firebaseCM/fcm/app/src/main/java/com/example/fcm/MyFirebaseMessagingService.java

package com.example.fcm;

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Build;
import android.util.Log;

import androidx.annotation.RequiresApi;
import androidx.core.app.NotificationCompat;
import androidx.work.OneTimeWorkRequest;
import androidx.work.WorkManager;

import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

import java.util.Random;

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    private final String ADMIN_CHANNEL_ID ="admin_channel";
    private static final String TAG = "MyFirebaseMsgService";
    private static final String FIREBASE_URL = "https://fcmfirebaseproject-ececa.firebaseio.com";

    /**
     * Called when message is received.
     *
     * @param remoteMessage Object representing the message received from Firebase Cloud Messaging.
     */
    // [START receive_message]
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        // [START_EXCLUDE]
        // There are two types of messages data messages and notification messages. Data messages
        // are handled
        // here in onMessageReceived whether the app is in the foreground or background. Data
        // messages are the type
        // traditionally used with GCM. Notification messages are only received here in
        // onMessageReceived when the app
        // is in the foreground. When the app is in the background an automatically generated
        // notification is displayed.
        // When the user taps on the notification they are returned to the app. Messages
        // containing both notification
        // and data payloads are treated as notification messages. The Firebase console always
        // sends notification
        // messages. For more see: https://firebase.google.com/docs/cloud-messaging/concept-options
        // [END_EXCLUDE]

        // TODO(developer): Handle FCM messages here.
        // Not getting messages here? See why this may be: https://goo.gl/39bRNJ
        final Intent intent = new Intent(this, MainActivity.class);
        NotificationManager notificationManager = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
        int notificationID = new Random().nextInt(3000);

        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
            setupChannels(notificationManager);
        }

        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this , 0, intent,
                PendingIntent.FLAG_ONE_SHOT);


        Uri notificationSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, ADMIN_CHANNEL_ID)
                .setSmallIcon(R.drawable.ic_stat_ic_notification)
                .setContentTitle(remoteMessage.getData().get("title"))
                .setContentText(remoteMessage.getData().get("message"))
                .setAutoCancel(true)
                .setSound(notificationSoundUri)
                .setContentIntent(pendingIntent);

        notificationManager.notify(notificationID, notificationBuilder.build());

        Log.d(TAG, "From: " + remoteMessage.getFrom());

        // Check if message contains a data payload.
        if (remoteMessage.getData().size() > 0) {
            Log.d(TAG, "Message data payload: " + remoteMessage.getData());

            if (/* Check if data needs to be processed by long running job */ true) {
                // For long-running tasks (10 seconds or more) use WorkManager.
                scheduleJob();
            } else {
                // Handle message within 10 seconds
                handleNow();
            }

        }

        // Check if message contains a notification payload.
        if (remoteMessage.getNotification() != null) {
            Log.d(TAG, "Message Notification Body: " + remoteMessage.getNotification().getBody());
        }

        // Also if you intend on generating your own notifications as a result of a received FCM
        // message, here is where that should be initiated. See sendNotification method below.
    }
    // [END receive_message]


    // [START on_new_token]

    /**
     * Called if InstanceID token is updated. This may occur if the security of
     * the previous token had been compromised. Note that this is called when the InstanceID token
     * is initially generated so this is where you would retrieve the token.
     */
    @Override
    public void onNewToken(String token) {
        Log.d(TAG, "Refreshed token: " + token);

        // If you want to send messages to this application instance or
        // manage this apps subscriptions on the server side, send the
        // Instance ID token to your app server.
        sendRegistrationToServer(token);
    }
    // [END on_new_token]

    /**
     * Schedule async work using WorkManager.
     */
    private void scheduleJob() {
        // [START dispatch_job]
        OneTimeWorkRequest work = new OneTimeWorkRequest.Builder(MyWorker.class)
                .build();
        WorkManager.getInstance().beginWith(work).enqueue();
        // [END dispatch_job]
    }

    /**
     * Handle time allotted to BroadcastReceivers.
     */
    private void handleNow() {
        Log.d(TAG, "Short lived task is done.");
    }

    /**
     * Persist token to third-party servers.
     *
     * Modify this method to associate the user's FCM InstanceID token with any server-side account
     * maintained by your application.
     *
     * @param token The new token.
     */
    private void sendRegistrationToServer(String token) {
        // TODO: Implement this method to send token to your app server.
    }

    /**
     * Create and show a simple notification containing the received FCM message.
     *
     * @param messageBody FCM message body received.
     */
    private void sendNotification(String messageBody) {
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
                PendingIntent.FLAG_ONE_SHOT);

        String channelId = getString(R.string.default_notification_channel_id);
        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder =
                new NotificationCompat.Builder(this, channelId)
                        .setSmallIcon(R.drawable.ic_stat_ic_notification)
                        .setContentTitle(getString(R.string.fcm_message))
                        .setContentText(messageBody)
                        .setAutoCancel(true)
                        .setSound(defaultSoundUri)
                        .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        // Since android Oreo notification channel is needed.
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel channel = new NotificationChannel(channelId,
                    "Channel human readable title",
                    NotificationManager.IMPORTANCE_DEFAULT);
            notificationManager.createNotificationChannel(channel);
        }

        notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());
    }

    //public static void sendNotificationToUser(String user, final String message) {
    //   Firebase ref = new Firebase(FIREBASE_URL);
    //    final Firebase notifications = ref.child("notificationRequests");

    //Map notification = new HashMap<>();
    //    notification.put("username", user);
    //    notification.put("message", message);

    //   notifications.push().setValue(notification);
    //}

    @RequiresApi(api = Build.VERSION_CODES.O)
    private void setupChannels(NotificationManager notificationManager){
        CharSequence adminChannelName = "New notification";
        String adminChannelDescription = "Device to devie notification";

        NotificationChannel adminChannel;
        adminChannel = new NotificationChannel(ADMIN_CHANNEL_ID, adminChannelName, NotificationManager.IMPORTANCE_HIGH);
        adminChannel.setDescription(adminChannelDescription);
        adminChannel.enableLights(true);
        adminChannel.setLightColor(Color.RED);
        adminChannel.enableVibration(true);
        if (notificationManager != null) {
            notificationManager.createNotificationChannel(adminChannel);
        }
    }



}