Firebase Cloud Messaging for push notifications

package com.example.myapp.services

import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.os.Build
import androidx.core.app.NotificationCompat
import com.example.myapp.R
import com.example.myapp.ui.MainActivity
import com.google.firebase.messaging.FirebaseMessagingService
import com.google.firebase.messaging.RemoteMessage
import dagger.hilt.android.AndroidEntryPoint
import javax.inject.Inject

@AndroidEntryPoint
class MyFirebaseMessagingService : FirebaseMessagingService() {

    @Inject
    lateinit var tokenManager: TokenManager

    override fun onNewToken(token: String) {
        super.onNewToken(token)

        // Send token to backend server
        tokenManager.saveFcmToken(token)
        // TODO: Send to server via API
    }

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

        // Handle data payload
        message.data.isNotEmpty().let {
            handleDataMessage(message.data)
        }

        // Handle notification payload
        message.notification?.let {
            sendNotification(
                title = it.title ?: "New Message",
                body = it.body ?: "",
                data = message.data
            )
        }
    }

    private fun handleDataMessage(data: Map<String, String>) {
        val type = data["type"]
        when (type) {
            "new_post" -> {
                val postId = data["post_id"]?.toIntOrNull()
                postId?.let {
                    sendNotification(
                        title = "New Post",
                        body = data["title"] ?: "",
                        data = mapOf("post_id" to it.toString())
                    )
                }
            }
            "new_comment" -> {
                // Handle comment notification
            }
            "new_like" -> {
                // Handle like notification
            }
        }
    }

    private fun sendNotification(
        title: String,
        body: String,
        data: Map<String, String> = emptyMap()
    ) {
        val intent = Intent(this, MainActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
            data["post_id"]?.let {
                putExtra("post_id", it.toInt())
            }
        }

        val pendingIntent = PendingIntent.getActivity(
            this,
            0,
            intent,
            PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
        )

        val channelId = "default_channel"
        createNotificationChannel(channelId)

        val notification = NotificationCompat.Builder(this, channelId)
            .setSmallIcon(R.drawable.ic_notification)
            .setContentTitle(title)
            .setContentText(body)
            .setAutoCancel(true)
            .setContentIntent(pendingIntent)
            .setPriority(NotificationCompat.PRIORITY_HIGH)
            .build()

        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE)
            as NotificationManager
        notificationManager.notify(System.currentTimeMillis().toInt(), notification)
    }

    private fun createNotificationChannel(channelId: String) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel(
                channelId,
                "Default Notifications",
                NotificationManager.IMPORTANCE_HIGH
            ).apply {
                description = "Notifications for new posts and comments"
            }

            val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE)
                as NotificationManager
            notificationManager.createNotificationChannel(channel)
        }
    }
}