feat: Add a set of methods to receive notifications

packages/altfire_messenger/lib/altfire_messenger.dart

@@ -3,6 +3,6 @@
 library;
 
 export 'package:firebase_messaging/firebase_messaging.dart'
-    show AuthorizationStatus;
+    show AuthorizationStatus, RemoteMessage;
 
 export 'src/messenger.dart';

packages/altfire_messenger/lib/src/messenger.dart

@@ -1,4 +1,9 @@
+import 'dart:convert';
+
 import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_local_notifications/flutter_local_notifications.dart';
+import 'package:timezone/data/latest.dart' as tz;
 
 /// A class that wraps package for sending notifications and messages.
 /// Its role is to "send necessary notifications and messages to the user".
@@ -8,10 +13,14 @@ import 'package:firebase_messaging/firebase_messaging.dart';
 class Messenger {
   Messenger({
     FirebaseMessaging? messaging,
-  }) : _messaging = messaging ?? FirebaseMessaging.instance;
+    FlutterLocalNotificationsPlugin? notifications,
+  })  : _messaging = messaging ?? FirebaseMessaging.instance,
+        _notifications = notifications ?? FlutterLocalNotificationsPlugin();
 
   final FirebaseMessaging _messaging;
 
+  final FlutterLocalNotificationsPlugin _notifications;
+
   /// Requests notification permissions.
   ///
   /// On iOS, sets the foreground notification presentation options using
@@ -31,4 +40,163 @@ class Messenger {
     final settings = await _messaging.requestPermission();
     return settings;
   }
+
+  /// Returns the current notification settings.
+  Future<NotificationSettings> getNotificationSettings() {
+    return _messaging.getNotificationSettings();
+  }
+
+  /// Receives messages when the app is in the foreground.
+  ///
+  /// Listens to incoming messages and triggers the callback with new data.
+  void onForegroundMessage(ValueChanged<RemoteMessage> onData) {
+    FirebaseMessaging.onMessage.listen(onData);
+  }
+
+  /// Activated when a message is tapped and the app is opened.
+  ///
+  /// This listener handles the event when the app is brought to foreground via a notification tap.
+  void onMessageOpenedApp(ValueChanged<RemoteMessage> onData) {
+    FirebaseMessaging.onMessageOpenedApp.listen(onData);
+  }
+
+  /// Handles receiving messages when the app is in the background.
+  ///
+  /// Must provide a function to process the message data.
+  void onBackgroundMessage(
+    Future<void> Function(RemoteMessage message) handler,
+  ) {
+    FirebaseMessaging.onBackgroundMessage(handler);
+  }
+
+  /// Returns the initial message when the app is opened from a terminated state.
+  ///
+  /// This is useful for handling messages that were received while the app was closed.
+  Future<RemoteMessage?> getInitialMessage() {
+    return _messaging.getInitialMessage();
+  }
+
+  /// Returns the latest FCM token that can be used for device specific messages.
+  Future<String?> getToken() {
+    return _messaging.getToken();
+  }
+
+  /// Listens for token updates and triggers the callback with the new token.
+  ///
+  /// This is important for maintaining a current token for receiving messages.
+  void onTokenRefresh(ValueChanged<String> onData) {
+    _messaging.onTokenRefresh.listen(onData);
+  }
+
+  /// Subscribes the device to a specific topic for grouped messages.
+  Future<void> subscribeToTopic(String topic) {
+    return _messaging.subscribeToTopic(topic);
+  }
+
+  /// Initializes local notifications settings for Android and iOS.
+  ///
+  /// Parameters allow for setting default icon and request permissions.
+  /// Callbacks can be set for handling notification taps.
+  Future<void> initializeNotifications({
+    required String androidDefaultIcon,
+    bool requestAlertPermission = false,
+    bool requestBadgePermission = false,
+    bool requestSoundPermission = false,
+    void Function(int, String?, String?, String?)?
+        onDidReceiveLocalNotification,
+    ValueChanged<Map<String, Object?>>? onNotificationTapped,
+  }) async {
+    tz.initializeTimeZones();
+
+    final androidInitializationSettings =
+        AndroidInitializationSettings(androidDefaultIcon);
+
+    final iOSInitializationSettings = DarwinInitializationSettings(
+      requestAlertPermission: requestAlertPermission,
+      requestBadgePermission: requestBadgePermission,
+      requestSoundPermission: requestSoundPermission,
+      // This property is only applicable to iOS versions older than 10.
+      onDidReceiveLocalNotification: onDidReceiveLocalNotification,
+    );
+
+    final macOSInitializationSettings = DarwinInitializationSettings(
+      requestAlertPermission: requestAlertPermission,
+      requestBadgePermission: requestBadgePermission,
+      requestSoundPermission: requestSoundPermission,
+    );
+
+    await _notifications.initialize(
+      // Settings for how the app appears when it is in the foreground
+      InitializationSettings(
+        android: androidInitializationSettings,
+        iOS: iOSInitializationSettings,
+        macOS: macOSInitializationSettings,
+      ),
+      onDidReceiveNotificationResponse: (response) {
+        onForegroundNotificationTapped(
+          notificationResponse: response,
+          onNotificationTapped: onNotificationTapped,
+        );
+      },
+    );
+  }
+
+  /// Executes when a notification is tapped while the app is in the foreground.
+  ///
+  /// Parses the payload to JSON and triggers the provided callback with the data.
+  @visibleForTesting
+  Future<void> onForegroundNotificationTapped({
+    required NotificationResponse notificationResponse,
+    ValueChanged<Map<String, Object?>>? onNotificationTapped,
+  }) async {
+    final payload = notificationResponse.payload;
+    debugPrint('Notification tapped in foreground. payload: $payload');
+    if (payload != null && onNotificationTapped != null) {
+      final jsonMap = jsonDecode(payload) as Map<String, dynamic>;
+      onNotificationTapped(jsonMap);
+    }
+  }
+
+  /// Displays a notification with customizable settings.
+  ///
+  /// Can specify the notification channel, description, icon, and color among others.
+  Future<void> showNotification({
+    required String channelId,
+    required String channelName,
+    required String channelDescription,
+    required String icon,
+    required Color color,
+    required int id,
+    String? title,
+    String? body,
+    Map<String, dynamic>? payloadJsonMap,
+  }) async {
+    final androidPlatformChannelSpecifics = AndroidNotificationDetails(
+      channelId,
+      channelName,
+      channelDescription: channelDescription,
+      icon: icon,
+      importance: Importance.max,
+      priority: Priority.high,
+      color: color,
+    );
+
+    final iOSPlatformChannelSpecifics = DarwinNotificationDetails();
+
+    final macOSPlatformChannelSpecifics = DarwinNotificationDetails();
+
+    final platformChannelSpecifics = NotificationDetails(
+      android: androidPlatformChannelSpecifics,
+      iOS: iOSPlatformChannelSpecifics,
+      macOS: macOSPlatformChannelSpecifics,
+    );
+
+    await _notifications.show(
+      id,
+      title,
+      body,
+      platformChannelSpecifics,
+      payload: jsonEncode(payloadJsonMap),
+    );
+  }
 }

packages/altfire_messenger/pubspec.yaml

@@ -19,6 +19,8 @@ dependencies:
   firebase_messaging: ^15.0.3
   flutter:
     sdk: flutter
+  flutter_local_notifications: ^17.2.2
+  timezone: ^0.9.4
 
 dev_dependencies:
   altive_lints: ^1.10.0