import UIKit
import Flutter
import AVFoundation

@main
@objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate {
  private var iosAudioLifecycleChannel: FlutterMethodChannel?
  private var iosPlatformChannel: FlutterMethodChannel?
  private var iosAudioSessionChannel: FlutterMethodChannel?

  /// Tracks whether a voice channel is currently active.
  ///
  /// The AVAudioSession is intentionally not configured for VoIP at
  /// app launch — that would interrupt other apps' audio (Spotify,
  /// Apple Music, podcasts) the moment the user opens Chanora, even
  /// when they're just reading chat. Production VoIP apps (Telegram
  /// group calls, Signal, Discord, Element) only switch the session
  /// to `.playAndRecord` + `.voiceChat` when the user actually joins
  /// a voice channel. See `docs/architecture/sad.md` and the
  /// `chanora/ios_audio_session` MethodChannel contract.
  ///
  /// This flag gates lifecycle handlers (interruption-ended,
  /// media-services-reset) so we only rebuild the VoIP session if a
  /// call is actually in progress. When false, those handlers leave
  /// the session in the inactive `.ambient` baseline.
  private var voiceSessionActive: Bool = false

  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    DispatchQueue.global(qos: .utility).async {
      ChanoraSileroSelfTest.run()
    }

    // AVAudioSession lifecycle policy (DEC-2026-06-08, supersedes
    // the launch-time .playAndRecord setup):
    //
    // At launch we set the category to .ambient and leave the
    // session INACTIVE — matching the Telegram / Signal / Discord /
    // Element / Jitsi pattern and Apple's guidance that "a VoIP
    // app's audio session should not be active" while idle.
    // Configuring .playAndRecord + .voiceChat at launch stops other
    // apps' music (Spotify, Apple Music, podcasts) the moment the
    // user opens Chanora, even when they are just reading text chat.
    //
    // VoIP configuration is engaged on voice-channel join via the
    // `chanora/ios_audio_session` MethodChannel, driven from Dart
    // before `voiceJoin` starts VoiceProcessingIO and again as an
    // idempotent guard on the AudioStarted lifecycle.
    do {
      try AVAudioSession.sharedInstance().setCategory(.ambient, mode: .default)
      logAudioSessionState(context: "launch-ambient")
    } catch {
      NSLog("chanora_flutter: AVAudioSession .ambient baseline failed: \(error)")
    }

    NotificationCenter.default.addObserver(
      self,
      selector: #selector(handleRouteChange(_:)),
      name: AVAudioSession.routeChangeNotification,
      object: nil
    )

    NotificationCenter.default.addObserver(
      self,
      selector: #selector(handleInterruption(_:)),
      name: AVAudioSession.interruptionNotification,
      object: nil
    )

    NotificationCenter.default.addObserver(
      self,
      selector: #selector(handleMediaServicesReset(_:)),
      name: AVAudioSession.mediaServicesWereResetNotification,
      object: nil
    )

    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

  /// Activate the VoIP audio session. Called from Dart via the
  /// `chanora/ios_audio_session` channel before a voice channel join
  /// starts VoiceProcessingIO. Configures
  /// .playAndRecord + .voiceChat with .mixWithOthers so other apps
  /// (Spotify, podcasts) can keep playing alongside the voice
  /// channel — matching the Telegram group-call UX. Idempotent:
  /// repeated calls while already active are a no-op.
  private func activateVoiceSession() {
    do {
      let session = AVAudioSession.sharedInstance()
      try session.setCategory(
        .playAndRecord,
        mode: .voiceChat,
        options: [.defaultToSpeaker, .allowBluetoothHFP, .allowBluetoothA2DP, .mixWithOthers]
      )
      try session.setPreferredIOBufferDuration(0.02)
      try session.setPreferredSampleRate(48000.0)
      try session.setActive(true, options: [])
      voiceSessionActive = true
      logAudioSessionState(context: "activateVoiceSession")
      let ins = session.currentRoute.inputs.map { $0.portType.rawValue }.joined(separator: ",")
      NSLog(
        "chanora_flutter: voice session active: " +
        "sampleRate=\(session.sampleRate) " +
        "ioBufferDuration=\(String(format: "%.4f", session.ioBufferDuration)) " +
        "inputs=[\(ins)] outputVolume=\(session.outputVolume)"
      )
    } catch {
      NSLog("chanora_flutter: activateVoiceSession failed: \(error)")
    }
  }

  /// Deactivate the VoIP audio session and return to the idle
  /// .ambient baseline. Called from Dart on `BridgeEvent::AudioStopped`
  /// (intentional leave, disconnect, or connection lost).
  /// `.notifyOthersOnDeactivation` lets other audio apps know they
  /// can resume — best-effort: Apple Music / Podcasts resume
  /// reliably, Spotify is not guaranteed.
  private func deactivateVoiceSession() {
    let session = AVAudioSession.sharedInstance()
    do {
      try session.setActive(false, options: [.notifyOthersOnDeactivation])
    } catch {
      NSLog("chanora_flutter: deactivateVoiceSession setActive(false) failed: \(error)")
    }
    do {
      try session.setCategory(.ambient, mode: .default)
    } catch {
      NSLog("chanora_flutter: deactivateVoiceSession setCategory(.ambient) failed: \(error)")
    }
    voiceSessionActive = false
    logAudioSessionState(context: "deactivateVoiceSession")
  }

  /// Reads back the actual AVAudioSession state and logs it for
  /// SDD-098 compliance. Called after both setCategory and setActive
  /// to verify that the session accepted the requested configuration.
  private func logAudioSessionState(context: String) {
    let s = AVAudioSession.sharedInstance()
    NSLog("chanora_flutter: [\(context)] category=\(s.category.rawValue) mode=\(s.mode.rawValue) options=\(s.categoryOptions.rawValue) route outputs=\(s.currentRoute.outputs.map { "\($0.portType.rawValue)" })")
    if s.sampleRate != 48000.0 {
      NSLog("chanora_flutter: WARNING: actual sample rate \(s.sampleRate) != requested 48000")
    }
    if s.ioBufferDuration > 0.025 {
      NSLog("chanora_flutter: WARNING: IO buffer duration \(s.ioBufferDuration) > 25ms, may cause latency")
    }
  }

  @objc private func handleRouteChange(_ notification: Notification) {
    guard let userInfo = notification.userInfo,
          let reasonValue = userInfo[AVAudioSessionRouteChangeReasonKey] as? UInt,
          let reason = AVAudioSession.RouteChangeReason(rawValue: reasonValue)
    else {
      return
    }

    let routeDescription = AVAudioSession.sharedInstance().currentRoute
    let outputs = routeDescription.outputs.map { $0.portType.rawValue }.joined(separator: ",")
    NSLog("chanora_flutter: route change reason=\(reason.rawValue) outputs=\(outputs)")

    // P1: Send the detailed route class to Rust on every route change,
    // not just device plug/unplug. This covers:
    //   - .newDeviceAvailable / .oldDeviceUnavailable (headset plug/unplug)
    //   - .override (speaker/earpiece toggle)
    //   - .categoryChange (session category changed)
    //   - .wakeFromSleep (device woke from sleep)
    //   - .routeConfigurationChange (BT HFP connect/disconnect)
    // The Rust side uses the route class to recompute the processing
    // policy (route_policy.rs) and reset AEC delay state if needed.
    let routeClass = classifyAudioRoute(routeDescription)
    NSLog("chanora_flutter: route class=\(routeClass) reason=\(reason.rawValue)")
    iosAudioLifecycleChannel?.invokeMethod("handleRouteChange", arguments: routeClass)
  }

  @objc private func handleInterruption(_ notification: Notification) {
    guard let userInfo = notification.userInfo,
          let typeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
          let type = AVAudioSession.InterruptionType(rawValue: typeValue)
    else {
      return
    }

    switch type {
    case .began:
      NSLog("chanora_flutter: audio interruption began")
      iosAudioLifecycleChannel?.invokeMethod("handleInterruptionBegan", arguments: nil)
    case .ended:
      let shouldResume = (userInfo[AVAudioSessionInterruptionOptionKey] as? UInt)
        .map { $0 & AVAudioSession.InterruptionOptions.shouldResume.rawValue != 0 }
        ?? false
      NSLog("chanora_flutter: audio interruption ended shouldResume=\(shouldResume)")
      iosAudioLifecycleChannel?.invokeMethod("handleInterruptionEnded", arguments: shouldResume)
    @unknown default:
      break
    }
  }

  @objc private func handleMediaServicesReset(_ notification: Notification) {
    NSLog("chanora_flutter: media services reset voiceActive=\(voiceSessionActive)")
    if voiceSessionActive {
      do {
        let session = AVAudioSession.sharedInstance()
        try session.setCategory(
          .playAndRecord,
          mode: .voiceChat,
          options: [.defaultToSpeaker, .allowBluetoothHFP, .allowBluetoothA2DP, .mixWithOthers]
        )
        try session.setPreferredIOBufferDuration(0.02)
        try session.setPreferredSampleRate(48000.0)
        try session.setActive(true, options: [])
        logAudioSessionState(context: "mediaServicesWereReset-voip")
      } catch {
        NSLog("chanora_flutter: AVAudioSession media-services reset rebuild failed: \(error)")
      }
    } else {
      do {
        try AVAudioSession.sharedInstance().setCategory(.ambient, mode: .default)
        logAudioSessionState(context: "mediaServicesWereReset-ambient")
      } catch {
        NSLog("chanora_flutter: AVAudioSession media-services reset ambient restore failed: \(error)")
      }
    }
    let routeClass = classifyAudioRoute(AVAudioSession.sharedInstance().currentRoute)
    NSLog("chanora_flutter: media services reset complete, route=\(routeClass)")
    iosAudioLifecycleChannel?.invokeMethod("handleMediaServicesReset", arguments: routeClass)
  }

  override func applicationWillResignActive(_ application: UIApplication) {
    iosAudioLifecycleChannel?.invokeMethod("handleWillResignActive", arguments: nil)
  }

  override func applicationDidEnterBackground(_ application: UIApplication) {
    iosAudioLifecycleChannel?.invokeMethod("handleDidEnterBackground", arguments: nil)
  }

  override func applicationWillEnterForeground(_ application: UIApplication) {
    iosAudioLifecycleChannel?.invokeMethod("handleWillEnterForeground", arguments: nil)
  }

  override func applicationWillTerminate(_ application: UIApplication) {
    iosAudioLifecycleChannel?.invokeMethod("handleWillTerminate", arguments: nil)
  }

  func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
    GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
    iosAudioLifecycleChannel = FlutterMethodChannel(
      name: "chanora/ios_audio_lifecycle",
      binaryMessenger: engineBridge.applicationRegistrar.messenger()
    )
    iosPlatformChannel = FlutterMethodChannel(
      name: "chanora/ios_platform",
      binaryMessenger: engineBridge.applicationRegistrar.messenger()
    )
    iosAudioSessionChannel = FlutterMethodChannel(
      name: "chanora/ios_audio_session",
      binaryMessenger: engineBridge.applicationRegistrar.messenger()
    )
    iosAudioSessionChannel?.setMethodCallHandler { [weak self] call, result in
      guard let self = self else {
        result(FlutterError(code: "delegate_gone", message: "AppDelegate deallocated", details: nil))
        return
      }
      switch call.method {
      case "activateVoiceSession":
        self.activateVoiceSession()
        result(nil)
      case "deactivateVoiceSession":
        self.deactivateVoiceSession()
        result(nil)
      default:
        result(FlutterMethodNotImplemented)
      }
    }
    iosPlatformChannel?.setMethodCallHandler { call, result in
      switch call.method {
      case "getMicrophonePermissionState":
        result(self.microphonePermissionStateString())
      case "requestMicrophonePermission":
        AVAudioSession.sharedInstance().requestRecordPermission { granted in
          DispatchQueue.main.async {
            result(granted ? "Granted" : self.microphonePermissionStateString())
          }
        }
      case "openAppSettings":
        guard let url = URL(string: UIApplication.openSettingsURLString) else {
          result(false)
          return
        }
        UIApplication.shared.open(url, options: [:]) { opened in
          result(opened)
        }
      default:
        result(FlutterMethodNotImplemented)
      }
    }
  }

  private func classifyAudioRoute(_ route: AVAudioSessionRouteDescription) -> String {
    for output in route.outputs {
      switch output.portType {
      case .builtInReceiver:
        return "Earpiece"
      case .builtInSpeaker:
        return "Speaker"
      case .headphones, .usbAudio:
        return "WiredHeadset"
      case .bluetoothHFP:
        return "BluetoothHfp"
      case .bluetoothA2DP:
        return "BluetoothA2dp"
      default:
        break
      }
    }
    return "Unknown"
  }

  private func microphonePermissionStateString() -> String {
    switch AVAudioSession.sharedInstance().recordPermission {
    case .granted:
      return "Granted"
    case .denied:
      return "Denied"
    case .undetermined:
      return "NotDetermined"
    @unknown default:
      return "Unknown"
    }
  }

  deinit {
    NotificationCenter.default.removeObserver(self)
  }
}