Handling of multiple FirebaseMessagingService

FirebaseMessagingProxyService.kt

class FirebaseMessagingProxyService : FirebaseMessagingService() {

    private val messagingServices: List<FirebaseMessagingService> by lazy {
        listOf(FlutterFirebaseMessagingService())
                .onEach { it.injectContext(this) }
    }

    override fun onNewToken(token: String) {
        super.onNewToken(token)
        Log.d(TAG, "onNewToken: token")
        messagingServices.forEach { it.onNewToken(token) }
    }

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

        Log.d(TAG, "from: ${remoteMessage.from}")
        Log.d(TAG, "data: ${remoteMessage.data}")
        Log.d(TAG, "notification: ${remoteMessage.notification}")

        messagingServices.forEach { it.onMessageReceived(remoteMessage) }
    }

    override fun onDeletedMessages() {
        super.onDeletedMessages()
        Log.d(TAG, "onDeletedMessages")
        messagingServices.forEach { it.onDeletedMessages() }
    }

    override fun onMessageSent(message: String) {
        super.onMessageSent(message)
        Log.d(TAG, "onMessageSent: ${message}")
        messagingServices.forEach { it.onMessageSent(message) }
    }

    override fun onSendError(message: String, e: Exception) {
        super.onSendError(message, e)
        Log.d(TAG, "onSendError: ${message}", e)
        messagingServices.forEach { it.onSendError(message, e) }
    }
}

fun <T : Service> T.injectContext(context: T, func: T.() -> Unit = {}) {
    setField("mBase", context)
    func()
}

fun Class<*>.findDeclaredField(name: String): Field? {
    var clazz: Class<*>? = this
    do {
        try {
            return clazz?.getDeclaredField(name)
        } catch (e: Throwable) {}
        clazz = clazz?.superclass
    } while (clazz  != null)
    return null
}

fun Any.setField(name: String, value: Any): Boolean =
        javaClass.findDeclaredField(name)?.let {
            try {
                it.isAccessible = true
                it.set(this, value)
                true
            } catch (e: Throwable) { false }
        } ?: false

val Any.TAG: String
    get() {
        val tag = javaClass.simpleName
        val max = 23
        return if (tag.length <= max) tag else tag.substring(0, max)
    }