import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:audioplayers/audioplayers.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'firebase_options.dart';
import 'providers/profile_provider.dart';
import 'models/profile.dart';

import 'app.dart';

import 'providers/notifications_provider.dart';
import 'utils/app_time.dart';
import 'utils/notification_permission.dart';
import 'services/notification_service.dart';
import 'services/notification_bridge.dart';

/// Handle messages received while the app is terminated or in background.
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // initialize plugin in background isolate
  await NotificationService.initialize();
  final notification = message.notification;
  if (notification != null) {
    NotificationService.show(
      id: DateTime.now().millisecondsSinceEpoch ~/ 1000,
      title: notification.title ?? 'Notification',
      body: notification.body ?? '',
      payload: message.data['payload'],
    );
  }
}

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // initialize Firebase before anything that uses messaging
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

  await dotenv.load(fileName: '.env');

  AppTime.initialize(location: 'Asia/Manila');

  final supabaseUrl = dotenv.env['SUPABASE_URL'] ?? '';
  final supabaseAnonKey = dotenv.env['SUPABASE_ANON_KEY'] ?? '';

  if (supabaseUrl.isEmpty || supabaseAnonKey.isEmpty) {
    runApp(const _MissingConfigApp());
    return;
  }

  await Supabase.initialize(url: supabaseUrl, anonKey: supabaseAnonKey);

  // ensure token saved right away if already signed in
  final supaClient = Supabase.instance.client;
  String? initialToken;
  if (!kIsWeb) {
    try {
      initialToken = await FirebaseMessaging.instance.getToken();
    } catch (e) {
      debugPrint('FCM getToken failed: $e');
      initialToken = null;
    }
    if (initialToken != null && supaClient.auth.currentUser != null) {
      debugPrint('initial FCM token for signed-in user: $initialToken');
      final ctrl = NotificationsController(supaClient);
      await ctrl.registerFcmToken(initialToken);
    }
  }

  // listen for auth changes to register/unregister token accordingly
  supaClient.auth.onAuthStateChange.listen((data) async {
    final event = data.event;
    if (kIsWeb) {
      debugPrint(
        'auth state change $event on web: skipping FCM token handling',
      );
      return;
    }
    String? token;
    try {
      token = await FirebaseMessaging.instance.getToken();
    } catch (e) {
      debugPrint('FCM getToken failed during auth change: $e');
      token = null;
    }
    debugPrint('auth state change $event, token=$token');
    if (token == null) return;
    final ctrl = NotificationsController(supaClient);
    if (event == AuthChangeEvent.signedIn) {
      await ctrl.registerFcmToken(token);
    } else if (event == AuthChangeEvent.signedOut) {
      await ctrl.unregisterFcmToken(token);
    }
  });

  if (!kIsWeb) {
    // on Android 13+ we must request POST_NOTIFICATIONS at runtime; without it
    // notifications are automatically denied and cannot be re‑enabled from the
    // system settings. The helper uses `permission_handler`.
    final granted = await ensureNotificationPermission();
    if (!granted) {
      // we don’t block startup, but it’s worth logging so developers notice.
      // A real app might show a dialog pointing the user to settings.
      // debugPrint('notification permission not granted');
    }

    // request FCM permission (iOS/Android13+) and handle foreground messages
    await FirebaseMessaging.instance.requestPermission();
  }
  FirebaseMessaging.onMessage.listen((RemoteMessage message) {
    final notification = message.notification;
    if (notification != null) {
      NotificationService.show(
        id: DateTime.now().millisecondsSinceEpoch ~/ 1000,
        title: notification.title ?? 'Notification',
        body: notification.body ?? '',
        payload: message.data['payload'],
      );
    }
  });

  // initialize the local notifications plugin so we can post alerts later
  await NotificationService.initialize(
    onDidReceiveNotificationResponse: (response) {
      // handle user tapping a notification; the payload format is up to us
      final payload = response.payload;
      if (payload != null && payload.startsWith('ticket:')) {
        // ignore if context not mounted; we might use a navigator key in real
        // app, but keep this simple for now
        // TODO: navigate to ticket/task as appropriate
      }
    },
  );

  // global navigator key used for snackbars/navigation from notification
  final navigatorKey = GlobalKey<NavigatorState>();

  runApp(
    ProviderScope(
      observers: [NotificationSoundObserver()],
      child: NotificationBridge(
        navigatorKey: navigatorKey,
        child: const TasqApp(),
      ),
    ),
  );
}

class NotificationSoundObserver extends ProviderObserver {
  static final AudioPlayer _player = AudioPlayer();
  StreamSubscription<String?>? _tokenSub;

  @override
  void didUpdateProvider(
    ProviderBase provider,
    Object? previousValue,
    Object? newValue,
    ProviderContainer container,
  ) {
    // play sound + show OS notification on unread-count increase
    if (provider == unreadNotificationsCountProvider) {
      final prev = previousValue as int?;
      final next = newValue as int?;
      if (prev != null && next != null && next > prev) {
        _player.play(AssetSource('tasq_notification.wav'));
        NotificationService.show(
          id: DateTime.now().millisecondsSinceEpoch ~/ 1000,
          title: 'New notifications',
          body: 'You have $next unread notifications.',
        );
      }
    }

    // when profile changes, register or unregister tokens
    if (provider == currentProfileProvider) {
      final profile = newValue as Profile?;
      final controller = container.read(notificationsControllerProvider);

      if (profile != null) {
        // signed in: save current token and keep listening for refreshes
        if (!kIsWeb) {
          FirebaseMessaging.instance
              .getToken()
              .then((token) {
                if (token != null) {
                  debugPrint('profile observer registering token: $token');
                  controller.registerFcmToken(token);
                }
              })
              .catchError((e) => debugPrint('getToken error: $e'));
          _tokenSub = FirebaseMessaging.instance.onTokenRefresh.listen((token) {
            debugPrint('token refreshed: $token');
            controller.registerFcmToken(token);
          });
        }
      } else {
        // signed out: unregister whatever token we currently have
        _tokenSub?.cancel();
        if (!kIsWeb) {
          FirebaseMessaging.instance
              .getToken()
              .then((token) {
                if (token != null) {
                  debugPrint('profile observer unregistering token: $token');
                  controller.unregisterFcmToken(token);
                }
              })
              .catchError((e) => debugPrint('getToken error: $e'));
        }
      }
    }
  }
}

class _MissingConfigApp extends StatelessWidget {
  const _MissingConfigApp();

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: Scaffold(
        body: Center(
          child: Padding(
            padding: EdgeInsets.all(24),
            child: Text(
              'Missing SUPABASE_URL or SUPABASE_ANON_KEY. '
              'Provide them in the .env file.',
              textAlign: TextAlign.center,
            ),
          ),
        ),
      ),
    );
  }
}