Add nickname validation to prevent empty names

- Validate nickname only when field loses focus or on submit
- Replace empty nicknames with anon+random 4 digits (e.g. anon3847)
- Remove auto-save timer to prevent validation while typing
- Add FocusState to detect when user exits the field

bitchat/ViewModels/ChatViewModel.swift

@@ -18,14 +18,7 @@ import UIKit
 class ChatViewModel: ObservableObject {
     @Published var messages: [BitchatMessage] = []
     @Published var connectedPeers: [String] = []
-    @Published var nickname: String = "" {
-        didSet {
-            nicknameSaveTimer?.invalidate()
-            nicknameSaveTimer = Timer.scheduledTimer(withTimeInterval: 0.5, repeats: false) { _ in
-                self.saveNickname()
-            }
-        }
-    }
+    @Published var nickname: String = ""
     @Published var isConnected = false
     @Published var privateChats: [String: [BitchatMessage]] = [:] // peerID -> messages
     @Published var selectedPrivateChatPeer: String? = nil
@@ -42,7 +35,6 @@ class ChatViewModel: ObservableObject {
     var meshService = BluetoothMeshService()
     private let userDefaults = UserDefaults.standard
     private let nicknameKey = "bitchat.nickname"
-    private var nicknameSaveTimer: Timer?
     
     @Published var favoritePeers: Set<String> = []  // Now stores public key fingerprints instead of peer IDs
     private var peerIDToPublicKeyFingerprint: [String: String] = [:]  // Maps ephemeral peer IDs to persistent fingerprints
@@ -172,6 +164,14 @@ class ChatViewModel: ObservableObject {
         meshService.sendBroadcastAnnounce()
     }
     
+    func validateAndSaveNickname() {
+        // Check if nickname is empty or just whitespace
+        if nickname.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
+            nickname = "anon\(Int.random(in: 1000...9999))"
+        }
+        saveNickname()
+    }
+    
     private func loadFavorites() {
         // Load favorites from secure storage
         favoritePeers = SecureIdentityStateManager.shared.getFavorites()