buildscript {
      dependencies {
          classpath 'com.google.gms:google-services:4.4.2'
      }
  }
  
  In your app-level build.gradle:
  plugins {
      id 'com.android.application'
      id 'com.google.gms.google-services'
  }
  
  dependencies {
      // Firebase BoM
      implementation platform('com.google.firebase:firebase-bom:33.14.0')
  
      // Firebase Cloud Messaging
      implementation 'com.google.firebase:firebase-messaging'
  }      
      

  <uses-permission android:name="android.permission.INTERNET" />

  <application>
      <service
          android:name=".MyFirebaseMessagingService"
          android:exported="false">
          <intent-filter>
              <action android:name="com.google.firebase.MESSAGING_EVENT" />
          </intent-filter>
      </service>
  </application>            
      

  fun createNotificationChannel(context: Context) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        val channel = NotificationChannel(
            "default_channel",
            "Default Channel",
            NotificationManager.IMPORTANCE_DEFAULT
        )
        val manager = context.getSystemService(NotificationManager::class.java)
        manager?.createNotificationChannel(channel)
    }
  }          
      

  class MyFirebaseMessagingService : FirebaseMessagingService() {

    override fun onNewToken(token: String) {
        super.onNewToken(token)
        Log.d("FCM", "New token: $token")
        // Send this token to your server if needed
    }

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        super.onMessageReceived(remoteMessage)

        val title = remoteMessage.notification?.title ?: "Default Title"
        val message = remoteMessage.notification?.body ?: "Default Message"

        showNotification(title, message)
    }

    private fun showNotification(title: String, message: String) {
        val intent = Intent(this, MainActivity::class.java)
        val pendingIntent = PendingIntent.getActivity(
            this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
        )

        val notification = NotificationCompat.Builder(this, "default_channel")
            .setSmallIcon(R.drawable.ic_notification)
            .setContentTitle(title)
            .setContentText(message)
            .setAutoCancel(true)
            .setContentIntent(pendingIntent)
            .build()

        val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        manager.notify(0, notification)
    }
  }          
      

  curl -X POST -H "Authorization: key=YOUR_SERVER_KEY" \
  -H "Content-Type: application/json" \
  -d '{
      "to": "YOUR_DEVICE_FCM_TOKEN",
      "notification": {
      "title": "Hello!",
      "body": "This is a test push notification"
      }
  }' https://fcm.googleapis.com/fcm/send