoordinator.recordHandshakeInitiation(peerID: peerID)
        handshakeAttemptTimes[peerID] = Date()
        
        // Update connection state to authenticating
        updatePeerConnectionState(peerID, state: .authenticating)
        
        do {
            // Generate handshake initiation message
            let handshakeData = try noiseService.initiateHandshake(with: peerID)
            SecureLogger.logHandshake("initiated", peerID: peerID, success: true)
            
            // Send handshake initiation
            let packet = BitchatPacket(
                type: MessageType.noiseHandshakeInit.rawValue,
                senderID: Data(hexString: myPeerID) ?? Data(),
                recipientID: Data(hexString: peerID) ?? Data(), // Add recipient ID for targeted delivery
                timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                payload: handshakeData,
                signature: nil,
                ttl: 6 // Increased TTL for better delivery on startup
            )
            
            // Track packet for ACK
            trackPacketForAck(packet)
            
            // Use broadcastPacket instead of sendPacket to ensure it goes through the mesh
            broadcastPacket(packet)
            
            // Schedule a retry check after 5 seconds
            DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) { [weak self] in
                guard let self = self else { return }
                // Check if handshake completed
                if !self.noiseService.hasEstablishedSession(with: peerID) {
                    let state = self.handshakeCoordinator.getHandshakeState(for: peerID)
                    if case .initiating = state {
                        SecureLogger.log("Handshake with \(peerID) not completed after 5s, will retry", category: SecureLogger.handshake, level: .warning)
                        // The handshake coordinator will handle retry logic
                    }
                }
            }
            
        } catch NoiseSessionError.alreadyEstablished {
            // Session already established, no need to handshake
            handshakeCoordinator.recordHandshakeSuccess(peerID: peerID)
        } catch {
            // Failed to initiate handshake
            handshakeCoordinator.recordHandshakeFailure(peerID: peerID, reason: error.localizedDescription)
            SecureLogger.logSecurityEvent(.handshakeFailed(peerID: peerID, error: error.localizedDescription))
        }
    }
    
    private func handleNoiseHandshakeMessage(from peerID: String, message: Data, isInitiation: Bool) {
        // Use noiseService directly
        SecureLogger.logHandshake("processing \(isInitiation ? "init" : "response")", peerID: peerID, success: true)
        
        // Get current handshake state before processing
        let currentState = handshakeCoordinator.getHandshakeState(for: peerID)
        let hasEstablishedSession = noiseService.hasEstablishedSession(with: peerID)
        SecureLogger.log("Current handshake state for \(peerID): \(currentState), hasEstablishedSession: \(hasEstablishedSession)", category: SecureLogger.noise, level: .info)
        
        // Check for duplicate handshake messages
        if handshakeCoordinator.isDuplicateHandshakeMessage(message) {
            SecureLogger.log("Duplicate handshake message from \(peerID), ignoring", category: SecureLogger.handshake, level: .debug)
            return
        }
        
        // If this is an initiation, check if we should accept it
        if isInitiation {
            if !handshakeCoordinator.shouldAcceptHandshakeInitiation(myPeerID: myPeerID, remotePeerID: peerID) {
                SecureLogger.log("Coordinator says we should not accept handshake from \(peerID)", category: SecureLogger.handshake, level: .debug)
                return
            }
            // Record that we're responding
            handshakeCoordinator.recordHandshakeResponse(peerID: peerID)
            
            // Update connection state to authenticating
            updatePeerConnectionState(peerID, state: .authenticating)
        }
        
        do {
            // Process handshake message
            if let response = try noiseService.processHandshakeMessage(from: peerID, message: message) {
                SecureLogger.log("Handshake processing returned response of size \(response.count), sending back to \(peerID)", category: SecureLogger.noise, level: .info)
                
                // Always send responses as handshake response type
                let packet = BitchatPacket(
                    type: MessageType.noiseHandshakeResp.rawValue,
                    senderID: Data(hexString: myPeerID) ?? Data(),
                    recipientID: Data(hexString: peerID) ?? Data(), // Add recipient ID for targeted delivery
                    timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                    payload: response,
                    signature: nil,
                    ttl: 6  // Increased TTL for better delivery on startup
                )
                
                // Track packet for ACK
                trackPacketForAck(packet)
                
                // Use broadcastPacket instead of sendPacket to ensure it goes through the mesh
                broadcastPacket(packet)
            } else {
                SecureLogger.log("No response needed from processHandshakeMessage (isInitiation: \(isInitiation))", category: SecureLogger.noise, level: .debug)
            }
            
            // Check if handshake is complete
            let sessionEstablished = noiseService.hasEstablishedSession(with: peerID)
            let newState = handshakeCoordinator.getHandshakeState(for: peerID)
            SecureLogger.log("After processing handshake message - sessionEstablished: \(sessionEstablished), newState: \(newState)", category: SecureLogger.noise, level: .info)
            
            if sessionEstablished {
                SecureLogger.logSecurityEvent(.handshakeCompleted(peerID: peerID))
                // Unlock rotation now that handshake is complete
                unlockRotation()
                
                // Session established successfully
                handshakeCoordinator.recordHandshakeSuccess(peerID: peerID)
                
                // Update connection state to authenticated
                updatePeerConnectionState(peerID, state: .authenticated)
                
                // Clear handshake attempt time on success
                handshakeAttemptTimes.removeValue(forKey: peerID)
                
                // Initialize last successful message time
                lastSuccessfulMessageTime[peerID] = Date()
                SecureLogger.log("Initialized lastSuccessfulMessageTime for \(peerID)", category: SecureLogger.noise, level: .debug)
                
                // Send identity announcement to this specific peer
                sendNoiseIdentityAnnounce(to: peerID)
                
                // Also broadcast to ensure all peers get it
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                    self?.sendNoiseIdentityAnnounce()
                }
                
                // Send regular announce packet after handshake to trigger connect message
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.8) { [weak self] in
                    self?.sendAnnouncementToPeer(peerID)
                }
                
                // Send any pending private messages
                self.sendPendingPrivateMessages(to: peerID)
                
                // Send any cached store-and-forward messages
                sendCachedMessages(to: peerID)
            }
        } catch NoiseSessionError.alreadyEstablished {
            // Session already established, ignore handshake
            SecureLogger.log("Handshake already established with \(peerID)", category: SecureLogger.noise, level: .info)
            handshakeCoordinator.recordHandshakeSuccess(peerID: peerID)
        } catch {
            // Handshake failed
            handshakeCoordinator.recordHandshakeFailure(peerID: peerID, reason: error.localizedDescription)
            SecureLogger.logSecurityEvent(.handshakeFailed(peerID: peerID, error: error.localizedDescription))
            SecureLogger.log("Handshake failed with \(peerID): \(error)", category: SecureLogger.noise, level: .error)
            
            // If handshake failed due to authentication error, clear the session to allow retry
            if case NoiseError.authenticationFailure = error {
                SecureLogger.log("Handshake failed with \(peerID): authenticationFailure - clearing session", category: SecureLogger.noise, level: .warning)
                cleanupPeerCryptoState(peerID)
            }
        }
    }
    
    private func handleNoiseEncryptedMessage(from peerID: String, encryptedData: Data, originalPacket: BitchatPacket) {
        // Use noiseService directly
        
        // For Noise encrypted messages, we need to decrypt first to check the inner packet
        // The outer packet's recipientID might be for routing, not the final recipient
        
        // Create unique identifier for this encrypted message
        let messageHash = encryptedData.prefix(32).hexEncodedString() // Use first 32 bytes as identifier
        let messageKey = "\(peerID)-\(messageHash)"
        
        // Check if we've already processed this exact encrypted message
        let alreadyProcessed = collectionsQueue.sync(flags: .barrier) {
            if processedNoiseMessages.contains(messageKey) {
                return true
            }
            processedNoiseMessages.insert(messageKey)
            return false
        }
        
        if alreadyProcessed {
            return
        }
        
        do {
            // Decrypt the message
            SecureLogger.log("Attempting to decrypt Noise message from \(peerID), encrypted size: \(encryptedData.count)", category: SecureLogger.encryption, level: .debug)
            let decryptedData = try noiseService.decrypt(encryptedData, from: peerID)
            SecureLogger.log("Successfully decrypted message from \(peerID), decrypted size: \(decryptedData.count)", category: SecureLogger.encryption, level: .debug)
            
            // Update last successful message time
            lastSuccessfulMessageTime[peerID] = Date()
            
            // Send protocol ACK after successful decryption
            sendProtocolAck(for: originalPacket, to: peerID)
            
            // If we can decrypt messages from this peer, they should be in activePeers
            let wasAdded = collectionsQueue.sync(flags: .barrier) {
                if !self.activePeers.contains(peerID) {
                    SecureLogger.log("Adding \(peerID) to activePeers after successful decryption", category: SecureLogger.noise, level: .info)
                    return self.activePeers.insert(peerID).inserted
                }
                return false
            }
            
            if wasAdded {
                // Notify about peer list update
                self.notifyPeerListUpdate()
            }
            
            // Check if this is a special format message (type marker + payload)
            if decryptedData.count > 1 {
                let typeMarker = decryptedData[0]
                
                // Check if this is a delivery ACK with the new format
                if typeMarker == MessageType.deliveryAck.rawValue {
                    // Extract the ACK JSON data (skip the type marker)
                    let ackData = decryptedData.dropFirst()
                    
                    // Decode the delivery ACK - try binary first, then JSON
                    if let ack = DeliveryAck.fromBinaryData(ackData) {
                        SecureLogger.log("Received binary delivery ACK via Noise: \(ack.originalMessageID) from \(ack.recipientNickname)", category: SecureLogger.session, level: .debug)
                        
                        // Process the ACK
                        DeliveryTracker.shared.processDeliveryAck(ack)
                        
                        // Notify delegate
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveDeliveryAck(ack)
                        }
                        return
                    } else if let ack = DeliveryAck.decode(from: ackData) {
                        SecureLogger.log("Received JSON delivery ACK via Noise: \(ack.originalMessageID) from \(ack.recipientNickname)", category: SecureLogger.session, level: .debug)
                        
                        // Process the ACK
                        DeliveryTracker.shared.processDeliveryAck(ack)
                        
                        // Notify delegate
                        DispatchQueue.main.async {
                            self.delegate?.didReceiveDeliveryAck(ack)
                        }
                        return
                    } else {
                        SecureLogger.log("Failed to decode delivery ACK via Noise - data size: \(ackData.count)", category: SecureLogger.session, level: .warning)
                    }
                }
            }
            
            // Try to parse as a full inner packet (for backward compatibility and other message types)
            if let innerPacket = BitchatPacket.from(decryptedData) {
                SecureLogger.log("Successfully parsed inner packet - type: \(MessageType(rawValue: innerPacket.type)?.description ?? "unknown"), from: \(innerPacket.senderID.hexEncodedString()), to: \(innerPacket.recipientID?.hexEncodedString() ?? "broadcast")", category: SecureLogger.session, level: .debug)
                
                // Process the decrypted inner packet
                // The packet will be handled according to its recipient ID
                // If it's for us, it won't be relayed
                handleReceivedPacket(innerPacket, from: peerID)
            } else {
                SecureLogger.log("Failed to parse inner packet from decrypted data", category: SecureLogger.encryption, level: .warning)
            }
        } catch {
            // Failed to decrypt - might need to re-establish session
            SecureLogger.log("Failed to decrypt Noise message from \(peerID): \(error)", category: SecureLogger.encryption, level: .error)
            if !noiseService.hasEstablishedSession(with: peerID) {
                SecureLogger.log("No Noise session with \(peerID), attempting handshake", category: SecureLogger.noise, level: .info)
                attemptHandshakeIfNeeded(with: peerID, forceIfStale: true)
            } else {
                SecureLogger.log("Have session with \(peerID) but decryption failed", category: SecureLogger.encryption, level: .warning)
                
                // Send a NACK to inform peer their session is out of sync
                sendProtocolNack(for: originalPacket, to: peerID, 
                               reason: "Decryption failed - session out of sync", 
                               errorCode: .decryptionFailed)
                
                // The NACK handler will take care of clearing sessions and re-establishing
                // Don't initiate anything here to avoid race conditions
                
                // Update UI to show encryption is broken
                DispatchQueue.main.async { [weak self] in
                    if let chatVM = self?.delegate as? ChatViewModel {
                        chatVM.updateEncryptionStatusForPeer(peerID)
                    }
                }
            }
        }
    }
    
    
    // MARK: - Protocol Version Negotiation
    
    private func handleVersionHello(from peerID: String, data: Data, peripheral: CBPeripheral? = nil) {
        // Create a copy to avoid potential race conditions
        let dataCopy = Data(data)
        
        // Safety check for empty data
        guard !dataCopy.isEmpty else {
            SecureLogger.log("Received empty version hello data from \(peerID)", category: SecureLogger.session, level: .error)
            return
        }
        
        // Check if this peer is reconnecting after disconnect
        if let lastConnected = lastConnectionTime[peerID] {
            let timeSinceLastConnection = Date().timeIntervalSince(lastConnected)
            // Only clear truly stale sessions, not on every reconnect
            if timeSinceLastConnection > 86400.0 { // More than 24 hours since last connection
                // Clear any stale Noise session
                if noiseService.hasEstablishedSession(with: peerID) {
                    SecureLogger.log("Peer \(peerID) reconnecting after \(Int(timeSinceLastConnection))s - clearing stale session", category: SecureLogger.noise, level: .info)
                    cleanupPeerCryptoState(peerID)
                }
            } else if timeSinceLastConnection > 5.0 {
                // Just log the reconnection, don't clear the session
                SecureLogger.log("Peer \(peerID) reconnecting after \(Int(timeSinceLastConnection))s - keeping existing session", category: SecureLogger.noise, level: .info)
            }
        }
        
        // Update last connection time
        lastConnectionTime[peerID] = Date()
        
        // Try JSON first if it looks like JSON
        let hello: VersionHello?
        if let firstByte = dataCopy.first, firstByte == 0x7B { // '{' character
            SecureLogger.log("Version hello from \(peerID) appears to be JSON (size: \(dataCopy.count))", category: SecureLogger.session, level: .debug)
            hello = VersionHello.decode(from: dataCopy) ?? VersionHello.fromBinaryData(dataCopy)
        } else {
            SecureLogger.log("Version hello from \(peerID) appears to be binary (size: \(dataCopy.count), first byte: \(dataCopy.first?.description ?? "nil"))", category: SecureLogger.session, level: .debug)
            hello = VersionHello.fromBinaryData(dataCopy) ?? VersionHello.decode(from: dataCopy)
        }
        
        guard let hello = hello else {
            SecureLogger.log("Failed to decode version hello from \(peerID)", category: SecureLogger.session, level: .error)
            return
        }
        
        SecureLogger.log("Received version hello from \(peerID): supported versions \(hello.supportedVersions), preferred \(hello.preferredVersion)", 
                          category: SecureLogger.session, level: .debug)
        
        // Find the best common version
        let ourVersions = Array(ProtocolVersion.supportedVersions)
        if let agreedVersion = ProtocolVersion.negotiateVersion(clientVersions: hello.supportedVersions, serverVersions: ourVersions) {
            // We can communicate! Send ACK
            SecureLogger.log("Version negotiation agreed with \(peerID): v\(agreedVersion) (client: \(hello.clientVersion), platform: \(hello.platform))", category: SecureLogger.session, level: .info)
            negotiatedVersions[peerID] = agreedVersion
            versionNegotiationState[peerID] = .ackReceived(version: agreedVersion)
            
            let ack = VersionAck(
                agreedVersion: agreedVersion,
                serverVersion: Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "1.0",
                platform: getPlatformString()
            )
            
            sendVersionAck(ack, to: peerID)
            
            // Proceed with Noise handshake after successful version negotiation
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
                guard let self = self else { return }
                
                // First announce our identity
                self.sendNoiseIdentityAnnounce()
                
                // Then check if we should initiate handshake
                // If we already have a valid session, skip handshake
                if self.noiseService.hasEstablishedSession(with: peerID) {
                    SecureLogger.log("Already have session with \(peerID) after version negotiation, skipping handshake", 
                                   category: SecureLogger.handshake, level: .info)
                    
                    // Force a session validation by sending a small encrypted ping
                    self.validateNoiseSession(with: peerID)
                } else {
                    // Use attemptHandshakeIfNeeded to coordinate properly
                    self.attemptHandshakeIfNeeded(with: peerID)
                }
            }
        } else {
            // No compatible version
            SecureLogger.log("Version negotiation failed with \(peerID): No compatible version (client supports: \(hello.supportedVersions))", category: SecureLogger.session, level: .warning)
            versionNegotiationState[peerID] = .failed(reason: "No compatible protocol version")
            
            let ack = VersionAck(
                agreedVersion: 0,
                serverVersion: Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "1.0",
                platform: getPlatformString(),
                rejected: true,
                reason: "No compatible protocol version. Client supports: \(hello.supportedVersions), server supports: \(ourVersions)"
            )
            
            sendVersionAck(ack, to: peerID)
            
            // Disconnect after a short delay
            if let peripheral = peripheral {
                DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) { [weak self] in
                    self?.centralManager?.cancelPeripheralConnection(peripheral)
                }
            }
        }
    }
    
    private func handleVersionAck(from peerID: String, data: Data) {
        // Create a copy to avoid potential race conditions
        let dataCopy = Data(data)
        
        // Safety check for empty data
        guard !dataCopy.isEmpty else {
            SecureLogger.log("Received empty version ack data from \(peerID)", category: SecureLogger.session, level: .error)
            return
        }
        
        // Try JSON first if it looks like JSON
        let ack: VersionAck?
        if let firstByte = dataCopy.first, firstByte == 0x7B { // '{' character
            ack = VersionAck.decode(from: dataCopy) ?? VersionAck.fromBinaryData(dataCopy)
        } else {
            ack = VersionAck.fromBinaryData(dataCopy) ?? VersionAck.decode(from: dataCopy)
        }
        
        guard let ack = ack else {
            SecureLogger.log("Failed to decode version ack from \(peerID)", category: SecureLogger.session, level: .error)
            return
        }
        
        if ack.rejected {
            SecureLogger.log("Version negotiation rejected by \(peerID): \(ack.reason ?? "Unknown reason")", 
                              category: SecureLogger.session, level: .error)
            versionNegotiationState[peerID] = .failed(reason: ack.reason ?? "Version rejected")
            
            // Clean up state for incompatible peer
            collectionsQueue.sync(flags: .barrier) {
                _ = self.activePeers.remove(peerID)
                _ = self.peerNicknames.removeValue(forKey: peerID)
                _ = self.lastHeardFromPeer.removeValue(forKey: peerID)
            }
            announcedPeers.remove(peerID)
            
            // Clean up any Noise session
            cleanupPeerCryptoState(peerID)
            
            // Notify delegate about incompatible peer disconnection
            DispatchQueue.main.async { [weak self] in
                self?.delegate?.didDisconnectFromPeer(peerID)
            }
        } else {
            SecureLogger.log("Version negotiation successful with \(peerID): agreed on v\(ack.agreedVersion) (server: \(ack.serverVersion), platform: \(ack.platform))", 
                              category: SecureLogger.session, level: .info)
            negotiatedVersions[peerID] = ack.agreedVersion
            versionNegotiationState[peerID] = .ackReceived(version: ack.agreedVersion)
            
            // If we were the initiator (sent hello first), proceed with Noise handshake
            // Note: Since we're handling their ACK, they initiated, so we should not initiate again
            // The peer who sent hello will initiate the Noise handshake
        }
    }
    
    private func sendVersionHello(to peripheral: CBPeripheral? = nil) {
        let hello = VersionHello(
            clientVersion: Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "1.0",
            platform: getPlatformString()
        )
        
        let helloData = hello.toBinaryData()
        
        let packet = BitchatPacket(
            type: MessageType.versionHello.rawValue,
            ttl: 1,  // Version negotiation is direct, no relay
            senderID: myPeerID,
            payload: helloData
        )
        
        // Mark that we initiated version negotiation
        // We don't know the peer ID yet from peripheral, so we'll track it when we get the response
        
        if let peripheral = peripheral,
           let characteristic = peripheralCharacteristics[peripheral] {
            // Send directly to specific peripheral
            if let data = packet.toBinaryData() {
                writeToPeripheral(data, peripheral: peripheral, characteristic: characteristic, peerID: nil)
            }
        } else {
            // Broadcast to all
            broadcastPacket(packet)
        }
    }
    
    private func sendVersionAck(_ ack: VersionAck, to peerID: String) {
        let ackData = ack.toBinaryData()
        
        let packet = BitchatPacket(
            type: MessageType.versionAck.rawValue,
            senderID: Data(myPeerID.utf8),
            recipientID: Data(peerID.utf8),
            timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
            payload: ackData,
            signature: nil,
            ttl: 1  // Direct response, no relay
        )
        
        broadcastPacket(packet)
    }
    
    private func getPlatformString() -> String {
        #if os(iOS)
        return "iOS"
        #elseif os(macOS)
        return "macOS"
        #else
        return "Unknown"
        #endif
    }
    
    // MARK: - Protocol ACK/NACK Handling
    
    private func handleProtocolAck(from peerID: String, data: Data) {
        guard let ack = ProtocolAck.fromBinaryData(data) else {
            SecureLogger.log("Failed to decode protocol ACK from \(peerID)", category: SecureLogger.session, level: .error)
            return
        }
        
        SecureLogger.log("Received protocol ACK from \(peerID) for packet \(ack.originalPacketID), type: \(ack.packetType)", 
                       category: SecureLogger.session, level: .debug)
        
        // Remove from pending ACKs
        _ = collectionsQueue.sync(flags: .barrier) {
            pendingAcks.removeValue(forKey: ack.originalPacketID)
        }
        
        // Handle specific packet types that need ACK confirmation
        if let messageType = MessageType(rawValue: ack.packetType) {
            switch messageType {
            case .noiseHandshakeInit, .noiseHandshakeResp:
                SecureLogger.log("Handshake packet \(ack.originalPacketID) confirmed by \(peerID)", 
                               category: SecureLogger.handshake, level: .info)
            case .noiseEncrypted:
                SecureLogger.log("Encrypted message \(ack.originalPacketID) confirmed by \(peerID)", 
                               category: SecureLogger.encryption, level: .debug)
            default:
                break
            }
        }
    }
    
    private func handleProtocolNack(from peerID: String, data: Data) {
        guard let nack = ProtocolNack.fromBinaryData(data) else {
            SecureLogger.log("Failed to decode protocol NACK from \(peerID)", category: SecureLogger.session, level: .error)
            return
        }
        
        SecureLogger.log("Received protocol NACK from \(peerID) for packet \(nack.originalPacketID): \(nack.reason)", 
                       category: SecureLogger.session, level: .warning)
        
        // Remove from pending ACKs
        _ = collectionsQueue.sync(flags: .barrier) {
            pendingAcks.removeValue(forKey: nack.originalPacketID)
        }
        
        // Handle specific error codes
        if let errorCode = ProtocolNack.ErrorCode(rawValue: nack.errorCode) {
            switch errorCode {
            case .decryptionFailed:
                // Session is out of sync - both sides need to clear and re-establish
                SecureLogger.log("Decryption failed at \(peerID), clearing session and re-establishing", 
                               category: SecureLogger.encryption, level: .warning)
                
                // Clear our session state and handshake coordinator state
                cleanupPeerCryptoState(peerID)
                handshakeCoordinator.resetHandshakeState(for: peerID)
                
                // Update connection state
                updatePeerConnectionState(peerID, state: .connected)
                
                // Use deterministic role assignment to prevent race conditions
                let shouldInitiate = handshakeCoordinator.determineHandshakeRole(
                    myPeerID: myPeerID,
                    remotePeerID: peerID
                ) == .initiator
                
                if shouldInitiate {
                    // Small delay to ensure both sides have cleared state
                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                        guard let self = self else { return }
                        SecureLogger.log("Initiating handshake after decryption failure with \(peerID)", 
                                       category: SecureLogger.session, level: .info)
                        self.attemptHandshakeIfNeeded(with: peerID, forceIfStale: true)
                    }
                } else {
                    // Send identity announcement to signal we're ready
                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                        guard let self = self else { return }
                        SecureLogger.log("Sending identity announcement after decryption failure to \(peerID)", 
                                       category: SecureLogger.session, level: .info)
                        self.sendNoiseIdentityAnnounce(to: peerID)
                    }
                }
            case .sessionExpired:
                // Clear session and re-handshake
                SecureLogger.log("Session expired at \(peerID), clearing and re-handshaking", 
                               category: SecureLogger.session, level: .warning)
                cleanupPeerCryptoState(peerID)
                handshakeCoordinator.resetHandshakeState(for: peerID)
                attemptHandshakeIfNeeded(with: peerID, forceIfStale: true)
            default:
                break
            }
        }
    }
    
    // Send protocol ACK for important packets
    private func sendProtocolAck(for packet: BitchatPacket, to peerID: String, hopCount: UInt8 = 0) {
        // Generate packet ID from packet content hash
        let packetID = generatePacketID(for: packet)
        
        let ack = ProtocolAck(
            originalPacketID: packetID,
            senderID: packet.senderID.hexEncodedString(),
            receiverID: myPeerID,
            packetType: packet.type,
            hopCount: hopCount
        )
        
        let ackPacket = BitchatPacket(
            type: MessageType.protocolAck.rawValue,
            senderID: Data(hexString: myPeerID) ?? Data(),
            recipientID: Data(hexString: peerID) ?? Data(),
            timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
            payload: ack.toBinaryData(),
            signature: nil,
            ttl: 3  // ACKs don't need to travel far
        )
        
        broadcastPacket(ackPacket)
    }
    
    // Send protocol NACK for failed packets
    private func sendProtocolNack(for packet: BitchatPacket, to peerID: String, reason: String, errorCode: ProtocolNack.ErrorCode) {
        let packetID = generatePacketID(for: packet)
        
        let nack = ProtocolNack(
            originalPacketID: packetID,
            senderID: packet.senderID.hexEncodedString(),
            receiverID: myPeerID,
            packetType: packet.type,
            reason: reason,
            errorCode: errorCode
        )
        
        let nackPacket = BitchatPacket(
            type: MessageType.protocolNack.rawValue,
            senderID: Data(hexString: myPeerID) ?? Data(),
            recipientID: Data(hexString: peerID) ?? Data(),
            timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
            payload: nack.toBinaryData(),
            signature: nil,
            ttl: 3  // NACKs don't need to travel far
        )
        
        broadcastPacket(nackPacket)
    }
    
    // Generate unique packet ID from packet content
    private func generatePacketID(for packet: BitchatPacket) -> String {
        // Use hash of packet data for unique ID
        if let data = packet.toBinaryData() {
            let hash = SHA256.hash(data: data)
            return hash.map { String(format: "%02x", $0) }.prefix(16).joined()
        }
        return UUID().uuidString
    }
    
    // Track packets that need ACKs
    private func trackPacketForAck(_ packet: BitchatPacket) {
        let packetID = generatePacketID(for: packet)
        
        collectionsQueue.sync(flags: .barrier) {
            pendingAcks[packetID] = (packet: packet, timestamp: Date(), retries: 0)
        }
        
        // Schedule timeout check
        DispatchQueue.main.asyncAfter(deadline: .now() + ackTimeout) { [weak self] in
            self?.checkAckTimeout(for: packetID)
        }
    }
    
    // Check for ACK timeout and retry if needed
    private func checkAckTimeout(for packetID: String) {
        collectionsQueue.sync(flags: .barrier) { [weak self] in
            guard let self = self,
                  let pending = self.pendingAcks[packetID] else { return }
            
            if pending.retries < self.maxAckRetries {
                // Retry sending the packet
                SecureLogger.log("ACK timeout for packet \(packetID), retrying (attempt \(pending.retries + 1))", 
                               category: SecureLogger.session, level: .warning)
                
                self.pendingAcks[packetID] = (packet: pending.packet, 
                                              timestamp: Date(), 
                                              retries: pending.retries + 1)
                
                // Resend the packet
                DispatchQueue.main.async {
                    self.broadcastPacket(pending.packet)
                }
                
                // Schedule next timeout check
                DispatchQueue.main.asyncAfter(deadline: .now() + self.ackTimeout) {
                    self.checkAckTimeout(for: packetID)
                }
            } else {
                // Max retries reached, give up
                SecureLogger.log("Max ACK retries reached for packet \(packetID), giving up", 
                               category: SecureLogger.session, level: .error)
                self.pendingAcks.removeValue(forKey: packetID)
                
                // Could notify upper layer about delivery failure here
            }
        }
    }
    
    // Check all pending ACKs for timeouts (called by timer)
    private func checkAckTimeouts() {
        let now = Date()
        var timedOutPackets: [String] = []
        
        collectionsQueue.sync {
            for (packetID, pending) in pendingAcks {
                if now.timeIntervalSince(pending.timestamp) > ackTimeout {
                    timedOutPackets.append(packetID)
                }
            }
        }
        
        // Process timeouts outside the sync block
        for packetID in timedOutPackets {
            checkAckTimeout(for: packetID)
        }
    }
    
    // Check peer availability based on last heard time
    private func checkPeerAvailability() {
        let now = Date()
        var stateChanges: [(peerID: String, available: Bool)] = []
        
        collectionsQueue.sync(flags: .barrier) {
            // Check all active peers
            for peerID in activePeers {
                let lastHeard = lastHeardFromPeer[peerID] ?? Date.distantPast
                let timeSinceLastHeard = now.timeIntervalSince(lastHeard)
                let wasAvailable = peerAvailabilityState[peerID] ?? true
                
                // Check connection state
                let connectionState = peerConnectionStates[peerID] ?? .disconnected
                let hasConnection = connectionState == .connected || connectionState == .authenticating || connectionState == .authenticated
                
                // Peer is available if:
                // 1. We have an active connection AND heard from them recently, OR
                // 2. We're authenticated and heard from them within timeout period
                let isAvailable = (hasConnection && timeSinceLastHeard < 60.0) || 
                                (connectionState == .authenticated && timeSinceLastHeard < peerAvailabilityTimeout)
                
                if wasAvailable != isAvailable {
                    peerAvailabilityState[peerID] = isAvailable
                    stateChanges.append((peerID: peerID, available: isAvailable))
                }
            }
            
            // Remove availability state for peers no longer active
            let inactivePeers = peerAvailabilityState.keys.filter { !activePeers.contains($0) }
            for peerID in inactivePeers {
                peerAvailabilityState.removeValue(forKey: peerID)
            }
        }
        
        // Notify about availability changes
        for change in stateChanges {
            SecureLogger.log("Peer \(change.peerID) availability changed to: \(change.available)", 
                           category: SecureLogger.session, level: .info)
            
            // Notify delegate about availability change
            DispatchQueue.main.async { [weak self] in
                self?.delegate?.peerAvailabilityChanged(change.peerID, available: change.available)
            }
        }
    }
    
    // Update peer availability when we hear from them
    private func updatePeerAvailability(_ peerID: String) {
        collectionsQueue.sync(flags: .barrier) {
            lastHeardFromPeer[peerID] = Date()
            
            // If peer wasn't available, mark as available now
            if peerAvailabilityState[peerID] != true {
                peerAvailabilityState[peerID] = true
                
                SecureLogger.log("Peer \(peerID) marked as available after hearing from them", 
                               category: SecureLogger.session, level: .info)
                
                DispatchQueue.main.async { [weak self] in
                    self?.delegate?.peerAvailabilityChanged(peerID, available: true)
                }
            }
        }
    }
    
    // Check if a peer is currently available
    func isPeerAvailable(_ peerID: String) -> Bool {
        return collectionsQueue.sync {
            return peerAvailabilityState[peerID] ?? false
        }
    }
    
    private func sendNoiseIdentityAnnounce(to specificPeerID: String? = nil) {
        // Rate limit identity announcements
        let now = Date()
        
        // If targeting a specific peer, check rate limit
        if let peerID = specificPeerID {
            if let lastTime = lastIdentityAnnounceTimes[peerID],
               now.timeIntervalSince(lastTime) < identityAnnounceMinInterval {
                // Too soon, skip this announcement
                return
            }
            lastIdentityAnnounceTimes[peerID] = now
        } else {
            // Broadcasting to all - check global rate limit
            if let lastTime = lastIdentityAnnounceTimes["*broadcast*"],
               now.timeIntervalSince(lastTime) < identityAnnounceMinInterval {
                return
            }
            lastIdentityAnnounceTimes["*broadcast*"] = now
        }
        
        // Get our Noise static public key and signing public key
        let staticKey = noiseService.getStaticPublicKeyData()
        let signingKey = noiseService.getSigningPublicKeyData()
        
        // Get nickname from delegate
        let nickname = (delegate as? ChatViewModel)?.nickname ?? "Anonymous"
        
        // Create the binding data to sign (peerID + publicKey + timestamp)
        let timestampData = String(Int64(now.timeIntervalSince1970 * 1000)).data(using: .utf8)!
        let bindingData = myPeerID.data(using: .utf8)! + staticKey + timestampData
        
        // Sign the binding with our Ed25519 signing key
        let signature = noiseService.signData(bindingData) ?? Data()
        
        // Create the identity announcement
        let announcement = NoiseIdentityAnnouncement(
            peerID: myPeerID,
            publicKey: staticKey,
            signingPublicKey: signingKey,
            nickname: nickname,
            timestamp: now,
            previousPeerID: previousPeerID,
            signature: signature
        )
        
        // Encode the announcement
        let announcementData = announcement.toBinaryData()
        
        let packet = BitchatPacket(
            type: MessageType.noiseIdentityAnnounce.rawValue,
            senderID: Data(hexString: myPeerID) ?? Data(),
            recipientID: specificPeerID.flatMap { Data(hexString: $0) },  // Targeted or broadcast
            timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
            payload: announcementData,
            signature: nil,
            ttl: adaptiveTTL
        )
        
        if let targetPeer = specificPeerID {
            SecureLogger.log("Sending targeted identity announce to \(targetPeer)", 
                           category: SecureLogger.noise, level: .info)
        } else {
            SecureLogger.log("Broadcasting identity announce to all peers", 
                           category: SecureLogger.noise, level: .info)
        }
        
        broadcastPacket(packet)
    }
    
    // Removed sendPacket method - all packets should use broadcastPacket to ensure mesh delivery
    
    // Send private message using Noise Protocol
    private func sendPrivateMessageViaNoise(_ content: String, to recipientPeerID: String, recipientNickname: String, messageID: String? = nil) {
        // Use per-peer encryption queue to prevent nonce desynchronization
        let encryptionQueue = getEncryptionQueue(for: recipientPeerID)
        
        encryptionQueue.async { [weak self] in
            guard let self = self else { return }
            
            // Use noiseService directly
            
            // Check if we have a Noise session with this peer
            let hasSession = self.noiseService.hasEstablishedSession(with: recipientPeerID)
            
            // Check if session is stale (no successful communication for a while)
            var sessionIsStale = false
            if hasSession {
            let lastSuccess = lastSuccessfulMessageTime[recipientPeerID] ?? Date.distantPast
            let sessionAge = Date().timeIntervalSince(lastSuccess)
            // Increase session validity to 24 hours - sessions should persist across temporary disconnects
            if sessionAge > 86400.0 { // More than 24 hours since last successful message
                sessionIsStale = true
                SecureLogger.log("Session with \(recipientPeerID) is stale (last success: \(Int(sessionAge))s ago), will re-establish", category: SecureLogger.noise, level: .info)
            }
        }
        
        if !hasSession || sessionIsStale {
            if sessionIsStale {
                // Clear stale session first
                cleanupPeerCryptoState(recipientPeerID)
            }
            SecureLogger.log("No valid Noise session with \(recipientPeerID), initiating handshake", category: SecureLogger.noise, level: .info)
            
            // Apply tie-breaker logic for handshake initiation
            if myPeerID < recipientPeerID {
                // We have lower ID, initiate handshake
                initiateNoiseHandshake(with: recipientPeerID)
            } else {
                // We have higher ID, send targeted identity announce to prompt them to initiate
                sendNoiseIdentityAnnounce(to: recipientPeerID)
            }
            
            // Queue message for sending after handshake completes
            messageQueue.async(flags: .barrier) { [weak self] in
                guard let self = self else { return }
                if self.pendingPrivateMessages[recipientPeerID] == nil {
                    self.pendingPrivateMessages[recipientPeerID] = []
                }
                self.pendingPrivateMessages[recipientPeerID]?.append((content, recipientNickname, messageID ?? UUID().uuidString))
                let count = self.pendingPrivateMessages[recipientPeerID]?.count ?? 0
                SecureLogger.log("Queued private message for \(recipientPeerID), \(count) messages pending", category: SecureLogger.noise, level: .info)
            }
            return
        }
        
        // Use provided message ID or generate a new one
        let msgID = messageID ?? UUID().uuidString
        
        // Check if we're already processing this message
        let sendKey = "\(msgID)-\(recipientPeerID)"
        let alreadySending = self.collectionsQueue.sync(flags: .barrier) {
            if self.recentlySentMessages.contains(sendKey) {
                return true
            }
            self.recentlySentMessages.insert(sendKey)
            // Clean up old entries after 10 seconds
            DispatchQueue.main.asyncAfter(deadline: .now() + 10.0) { [weak self] in
                self?.collectionsQueue.sync(flags: .barrier) {
                    _ = self?.recentlySentMessages.remove(sendKey)
                }
            }
            return false
        }
        
        if alreadySending {
            return
        }
        
        
        // Get sender nickname from delegate
        let nickname = self.delegate as? ChatViewModel
        let senderNick = nickname?.nickname ?? self.myPeerID
        
        // Create the inner message
        let message = BitchatMessage(
            id: msgID,
            sender: senderNick,
            content: content,
            timestamp: Date(),
            isRelay: false,
            isPrivate: true,
            recipientNickname: recipientNickname,
            senderPeerID: myPeerID
        )
        
        // Use binary payload format to match the receiver's expectations
        guard let messageData = message.toBinaryPayload() else { 
            return 
        }
        
        // Create inner packet
        let innerPacket = BitchatPacket(
            type: MessageType.message.rawValue,
            senderID: Data(hexString: myPeerID) ?? Data(),
            recipientID: Data(hexString: recipientPeerID) ?? Data(),
            timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
            payload: messageData,
            signature: nil,
            ttl: self.adaptiveTTL // Inner packet needs valid TTL for processing after decryption
        )
        
        guard let innerData = innerPacket.toBinaryData() else { return }
        
        do {
            // Encrypt with Noise
            SecureLogger.log("Encrypting private message \(msgID) for \(recipientPeerID)", category: SecureLogger.encryption, level: .debug)
            let encryptedData = try noiseService.encrypt(innerData, for: recipientPeerID)
            SecureLogger.log("Successfully encrypted message, size: \(encryptedData.count)", category: SecureLogger.encryption, level: .debug)
            
            // Update last successful message time
            lastSuccessfulMessageTime[recipientPeerID] = Date()
            
            // Send as Noise encrypted message
            let outerPacket = BitchatPacket(
                type: MessageType.noiseEncrypted.rawValue,
                senderID: Data(hexString: myPeerID) ?? Data(),
                recipientID: Data(hexString: recipientPeerID) ?? Data(),
                timestamp: UInt64(Date().timeIntervalSince1970 * 1000),
                payload: encryptedData,
                signature: nil,
                ttl: adaptiveTTL
            )
            
            SecureLogger.log("Broadcasting encrypted private message \(msgID) to \(recipientPeerID)", category: SecureLogger.session, level: .info)
            
            // Track packet for ACK
            trackPacketForAck(outerPacket)
            
            broadcastPacket(outerPacket)
        } catch {
            // Failed to encrypt message
            SecureLogger.log("Failed to encrypt private message \(msgID) for \(recipientPeerID): \(error)", category: SecureLogger.encryption, level: .error)
        }
        } // End of encryptionQueue.async
    }
    
    // MARK: - Connection Pool Management
    
    private func findLeastRecentlyUsedPeripheral() -> String? {
        var lruPeripheralID: String?
        var oldestActivityTime = Date()
        
        for (peripheralID, peripheral) in connectionPool {
            // Only consider connected peripherals
            guard peripheral.state == .connected else { continue }
            
            // Skip if this peripheral has an active peer connection
            if let peerID = peerIDByPeripheralID[peripheralID],
               activePeers.contains(peerID) {
                continue
            }
            
            // Find the least recently used peripheral based on last activity
            if let lastActivity = lastActivityByPeripheralID[peripheralID],
               lastActivity < oldestActivityTime {
                oldestActivityTime = lastActivity
                lruPeripheralID = peripheralID
            } else if lastActivityByPeripheralID[peripheralID] == nil {
                // If no activity recorded, it's a candidate for removal
                lruPeripheralID = peripheralID
                break
            }
        }
        
        return lruPeripheralID
    }
    
    // Track activity for peripherals
    private func updatePeripheralActivity(_ peripheralID: String) {
        lastActivityByPeripheralID[peripheralID] = Date()
    }
}