Revert "Remove half-baked FutureBaseChannel"

This reverts commit be15b68.

Author: ghostbuster91

modules/core/src/main/scala/jsonrpclib/internals/FutureBaseChannel.scala

@@ -0,0 +1,41 @@
+package jsonrpclib
+
+import jsonrpclib.internals._
+
+import java.util.concurrent.atomic.AtomicLong
+import scala.concurrent.ExecutionContext
+import scala.concurrent.Future
+import scala.concurrent.Promise
+import scala.util.Try
+
+abstract class FutureBasedChannel(endpoints: List[Endpoint[Future]])(implicit ec: ExecutionContext)
+    extends MessageDispatcher[Future] {
+
+  override def createPromise[A](callId: CallId): Future[(Try[A] => Future[Unit], () => Future[A])] = Future.successful {
+    val promise = Promise[A]()
+    val fulfill: Try[A] => Future[Unit] = (a: Try[A]) => Future.successful(promise.complete(a))
+    val future: () => Future[A] = () => promise.future
+    (fulfill, future)
+  }
+
+  protected def storePendingCall(callId: CallId, handle: OutputMessage => Future[Unit]): Future[Unit] =
+    Future.successful { val _ = pending.put(callId, handle) }
+  protected def removePendingCall(callId: CallId): Future[Option[OutputMessage => Future[Unit]]] =
+    Future.successful { Option(pending.remove(callId)) }
+  protected def getEndpoint(method: String): Future[Option[Endpoint[Future]]] =
+    Future.successful(endpointsMap.get(method))
+  protected def sendMessage(message: Message): Future[Unit] = {
+    sendPayload(Codec.encode(message)).map(_ => ())
+  }
+  protected def nextCallId(): Future[CallId] = Future.successful(CallId.NumberId(nextID.incrementAndGet()))
+
+  private[this] val endpointsMap: Map[String, Endpoint[Future]] = endpoints.map(ep => ep.method -> ep).toMap
+  private[this] val pending = new java.util.concurrent.ConcurrentHashMap[CallId, OutputMessage => Future[Unit]]
+  private[this] val nextID = new AtomicLong(0L)
+  // @volatile
+  // private[this] var closeReason: Throwable = _
+
+  def sendPayload(msg: Payload): Future[Unit] = ???
+  def reportError(params: Option[Payload], error: ProtocolError, method: String): Future[Unit] = ???
+
+}