import UIKit
import Flutter
import Firebase
import PushKit
import CallKit
import AVFAudio
import flutter_callkit_incoming

@main
@objc class AppDelegate: FlutterAppDelegate, PKPushRegistryDelegate, CallkitIncomingAppDelegate {

  // Expose the Flutter engine for SceneDelegate to use
  lazy var flutterEngine = FlutterEngine(name: "my flutter engine")

  // Must be retained for the lifetime of the app, otherwise VoIP pushes stop.
  private var voipRegistry: PKPushRegistry?

  // Keeps the app alive briefly after a decline so Dart can notify the caller.
  private var declineTask: UIBackgroundTaskIdentifier = .invalid

  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    // Initialize Firebase
    FirebaseApp.configure()

    // Start running the Flutter engine
    flutterEngine.run()

    // Register plugins with the engine
    GeneratedPluginRegistrant.register(with: self.flutterEngine)


    // Register for VoIP pushes AFTER plugins, so flutter_callkit_incoming is ready.
    let registry = PKPushRegistry(queue: .main)
    registry.delegate = self
    registry.desiredPushTypes = [.voIP]
    voipRegistry = registry

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

  // UIScene lifecycle support
  override func application(
    _ application: UIApplication,
    configurationForConnecting connectingSceneSession: UISceneSession,
    options: UIScene.ConnectionOptions
  ) -> UISceneConfiguration {
    let sceneConfiguration = UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    sceneConfiguration.delegateClass = SceneDelegate.self
    return sceneConfiguration
  }

  // MARK: - CallkitIncomingAppDelegate
  // The plugin hands these actions to the app delegate; every one must be fulfilled
  // (that is what the plugin does itself when the delegate does not conform).

  func onAccept(_ call: Call, _ action: CXAnswerCallAction) {
    action.fulfill()
  }

  func onDecline(_ call: Call, _ action: CXEndCallAction) {
    action.fulfill()
    // App launched in the background by a VoIP push (killed state): once the call is declined
    // iOS may suspend the app almost immediately. Keep it alive briefly so the Dart decline
    // handler (CallKitEvents in firebase_notification_manger.dart) can notify the caller.
    beginDeclineBackgroundTask()
  }

  func onEnd(_ call: Call, _ action: CXEndCallAction) {
    action.fulfill()
  }

  func onTimeOut(_ call: Call) {}

  func didActivateAudioSession(_ audioSession: AVAudioSession) {}

  func didDeactivateAudioSession(_ audioSession: AVAudioSession) {}

  func providerDidReset() {}

  private func beginDeclineBackgroundTask() {
    endDeclineBackgroundTask()
    declineTask = UIApplication.shared.beginBackgroundTask(withName: "CallDecline") { [weak self] in
      self?.endDeclineBackgroundTask()
    }
    // Enough for the token request + SignalR connect + CallDeclinedAsync.
    DispatchQueue.main.asyncAfter(deadline: .now() + 20) { [weak self] in
      self?.endDeclineBackgroundTask()
    }
  }

  private func endDeclineBackgroundTask() {
    guard declineTask != .invalid else { return }
    UIApplication.shared.endBackgroundTask(declineTask)
    declineTask = .invalid
  }

  // MARK: - PushKit (VoIP)

  func pushRegistry(_ registry: PKPushRegistry, didUpdate pushCredentials: PKPushCredentials, for type: PKPushType) {
    guard type == .voIP else { return }
    let token = pushCredentials.token.map { String(format: "%02x", $0) }.joined()
    // Persisted by the plugin; read in Dart via FlutterCallkitIncoming.getDevicePushTokenVoIP().
    SwiftFlutterCallkitIncomingPlugin.sharedInstance?.setDevicePushTokenVoIP(token)
  }

  func pushRegistry(_ registry: PKPushRegistry, didInvalidatePushTokenFor type: PKPushType) {
    guard type == .voIP else { return }
    SwiftFlutterCallkitIncomingPlugin.sharedInstance?.setDevicePushTokenVoIP("")
  }

  // iOS 13+: every VoIP push MUST be reported to CallKit before `completion` is called,
  // or iOS terminates the app and eventually stops delivering VoIP pushes to it.
  func pushRegistry(
    _ registry: PKPushRegistry,
    didReceiveIncomingPushWith payload: PKPushPayload,
    for type: PKPushType,
    completion: @escaping () -> Void
  ) {
    guard type == .voIP, let plugin = SwiftFlutterCallkitIncomingPlugin.sharedInstance else {
      completion()
      return
    }

    let data = flutter_callkit_incoming.Data(args: AppDelegate.callKitArgs(from: payload.dictionaryPayload))
    plugin.showCallkitIncoming(data, fromPushKit: true) {
      completion()
    }
  }

  /// Builds the same structure Dart's `CallKitParams.toJson()` produces in
  /// `handleDataMessage` (firebase_notification_manger.dart), so both paths behave identically.
  /// Accepts the call fields at the payload root, or nested under "data"/"extra"/"payload"
  /// (as a dictionary or a JSON string).
  private static func callKitArgs(from raw: [AnyHashable: Any]) -> [String: Any?] {
    var p: [String: Any] = [:]
    for (k, v) in raw { if let key = k as? String { p[key] = v } }
    for key in ["data", "extra", "payload"] {
      if let nested = p[key] as? [String: Any] {
        p.merge(nested) { _, new in new }
      } else if let json = p[key] as? String,
                let d = json.data(using: .utf8),
                let nested = (try? JSONSerialization.jsonObject(with: d)) as? [String: Any] {
        p.merge(nested) { _, new in new }
      }
    }

    func str(_ keys: String...) -> String? {
      for k in keys {
        if let v = p[k], !(v is NSNull) {
          let s = "\(v)"
          if !s.isEmpty { return s }
        }
      }
      return nil
    }

    let callId = str("callId", "sessionId") ?? UUID().uuidString
    // CallKit requires a real UUID; the backend id is kept in `extra.callId`.
    let uuid = UUID(uuidString: callId)?.uuidString ?? UUID().uuidString
    let callerId = str("callerId", "callerEmployeeNumber", "sourceUserId") ?? "unknown"
    let callerName = str("callerName", "callerUserName", "userName") ?? "Unknown Caller"
    let callerEmployeeNumber = str("callerEmployeeNumber") ?? callerId
    let calleeEmployeeNumber = str("calleeEmployeeNumber") ?? callerId
    let isVideoCall: Bool = {
      if let b = p["isVideoCall"] as? Bool { return b }
      if let s = p["isVideoCall"] as? String { return s.lowercased() == "true" }
      return str("callType")?.lowercased() == "video"
    }()

    return [
      "id": uuid,
      "nameCaller": callerName,
      "appName": "ATOMS",
      "avatar": "",
      "handle": callerEmployeeNumber,
      "type": isVideoCall ? 1 : 0,
      "duration": 30000,
      "extra": [
        "callId": callId,
        "callerId": callerId,
        "callerEmployeeNumber": callerEmployeeNumber,
        "calleeEmployeeNumber": calleeEmployeeNumber,
        "callerName": callerName,
        "moduleId": str("moduleId", "applicationId") ?? "",
        "referenceId": str("referenceId") ?? "",
        "conversationId": str("conversationId") ?? "",
        "isVideoCall": isVideoCall,
        "timestamp": ISO8601DateFormatter().string(from: Date()),
      ] as [String: Any],
      "missedCallNotification": [
        "showNotification": true,
        "isShowCallback": false,
        "subtitle": "Missed call",
        "callbackText": "Call back",
      ] as [String: Any],
      "callingNotification": [
        "showNotification": true,
        "isShowCallback": true,
        "subtitle": "Calling...",
        "callbackText": "Hang Up",
      ] as [String: Any],
      "ios": [
        "iconName": "CallKitLogo",
        "handleType": "generic",
        "supportsVideo": true,
        "maximumCallGroups": 1,
        "maximumCallsPerCallGroup": 1,
        // Don't let the plugin activate a playAndRecord audio session while ringing: while the app
        // holds an active session, iOS routes the volume/side buttons to it instead of the CallKit
        // call (no silence on press, no decline on double-press). CallKit activates audio on
        // answer and flutter_webrtc configures it for the call.
        "configureAudioSession": false,
        "audioSessionMode": "default",
        "audioSessionActive": true,
        "audioSessionPreferredSampleRate": 44100.0,
        "audioSessionPreferredIOBufferDuration": 0.005,
        "supportsDTMF": true,
        "supportsHolding": false,
        "supportsGrouping": false,
        "supportsUngrouping": false,
        "ringtonePath": "system_ringtone_default",
      ] as [String: Any],
    ]
  }
}