open class AsyncRoute<Request, Response> : Route<Request, Response>()
{
    /**
     * Channel provided by client application while building routes. This is how application listens for any
     * responses generated by its routes.
     */
    protected open lateinit var responseChannel: SendChannel<Response>
    /**
     * Listens for any responses generated by this route's controller, then if they pass
     * any tests provided by this route, passes them back to client.
     */
    protected open val listener = actor<Response>(CommonPool)
    {
        for (response in channel) this@AsyncRoute.attemptRespondSuspend(response)
    }

    override fun getControllerInstance(): Controller<Response>
    {
        return super.getControllerInstance().apply { (this as? AsyncController<Response>)?.listen(listener) }
    }

    open suspend fun attemptRespondSuspend(response: Response)
    {
        if (canRespond(response)) responseChannel.send(response)
    }

    override fun attemptRespond(response: Response)
    {
        launch(CommonPool) { attemptRespondSuspend(response) }
    }

    /**
     * In case of application shut down, this method should be called to clean this route's listener.
     */
    open fun close()
    {
        listener.cancel()
    }

    override fun attemptTrigger(request: Request)
    {
        if (canTrigger(request))
        {
            callback(this, request)
            getCurrentControllerInstance().getResponses().forEach(this::attemptRespond)
        }
        else
            getCurrentControllerInstance().getResponses() // used to clean out and discard any responses if they were generated
    }

    /**
     * Returns an empty list, since it isn't necessary anymore.
     */
    override fun getResponses(): List<Response>
    {
        return listOf()
    }
}