mohemm-flutter-app/lib/classes/push-notification-handler.dart

import 'dart:async';
import 'dart:io';

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:mohem_flutter_app/app_state/app_state.dart';

// |--> Push Notification Background
Future<dynamic> backgroundMessageHandler(message) async {
  print("Firebase backgroundMessageHandler!!!");
}

class PushNotificationHandler {
  final BuildContext context;
  static PushNotificationHandler? _instance;

  PushNotificationHandler(this.context) {
    PushNotificationHandler._instance = this;
  }

  static PushNotificationHandler getInstance() => _instance!;

  void init() async {
    FirebaseMessaging.onMessage.listen((RemoteMessage message) async {
      if (Platform.isIOS) {
        await Future.delayed(Duration(milliseconds: 3000)).then((value) {
          newMessage(message);
        });
      } else {
        newMessage(message);
      }
    });

    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) async {
      if (Platform.isIOS) {
        await Future.delayed(Duration(milliseconds: 3000)).then((value) {
          newMessage(message);
        });
      } else {
        newMessage(message);
      }
    });

    FirebaseMessaging.instance.onTokenRefresh.listen((fcm_token) {
      print("Push Notification onTokenRefresh: " + fcm_token);
      AppState().setDeviceToken = fcm_token;
    });

    FirebaseMessaging.onBackgroundMessage(backgroundMessageHandler);
  }

  void newMessage(RemoteMessage remoteMessage) async {
    print("Remote Message: " + remoteMessage.data.toString());
    if (remoteMessage.data.isEmpty) {
      return;
    }
  }
}