import 'dart:async';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';

class NotificationHelper {
  static final NotificationHelper instance = NotificationHelper._init();
  final StreamController<String> notificationStreamController = StreamController<String>.broadcast();
  Stream<String> get notificationStream => notificationStreamController.stream;
  final FlutterLocalNotificationsPlugin _notificationsPlugin =
      FlutterLocalNotificationsPlugin();
  bool _isInitialized = false;

  NotificationHelper._init();

  Future<void> init() async {
    const AndroidInitializationSettings initializationSettingsAndroid =
        AndroidInitializationSettings('@mipmap/ic_launcher');

    const InitializationSettings initializationSettings =
        InitializationSettings(
      android: initializationSettingsAndroid,
    );

    await _notificationsPlugin.initialize(
      initializationSettings,
      onDidReceiveNotificationResponse: (details) {
        if (details.payload != null) {
          // This will be handled by the UI listening to a stream or similar
          // or we can use a global navigator key if available.
          // For now, we'll use a static notificationStream to let listeners know.
          notificationStreamController.add(details.payload!);
        }
      },
    );
    _isInitialized = true;
  }

  Future<void> showNotification({
    required int id,
    required String title,
    required String body,
    String? payload,
  }) async {
    if (!_isInitialized) await init();

    const AndroidNotificationDetails androidPlatformChannelSpecifics =
        AndroidNotificationDetails(
      'sms_channel',
      'SMS Notifications',
      channelDescription: 'Notifications for incoming secure messages',
      importance: Importance.max,
      priority: Priority.high,
      showWhen: true,
    );

    const NotificationDetails platformChannelSpecifics = NotificationDetails(
      android: androidPlatformChannelSpecifics,
    );

    await _notificationsPlugin.show(
      id,
      title,
      body,
      platformChannelSpecifics,
      payload: payload,
    );
  }
}