flutter-freaccess-hub/lib/backend/push_notification/push_notification.dart

import 'dart:async';
import 'dart:developer';

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 'package:hub/firebase_options.dart';

class NotificationService {
  // Singleton instance
  static final NotificationService _instance = NotificationService._internal();

  // Factory constructor
  factory NotificationService() => _instance;

  // Private constructor
  NotificationService._internal();

  static final FirebaseMessaging _firebaseMessaging =
      FirebaseMessaging.instance;
  static final FlutterLocalNotificationsPlugin
      _flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
  static bool _initialized = false;

  Future<void> initialize() async {
    if (_initialized) return;
    _initialized = true;

    try {
      await _requestPermissions();
      await _initializeLocalNotifications();

      FirebaseMessaging.onBackgroundMessage(
          _firebaseMessagingBackgroundHandler);

      FirebaseMessaging.onMessage.listen((RemoteMessage message) {
        _printNotification(message, 'onMessage');
      });

      FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
        _printNotification(message, 'onMessageOpenedApp');
      });
    } catch (e) {
      log('Error initializing notification manager: $e');
    }
  }

  Future<void> _printNotification(RemoteMessage message, String type) async {
    log('Notification $type: ${message.messageId}');
    // Handle the notification display logic here
  }

  Future<void> _initializeLocalNotifications() async {
    const AndroidInitializationSettings initializationSettingsAndroid =
        AndroidInitializationSettings('@mipmap/ic_launcher');
    final DarwinInitializationSettings initializationSettingsIOS =
        DarwinInitializationSettings(
      onDidReceiveLocalNotification:
          (int id, String? title, String? body, String? payload) async {
        // Handle the notification received in foreground
      },
    );
    final InitializationSettings initializationSettings =
        InitializationSettings(
      android: initializationSettingsAndroid,
      iOS: initializationSettingsIOS,
    );

    await _flutterLocalNotificationsPlugin.initialize(initializationSettings,
        onDidReceiveNotificationResponse: (payload) async =>
            log('Notification tapped: $payload'),
        onDidReceiveBackgroundNotificationResponse: (payload) async =>
            log('Notification tapped in background: $payload'));
  }

  Future<void> _requestPermissions() async {
    NotificationSettings settings = await _firebaseMessaging.requestPermission(
      alert: true,
      announcement: false,
      badge: true,
      carPlay: false,
      criticalAlert: false,
      provisional: false,
      sound: true,
    );

    log('User granted permission: ${settings.authorizationStatus}');
  }

  Future<void> subscribeToTopic(String topic) async {
    try {
      await _firebaseMessaging.subscribeToTopic(topic);
      log('Subscribed to topic: $topic');
    } catch (e) {
      log('Error subscribing to topic $topic: $e');
    }
  }

  Future<void> unsubscribeFromTopic(String topic) async {
    try {
      await _firebaseMessaging.unsubscribeFromTopic(topic);
      log('Unsubscribed from topic: $topic');
    } catch (e) {
      log('Error unsubscribing from topic $topic: $e');
    }
  }
}

@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  await setupFlutterNotifications();
  showFlutterNotification(message);
  // If you're going to use other Firebase services in the background, such as Firestore,
  // make sure you call `initializeApp` before using other Firebase services.
  log('Handling a background message ${message.messageId}');
}

/// Create a [AndroidNotificationChannel] for heads up notifications
late AndroidNotificationChannel channel;

bool isFlutterLocalNotificationsInitialized = false;

Future<void> setupFlutterNotifications() async {
  if (isFlutterLocalNotificationsInitialized) {
    return;
  }
  channel = const AndroidNotificationChannel(
    'high_importance_channel', // id
    'High Importance Notifications', // title
    description:
        'This channel is used for important notifications.', // description
    importance: Importance.high,
  );

  flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();

  /// Create an Android Notification Channel.
  ///
  /// We use this channel in the `AndroidManifest.xml` file to override the
  /// default FCM channel to enable heads up notifications.
  await flutterLocalNotificationsPlugin
      .resolvePlatformSpecificImplementation<
          AndroidFlutterLocalNotificationsPlugin>()
      ?.createNotificationChannel(channel);

  /// Update the iOS foreground notification presentation options to allow
  /// heads up notifications.
  await FirebaseMessaging.instance.setForegroundNotificationPresentationOptions(
    alert: true,
    badge: true,
    sound: true,
  );
  isFlutterLocalNotificationsInitialized = true;
}

void showFlutterNotification(RemoteMessage message) {
  RemoteNotification? notification = message.notification;
  AndroidNotification? android = message.notification?.android;
  if (notification != null && android != null && !kIsWeb) {
    flutterLocalNotificationsPlugin.show(
      notification.hashCode,
      notification.title,
      notification.body,
      NotificationDetails(
        android: AndroidNotificationDetails(
          channel.id,
          channel.name,
          channelDescription: channel.description,
          // TODO add a proper drawable resource to android, for now using
          //      one that already exists in example app.
          icon: 'launch_background',
        ),
      ),
    );
  }
}

/// Initialize the [FlutterLocalNotificationsPlugin] package.
late FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;