add messaging functionality

Author: Bas Buijsen

firebase-messaging/src/androidMain/kotlin/dev/gitlive/firebase/messaging/messaging.kt

@@ -2,10 +2,19 @@
 package dev.gitlive.firebase.messaging
 
 import dev.gitlive.firebase.Firebase
+import kotlinx.coroutines.tasks.await
 
 actual val Firebase.messaging: FirebaseMessaging
     get() = FirebaseMessaging(com.google.firebase.messaging.FirebaseMessaging.getInstance())
 
 actual class FirebaseMessaging(val android: com.google.firebase.messaging.FirebaseMessaging) {
+    actual fun subscribeToTopic(topic: String) {
+        android.subscribeToTopic(topic)
+    }
 
+    actual fun unsubscribeFromTopic(topic: String) {
+        android.unsubscribeFromTopic(topic)
+    }
+
+    actual suspend fun getToken(): String = android.token.await()
 }

firebase-messaging/src/commonMain/kotlin/dev/gitlive/firebase/messaging/messaging.kt

@@ -6,4 +6,22 @@ import dev.gitlive.firebase.FirebaseApp
 /** Returns the [FirebaseMessaging] instance of the default [FirebaseApp]. */
 expect val Firebase.messaging: FirebaseMessaging
 
-expect class FirebaseMessaging
+expect class FirebaseMessaging {
+    /**
+     * Subscribe to a topic.
+     * @param topic The topic to subscribe to.
+     */
+    fun subscribeToTopic(topic: String)
+
+    /**
+     * Unsubscribe from a topic.
+     * @param topic The topic to unsubscribe from.
+     */
+    fun unsubscribeFromTopic(topic: String)
+
+    /**
+     * Get FCM token for client
+     * @return [String] FCM token
+     */
+    suspend fun getToken(): String
+}

firebase-messaging/src/iosMain/kotlin/dev/gitlive/firebase/messaging/messaging.kt

@@ -2,10 +2,44 @@ package dev.gitlive.firebase.messaging
 
 import cocoapods.FirebaseMessaging.FIRMessaging
 import dev.gitlive.firebase.Firebase
+import kotlinx.coroutines.CompletableDeferred
+import platform.Foundation.NSError
 
 actual val Firebase.messaging: FirebaseMessaging
     get() = FirebaseMessaging(FIRMessaging.messaging())
 
 actual class FirebaseMessaging(val ios: FIRMessaging) {
+    actual fun subscribeToTopic(topic: String) {
+        ios.subscribeToTopic(topic)
+    }
 
+    actual fun unsubscribeFromTopic(topic: String) {
+        ios.unsubscribeFromTopic(topic)
+    }
+
+    actual suspend fun getToken(): String = awaitResult { ios.tokenWithCompletion(it) }
+}
+
+suspend inline fun <T> T.await(function: T.(callback: (NSError?) -> Unit) -> Unit) {
+    val job = CompletableDeferred<Unit>()
+    function { error ->
+        if(error == null) {
+            job.complete(Unit)
+        } else {
+            job.completeExceptionally(Exception(error.toString()))
+        }
+    }
+    job.await()
+}
+
+suspend inline fun <T, reified R> T.awaitResult(function: T.(callback: (R?, NSError?) -> Unit) -> Unit): R {
+    val job = CompletableDeferred<R?>()
+    function { result, error ->
+        if(error == null) {
+            job.complete(result)
+        } else {
+            job.completeExceptionally(Exception(error.toString()))
+        }
+    }
+    return job.await() as R
 }

firebase-messaging/src/jsMain/kotlin/dev/gitlive/firebase/messaging/externals/messaging.kt

@@ -1,9 +1,15 @@
 package dev.gitlive.firebase.messaging.externals
 
 import dev.gitlive.firebase.externals.FirebaseApp
+import kotlin.js.Promise
 
 external fun getMessaging(
     app: FirebaseApp? = definedExternally,
 ): Messaging
 
-external interface Messaging
+external fun getToken(messaging: Messaging = definedExternally, options: dynamic = definedExternally): Promise<String>
+
+external interface Messaging {
+    fun subscribeToTopic(tokens: Array<String>, topic: String): Promise<Unit>
+    fun unsubscribeFromTopic(tokens: Array<String>, topic: String): Promise<Unit>
+}

firebase-messaging/src/jsMain/kotlin/dev/gitlive/firebase/messaging/messaging.kt

@@ -3,10 +3,25 @@ package dev.gitlive.firebase.messaging
 import dev.gitlive.firebase.Firebase
 import dev.gitlive.firebase.messaging.externals.Messaging
 import dev.gitlive.firebase.messaging.externals.getMessaging
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.await
+import kotlinx.coroutines.launch
 
 actual val Firebase.messaging: FirebaseMessaging
     get() = FirebaseMessaging(getMessaging())
 
 actual class FirebaseMessaging(val js: Messaging) {
+    actual fun subscribeToTopic(topic: String) {
+        GlobalScope.launch {
+            js.subscribeToTopic(arrayOf(getToken()), topic)
+        }
+    }
 
+    actual fun unsubscribeFromTopic(topic: String) {
+        GlobalScope.launch {
+            js.unsubscribeFromTopic(arrayOf(getToken()), topic)
+        }
+    }
+
+    actual suspend fun getToken(): String = dev.gitlive.firebase.messaging.externals.getToken(js).await()
 }

firebase-messaging/src/jvmMain/kotlin/dev/gitlive/firebase/messaging/messaging.kt

@@ -6,4 +6,16 @@ import dev.gitlive.firebase.Firebase
 actual val Firebase.messaging: FirebaseMessaging
     get() = TODO("Not yet implemented")
 
-actual class FirebaseMessaging
+actual class FirebaseMessaging {
+    actual fun subscribeToTopic(topic: String) {
+        TODO("Not yet implemented")
+    }
+
+    actual fun unsubscribeFromTopic(topic: String) {
+        TODO("Not yet implemented")
+    }
+
+    actual suspend fun getToken(): String {
+        TODO("Not yet implemented")
+    }
+}