Firebase Cloud Messaging (FCM)

Get Access Token

• Got to Google OAuth Playground: https://developers.google.com/oauthplayground
• In the "Input your own scopes" for FCM use this url: https://www.googleapis.com/auth/firebase.messaging
• Tap Authorize API.
• Pick correct user for authorisation and allow access.
• In the Step 2: Exchange authorization code for tokens tap Exchange authorisation code for tokens.
• Access token is your Bearer.

Reference

config/fcm.dart

import 'dart:convert';
import 'dart:developer';

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter_local_notif_fcm/config/local_notif.dart';
import 'package:flutter_local_notif_fcm/main.dart';

@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  log("background!");
  _showCustomNotif(message);
}

void _handleMessage(RemoteMessage message) {
  Map data = message.data;

  if (data.containsKey('navigate_to')) {
    navigatorKey.currentState?.pushNamed(data['navigate_to']);
  }
}

void _showCustomNotif(RemoteMessage message) {
  // if (message.notification != null) {
  //   LocalNotif.showNotif(
  //     id: message.hashCode,
  //     title: message.notification!.title,
  //     body: message.notification!.body,
  //     payload: jsonEncode(message.data),
  //   );
  // }

  if (message.data.containsKey('notif_title')) {
    LocalNotif.showNotif(
      id: message.hashCode,
      title: message.data['notif_title'],
      body: message.data['notif_body'],
      payload: jsonEncode(message.data),
    );
  }
}

class FCM {
  static Future<void> init() async {
    await FirebaseMessaging.instance.setAutoInitEnabled(true);
    final settings = await FirebaseMessaging.instance.requestPermission();
    log('User granted permission: ${settings.authorizationStatus}');
    _foregroundHandler();
    _backgroundHandler();
    _listenOpenNotif();
  }

  static _foregroundHandler() {
    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      log('foreground!');
      _showCustomNotif(message);
    });
  }

  static _backgroundHandler() {
    FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
  }

  // for terminate state
  static initialMessage() async {
    RemoteMessage? initialMessage =
        await FirebaseMessaging.instance.getInitialMessage();
    if (initialMessage != null) {
      _handleMessage(initialMessage);
    }
  }

  static _listenOpenNotif() {
    FirebaseMessaging.onMessageOpenedApp.listen(_handleMessage);
  }
}