Notification Setup - Implement Basic FCM Service Setup (Part 1)

app/build.gradle.kts

@@ -116,6 +116,8 @@ dependencies {
     implementation(libs.google.id)
     // Firebase Analytics
     implementation(libs.firebase.analytics)
+    // Firebase Messaging
+    implementation(libs.firebase.messaging)
     // Coil Image Loading
     implementation(libs.coil.compose)
     implementation(libs.coil.network.okhttp)

app/src/main/AndroidManifest.xml

@@ -24,6 +24,13 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <service
+            android:name=".data.remote.HustleFirebaseMessagingService"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="com.google.firebase.MESSAGING_EVENT" />
+            </intent-filter>
+        </service>
     </application>
 
 </manifest>

app/src/main/java/com/cornellappdev/hustle/data/remote/HustleFirebaseMessagingService.kt

@@ -0,0 +1,98 @@
+package com.cornellappdev.hustle.data.remote
+
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.content.Intent
+import android.os.Build
+import androidx.core.app.NotificationCompat
+import com.cornellappdev.hustle.MainActivity
+import com.cornellappdev.hustle.R
+import com.cornellappdev.hustle.data.repository.FcmTokenRepository
+import com.google.firebase.messaging.FirebaseMessagingService
+import com.google.firebase.messaging.RemoteMessage
+import dagger.hilt.android.AndroidEntryPoint
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@AndroidEntryPoint
+class HustleFirebaseMessagingService : FirebaseMessagingService() {
+
+    @Inject
+    lateinit var fcmTokenRepository: FcmTokenRepository
+
+    @Inject
+    lateinit var applicationScope: CoroutineScope
+
+    private val notificationManager by lazy {
+        getSystemService(NOTIFICATION_SERVICE) as NotificationManager
+    }
+
+    override fun onCreate() {
+        super.onCreate()
+        createNotificationChannel()
+    }
+
+    override fun onNewToken(token: String) {
+        super.onNewToken(token)
+        applicationScope.launch {
+            fcmTokenRepository.updateFcmToken(token)
+        }
+    }
+
+    override fun onMessageReceived(message: RemoteMessage) {
+        super.onMessageReceived(message)
+        //TODO: Handle data messages for different notification types (eg. chat)
+        val title = message.notification?.title ?: message.data["title"] ?: "Hustle"
+        val body = message.notification?.body ?: message.data["body"] ?: ""
+
+        showNotification(title, body, message.data)
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                "Hustle Notifications",
+                NotificationManager.IMPORTANCE_HIGH
+            ).apply {
+                enableVibration(true)
+            }
+            notificationManager.createNotificationChannel(channel)
+        }
+    }
+
+    private fun showNotification(title: String, body: String, data: Map<String, String>) {
+        val intent = Intent(this, MainActivity::class.java).apply {
+            // new task for launching activity from service and clear top to avoid multiple activity instances
+            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TOP
+            data.forEach { (key, value) -> putExtra(key, value) }
+        }
+
+        // update current to ensure each notification has correct data and immutable for security best practices
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            data.hashCode(),
+            intent,
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        // TODO: Replace with actual app icon
+        val notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(title)
+            .setContentText(body)
+            .setSmallIcon(R.drawable.ic_google)
+            .setAutoCancel(true)
+            .setPriority(NotificationCompat.PRIORITY_HIGH)
+            .setContentIntent(pendingIntent)
+            .build()
+
+        notificationManager.notify(System.currentTimeMillis().toInt(), notification)
+    }
+
+    //TODO: Add more channels for different notification types
+    companion object {
+        private const val CHANNEL_ID = "hustle_notifications_general"
+    }
+}

app/src/main/java/com/cornellappdev/hustle/data/repository/FcmTokenRepository.kt

@@ -0,0 +1,26 @@
+package com.cornellappdev.hustle.data.repository
+
+import com.google.firebase.messaging.FirebaseMessaging
+import kotlinx.coroutines.tasks.await
+import javax.inject.Inject
+import javax.inject.Singleton
+
+interface FcmTokenRepository {
+    suspend fun getFcmToken(): Result<String>
+    suspend fun updateFcmToken(token: String): Result<Unit>
+}
+
+@Singleton
+class FcmTokenRepositoryImpl @Inject constructor(
+    private val firebaseMessaging: FirebaseMessaging,
+    // TODO: Add your API service to send token to backend
+) : FcmTokenRepository {
+
+    override suspend fun getFcmToken(): Result<String> = runCatching {
+        firebaseMessaging.token.await()
+    }
+
+    override suspend fun updateFcmToken(token: String): Result<Unit> = runCatching {
+        // TODO: Send token to backend
+    }
+}

app/src/main/java/com/cornellappdev/hustle/di/AppModule.kt

@@ -6,15 +6,21 @@ import com.cornellappdev.hustle.data.repository.AuthRepository
 import com.cornellappdev.hustle.data.repository.AuthRepositoryImpl
 import com.cornellappdev.hustle.data.repository.ExampleRepository
 import com.cornellappdev.hustle.data.repository.ExampleRepositoryImpl
+import com.cornellappdev.hustle.data.repository.FcmTokenRepository
+import com.cornellappdev.hustle.data.repository.FcmTokenRepositoryImpl
 import com.google.firebase.Firebase
 import com.google.firebase.auth.FirebaseAuth
 import com.google.firebase.auth.auth
+import com.google.firebase.messaging.FirebaseMessaging
 import dagger.Binds
 import dagger.Module
 import dagger.Provides
 import dagger.hilt.InstallIn
 import dagger.hilt.android.qualifiers.ApplicationContext
 import dagger.hilt.components.SingletonComponent
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
 import javax.inject.Singleton
 
 @Module
@@ -30,6 +36,12 @@ abstract class AppModule {
         authRepositoryImpl: AuthRepositoryImpl
     ): AuthRepository
 
+    @Binds
+    abstract fun bindFcmTokenRepository(
+        notificationRepositoryImpl: FcmTokenRepositoryImpl
+    ): FcmTokenRepository
+
+
     companion object {
         @Provides
         @Singleton
@@ -40,5 +52,17 @@ abstract class AppModule {
         fun provideCredentialManager(@ApplicationContext context: Context): CredentialManager {
             return CredentialManager.create(context)
         }
+
+        @Provides
+        @Singleton
+        fun provideFirebaseMessaging(): FirebaseMessaging {
+            return FirebaseMessaging.getInstance()
+        }
+
+        @Provides
+        @Singleton
+        fun provideApplicationScope(): CoroutineScope {
+            return CoroutineScope(SupervisorJob() + Dispatchers.IO)
+        }
     }
 }

gradle/libs.versions.toml

@@ -53,6 +53,7 @@ androidx-navigation-compose = { module = "androidx.navigation:navigation-compose
 firebase-bom = { group = "com.google.firebase", name = "firebase-bom", version.ref = "firebaseBom" }
 firebase-auth = { group = "com.google.firebase", name = "firebase-auth" }
 firebase-analytics = { group = "com.google.firebase", name = "firebase-analytics" }
+firebase-messaging = { group = "com.google.firebase", name = "firebase-messaging" }
 credential-manager = { group = "androidx.credentials", name = "credentials", version.ref = "credentialManager" }
 credential-manager-play-services = { group = "androidx.credentials", name = "credentials-play-services-auth", version.ref = "credentialManager" }
 google-id = { module = "com.google.android.libraries.identity.googleid:googleid", version.ref = "googleId" }