Push Notification for Flutter

import 'dart:convert';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:get/get.dart';
import 'package:leap_counsellor_chat_and_call_app/sendbird/color.dart';
import 'package:leap_counsellor_chat_and_call_app/sendbird/components/push_notification.dart';
import 'package:leap_counsellor_chat_and_call_app/sendbird/main_binding.dart';
import 'package:leap_counsellor_chat_and_call_app/sendbird/routes.dart';
import 'package:leap_counsellor_chat_and_call_app/sendbird/util/notification_service.dart';
import 'package:notification_permissions/notification_permissions.dart';
import 'package:universal_io/io.dart';

import 'Constants/SharedPreferencehelper.dart';

Future _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  print("Handling background message: ${message.messageId}");

  String? channelUrl = null;
  if (message.data.containsKey('sendbird')) {
    final sendBird = json.decode(message.data['sendbird']);
    final channel = sendBird['channel'];
    channelUrl = channel['channel_url'];
    final sender = sendBird['sender'];

    NotificationService.showNotification(
      sender['name'] ?? '',
      sendBird['message'] ?? '',
    );
  }
}

late String permissionStatusFuture;

var permGranted = "granted";
var permDenied = "denied";
var permUnknown = "unknown";
var permProvisional = "provisional";

Future<void> checkPNPermissions() async {
  permissionStatusFuture = await getCheckNotificationPermStatus();
  if (permissionStatusFuture != permGranted) {
    // show the dialog/open settings screen
    NotificationPermissions.requestNotificationPermissions(
            iosSettings: const NotificationSettingsIos(
                sound: true, badge: true, alert: true))
        .then((_) async {
      // when finished, check the permission status
      permissionStatusFuture = await getCheckNotificationPermStatus();
      if (permissionStatusFuture != permGranted) {}
    });
  }
}

Future<String> getCheckNotificationPermStatus() {
  return NotificationPermissions.getNotificationPermissionStatus()
      .then((status) {
    switch (status) {
      case PermissionStatus.denied:
        return permDenied;
      case PermissionStatus.granted:
        return permGranted;
      case PermissionStatus.unknown:
        return permUnknown;
      case PermissionStatus.provisional:
        return permProvisional;
      default:
        return permUnknown;
    }
  });
}

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await checkPNPermissions();
  //Use DefaultFirebaseOptions to allow web app
  await Firebase.initializeApp();
  await SharedPrefs.instance.init();
  return runApp(const MyApp());
}

final appState = AppState();

class AppState with ChangeNotifier {
  bool didRegisterToken = false;
  String? token;
  String? destChannelUrl;

  void setDestination(String? channelUrl) {
    destChannelUrl = channelUrl;
    notifyListeners();
  }
}

const AndroidNotificationChannel channel = AndroidNotificationChannel(
  'high_importance_channel', // id
  'High Importance Notifications', // title
  description:
      'This channel is used for important notifications.', // description
  importance: Importance.high,
  playSound: true,
);

final FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
    FlutterLocalNotificationsPlugin();

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  MyAppState createState() => MyAppState();
}

class MyAppState extends State<MyApp> {
  late int _totalNotifications;
  late final FirebaseMessaging _messaging;
  PushNotification? _notificationInfo;

  // [Push Notification Set Up]
  void requestAndRegisterNotification() async {
    // Initialize the Firebase app
    await Firebase.initializeApp();

    // Instantiate Firebase Messaging
    _messaging = FirebaseMessaging.instance;
    FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

    // To enable foreground notification in firebase messaging for IOS
    await FirebaseMessaging.instance
        .setForegroundNotificationPresentationOptions(
      alert: true, // Required to display a heads up notification
      badge: true,
      sound: true,
    );

    // On iOS, this helps to take the user permissions
    NotificationSettings settings = await _messaging.requestPermission(
      alert: true,
      badge: true,
      provisional: false,
      sound: true,
    );

    if (settings.authorizationStatus == AuthorizationStatus.authorized) {
      print('User granted permission');
      String? token;

      if (Platform.isIOS) {
        //Retrieve pushtoken for IOS
        token = await _messaging.getAPNSToken();
      } else {
        // Retrieve pushtoken for FCM
        token = await _messaging.getToken();
      }

      print("SAVING FCM TOKEN TO SERVER = $token");
      await SharedPrefs.instance.setString(SharedPrefs.FCM_TOKEN, token!);
      appState.token = token;
      // For handling the received notifications
      FirebaseMessaging.onMessage.listen((RemoteMessage message) {
        print('title: ${message.notification?.title}');
        print('body: ${message.notification?.body}');
        // Parse the message received
        PushNotification notification = PushNotification(
          title: message.notification?.title,
          body: message.notification?.body,
        );

        setState(() {
          _notificationInfo = notification;
          _totalNotifications++;
        });
        if (_notificationInfo != null) {
          NotificationService.showNotification(
              _notificationInfo?.title ?? '', _notificationInfo?.body ?? '');
        }
      });
    } else {
      print('User declined or has not accepted permission');
    }
  }

  @override
  void initState() {
    requestAndRegisterNotification();
    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      PushNotification notification = PushNotification(
        title: message.notification?.title,
        body: message.notification?.body,
      );
      setState(() {
        _notificationInfo = notification;
        _totalNotifications++;
      });
    });
    _totalNotifications = 0;
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      theme: ThemeData(
        primaryColor: appPrimaryColor,
      ),
      debugShowCheckedModeBanner: false,
      title: 'Leap Counsellor App',
      initialRoute: "/RootRoute",
      getPages: routes,
      initialBinding: MainBinding(),
    );
  }
}