import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';

import '../firebase_options.dart';
import 'msn_api.dart';

/// Background handler must be a top-level function.
@pragma('vm:entry-point')
Future<void> firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  debugPrint('FCM background: ${message.messageId}');
}

final FlutterLocalNotificationsPlugin _localNotifications = FlutterLocalNotificationsPlugin();

bool _fcmInitialized = false;

/// Call after Firebase.initializeApp. Registers token with [registerPushToken] if API available.
Future<void> initializeFcmAndLocalNotifications(MsnApi api) async {
  if (_fcmInitialized) return;
  _fcmInitialized = true;

  FirebaseMessaging.onBackgroundMessage(firebaseMessagingBackgroundHandler);

  const androidInit = AndroidInitializationSettings('@mipmap/ic_launcher');
  const iosInit = DarwinInitializationSettings();
  await _localNotifications.initialize(
    const InitializationSettings(android: androidInit, iOS: iosInit),
  );

  final messaging = FirebaseMessaging.instance;
  await messaging.setForegroundNotificationPresentationOptions(
    alert: true,
    badge: true,
    sound: true,
  );

  await messaging.requestPermission(alert: true, badge: true, sound: true);

  FirebaseMessaging.onMessage.listen((RemoteMessage msg) async {
    final n = msg.notification;
    final title = n?.title ?? 'IYKYKA';
    final body = n?.body ?? msg.data['body'] as String? ?? '';
    const androidDetails = AndroidNotificationDetails(
      'iykyka_chat',
      '채팅',
      channelDescription: '새 메시지',
      importance: Importance.defaultImportance,
      priority: Priority.defaultPriority,
    );
    const details = NotificationDetails(android: androidDetails);
    await _localNotifications.show(
      msg.hashCode,
      title,
      body,
      details,
    );
  });

  try {
    final token = await messaging.getToken();
    if (token != null && token.isNotEmpty) {
      await api.registerPushToken(token);
      debugPrint('FCM token registered with server');
    }
  } catch (e) {
    debugPrint('FCM getToken/register skipped: $e');
  }

  FirebaseMessaging.instance.onTokenRefresh.listen((token) async {
    try {
      await api.registerPushToken(token);
    } catch (e) {
      debugPrint('FCM token refresh register failed: $e');
    }
  });
}