bitchat/bitchatTests/ChatMediaPreparationTests.swift

import BitFoundation
import CoreGraphics
import Foundation
import ImageIO
import Testing
import UniformTypeIdentifiers
#if os(iOS)
import UIKit
#else
import AppKit
#endif
@testable import bitchat

struct ChatMediaPreparationTests {
    @Test
    func prepareVoiceNotePacket_buildsEncodedAudioPacket() throws {
        let url = FileManager.default.temporaryDirectory.appendingPathComponent("voice-\(UUID().uuidString).m4a")
        try Data("voice".utf8).write(to: url, options: .atomic)
        defer { try? FileManager.default.removeItem(at: url) }

        let packet = try ChatMediaPreparation.prepareVoiceNotePacket(at: url)

        #expect(packet.fileName == url.lastPathComponent)
        #expect(packet.mimeType == "audio/mp4")
        #expect(packet.fileSize == 5)
        #expect(packet.encode() != nil)
    }

    @Test
    func prepareVoiceNotePacket_rejectsOversizedAudio() throws {
        let url = FileManager.default.temporaryDirectory.appendingPathComponent("voice-too-large-\(UUID().uuidString).m4a")
        try Data(repeating: 0x55, count: FileTransferLimits.maxVoiceNoteBytes + 1).write(to: url, options: .atomic)
        defer { try? FileManager.default.removeItem(at: url) }

        #expect(throws: ChatMediaPreparationError.voiceNoteTooLarge(bytes: FileTransferLimits.maxVoiceNoteBytes + 1)) {
            try ChatMediaPreparation.prepareVoiceNotePacket(at: url)
        }
    }

    @Test
    func prepareImagePacket_rejectsInvalidImage() throws {
        let url = FileManager.default.temporaryDirectory.appendingPathComponent("invalid-\(UUID().uuidString).jpg")
        try Data("not-an-image".utf8).write(to: url, options: .atomic)
        defer { try? FileManager.default.removeItem(at: url) }

        #expect(throws: ImageUtilsError.invalidImage) {
            try ChatMediaPreparation.prepareImagePacket(from: url)
        }
    }

    @Test
    func prepareImagePacket_buildsEncodedJpegPacket() throws {
        let sourceURL = try makeTemporaryImageURL()
        defer { try? FileManager.default.removeItem(at: sourceURL) }

        let prepared = try ChatMediaPreparation.prepareImagePacket(from: sourceURL)
        defer { try? FileManager.default.removeItem(at: prepared.outputURL) }

        #expect(prepared.packet.fileName == prepared.outputURL.lastPathComponent)
        #expect(prepared.packet.mimeType == "image/jpeg")
        #expect(prepared.packet.fileSize == UInt64(prepared.packet.content.count))
        #expect(prepared.packet.encode() != nil)
    }

    /// A genuinely detailed photo must prepare to more than
    /// `TransportConfig.wifiBulkMinPayloadBytes` (64 KiB); otherwise the Wi-Fi
    /// bulk (AWDL) data plane is never offered in production because
    /// `WifiBulkPolicy.shouldOffer` requires `payloadBytes > 64 KiB`.
    /// Regression guard for the ~40 KB over-compression gap (PR #1385).
    @Test
    func prepareImagePacket_detailedImageExceedsWifiBulkThreshold() throws {
        let sourceURL = try makeDetailedImageURL(dimension: 1200)
        defer { try? FileManager.default.removeItem(at: sourceURL) }

        let prepared = try ChatMediaPreparation.prepareImagePacket(from: sourceURL)
        defer { try? FileManager.default.removeItem(at: prepared.outputURL) }

        // Comfortably above the 64 KiB Wi-Fi bulk offer threshold...
        #expect(prepared.packet.content.count > TransportConfig.wifiBulkMinPayloadBytes)
        // ...and still within the hard image cap for the BLE path.
        #expect(prepared.packet.content.count <= FileTransferLimits.maxImageBytes)
    }
}

private func makeTemporaryImageURL() throws -> URL {
    let url = FileManager.default.temporaryDirectory.appendingPathComponent("image-\(UUID().uuidString).png")
    #if os(iOS)
    let renderer = UIGraphicsImageRenderer(size: CGSize(width: 64, height: 64))
    let image = renderer.image { context in
        UIColor.systemTeal.setFill()
        context.fill(CGRect(x: 0, y: 0, width: 64, height: 64))
    }
    guard let data = image.pngData() else {
        throw ChatMediaPreparationTestError.imageEncodingFailed
    }
    #else
    let image = NSImage(size: NSSize(width: 64, height: 64))
    image.lockFocus()
    NSColor.systemTeal.setFill()
    NSRect(x: 0, y: 0, width: 64, height: 64).fill()
    image.unlockFocus()
    guard let tiff = image.tiffRepresentation,
          let bitmap = NSBitmapImageRep(data: tiff),
          let data = bitmap.representation(using: .png, properties: [:]) else {
        throw ChatMediaPreparationTestError.imageEncodingFailed
    }
    #endif
    try data.write(to: url, options: .atomic)
    return url
}

/// Builds a random-noise PNG. Noise is incompressible, so the JPEG the prep
/// pipeline produces stays large — a faithful stand-in for a detailed photo,
/// unlike a flat solid-color image which would compress to a few KB regardless
/// of dimension.
private func makeDetailedImageURL(dimension: Int) throws -> URL {
    let width = dimension
    let height = dimension
    let bytesPerPixel = 4
    let bytesPerRow = width * bytesPerPixel

    var pixels = [UInt8](repeating: 0, count: bytesPerRow * height)
    for index in pixels.indices {
        pixels[index] = UInt8.random(in: 0...255)
    }

    let colorSpace = CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB()
    guard let context = CGContext(
        data: &pixels,
        width: width,
        height: height,
        bitsPerComponent: 8,
        bytesPerRow: bytesPerRow,
        space: colorSpace,
        bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
    ), let cgImage = context.makeImage() else {
        throw ChatMediaPreparationTestError.imageEncodingFailed
    }

    let url = FileManager.default.temporaryDirectory.appendingPathComponent("detailed-\(UUID().uuidString).png")
    guard let destination = CGImageDestinationCreateWithURL(
        url as CFURL,
        UTType.png.identifier as CFString,
        1,
        nil
    ) else {
        throw ChatMediaPreparationTestError.imageEncodingFailed
    }
    CGImageDestinationAddImage(destination, cgImage, nil)
    guard CGImageDestinationFinalize(destination) else {
        throw ChatMediaPreparationTestError.imageEncodingFailed
    }
    return url
}

private enum ChatMediaPreparationTestError: Error {
    case imageEncodingFailed
}