Notifications & FCM Delivery

Copy code// build.gradle.kts
implementation("com.google.firebase:firebase-messaging-ktx:23.4.1")

Copy codeclass AppMessagingService : FirebaseMessagingService() {

    // Called when a new FCM token is generated (first run or token refresh)
    override fun onNewToken(token: String) {
        // Send this token to your server so it can send push notifications
        CoroutineScope(Dispatchers.IO + SupervisorJob()).launch {
            serverApi.updateDeviceToken(token)
        }
    }

    // Called for ALL data messages; called for notification messages only when app is foreground
    override fun onMessageReceived(message: RemoteMessage) {
        val notificationType = message.data["type"] ?: return

        when (notificationType) {
            "new_message" -> handleNewMessage(message)
            "like" -> handleLikeNotification(message)
            "comment" -> handleCommentNotification(message)
        }
    }
}

Copy codefun createNotificationChannels(context: Context) {
    val notificationManager = context.getSystemService(NotificationManager::class.java)

    val channels = listOf(
        NotificationChannel(
            "messages",
            "Messages",
            NotificationManager.IMPORTANCE_HIGH
        ).apply {
            description = "New message notifications"
            enableVibration(true)
            setShowBadge(true)
        },
        NotificationChannel(
            "social",
            "Likes & Comments",
            NotificationManager.IMPORTANCE_DEFAULT
        ).apply {
            description = "Likes, comments, and follows"
        },
        NotificationChannel(
            "system",
            "System",
            NotificationManager.IMPORTANCE_LOW
        ).apply {
            description = "Account and security notifications"
        }
    )

    channels.forEach { notificationManager.createNotificationChannel(it) }
}

Copy codeprivate fun handleNewMessage(message: RemoteMessage) {
    val senderId = message.data["sender_id"] ?: return
    val senderName = message.data["sender_name"] ?: "Someone"
    val body = message.data["body"] ?: ""
    val conversationId = message.data["conversation_id"] ?: return

    // Deep link intent — opens the conversation when tapped
    val intent = Intent(this, MainActivity::class.java).apply {
        flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TOP
        putExtra("destination", "conversation")
        putExtra("conversation_id", conversationId)
    }
    val pendingIntent = PendingIntent.getActivity(
        this, conversationId.hashCode(), intent,
        PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
    )

    val notification = NotificationCompat.Builder(this, "messages")
        .setSmallIcon(R.drawable.ic_notification)
        .setContentTitle(senderName)
        .setContentText(body)
        .setStyle(NotificationCompat.BigTextStyle().bigText(body))
        .setContentIntent(pendingIntent)
        .setAutoCancel(true)  // dismiss on tap
        .setPriority(NotificationCompat.PRIORITY_HIGH)
        .setCategory(NotificationCompat.CATEGORY_MESSAGE)
        .setShortcutId(senderId)  // link to conversation shortcut for People API
        .build()

    NotificationManagerCompat.from(this)
        .notify(conversationId.hashCode(), notification)
}

Copy codeclass MainActivity : AppCompatActivity() {
    private val requestPermissionLauncher = registerForActivityResult(
        ActivityResultContracts.RequestPermission()
    ) { isGranted ->
        if (!isGranted) showRationale()
    }

    fun requestNotificationPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
            when {
                ContextCompat.checkSelfPermission(
                    this, Manifest.permission.POST_NOTIFICATIONS
                ) == PackageManager.PERMISSION_GRANTED -> { /* already granted */ }

                shouldShowRequestPermissionRationale(Manifest.permission.POST_NOTIFICATIONS) ->
                    showRationale()

                else ->
                    requestPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
            }
        }
    }
}

Copy code// In MainActivity.onCreate and onNewIntent:
override fun onNewIntent(intent: Intent) {
    super.onNewIntent(intent)
    handleNotificationDeepLink(intent)
}

private fun handleNotificationDeepLink(intent: Intent) {
    when (intent.getStringExtra("destination")) {
        "conversation" -> {
            val conversationId = intent.getStringExtra("conversation_id") ?: return
            navController.navigate("conversation/$conversationId")
        }
        "article" -> {
            val articleId = intent.getStringExtra("article_id") ?: return
            navController.navigate("article/$articleId")
        }
    }
}