text: /*
   * Copyright 2018-present HiveMQ and the HiveMQ Community
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.hivemq.client.internal.mqtt.handler.publish.outgoing;
  
  import com.hivemq.client.internal.annotations.CallByThread;
  import com.hivemq.client.internal.mqtt.MqttClientConfig;
  import com.hivemq.client.internal.mqtt.exceptions.MqttClientStateExceptions;
  import com.hivemq.client.internal.mqtt.ioc.ClientComponent;
  import com.hivemq.client.internal.mqtt.message.publish.MqttPublish;
  import com.hivemq.client.internal.mqtt.message.publish.MqttPublishResult;
  import com.hivemq.client.mqtt.mqtt5.message.publish.Mqtt5PublishResult;
  import io.reactivex.Flowable;
  import io.reactivex.Single;
  import io.reactivex.SingleObserver;
  import io.reactivex.disposables.Disposable;
  import io.reactivex.internal.disposables.EmptyDisposable;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  
  /**
   * @author Silvio Giebl
   */
  public class MqttAckSingle extends Single<Mqtt5PublishResult> {
  
      private final @NotNull MqttClientConfig clientConfig;
      private final @NotNull MqttPublish publish;
  
      public MqttAckSingle(final @NotNull MqttClientConfig clientConfig, final @NotNull MqttPublish publish) {
          this.clientConfig = clientConfig;
          this.publish = publish;
      }
  
      @Override
      protected void subscribeActual(final @NotNull SingleObserver<? super Mqtt5PublishResult> observer) {
          if (clientConfig.getState().isConnectedOrReconnect()) {
              final ClientComponent clientComponent = clientConfig.getClientComponent();
              final MqttOutgoingQosHandler outgoingQosHandler = clientComponent.outgoingQosHandler();
              final MqttPublishFlowables publishFlowables = outgoingQosHandler.getPublishFlowables();
  
              final Flow flow = new Flow(observer, clientConfig, outgoingQosHandler);
              observer.onSubscribe(flow);
              publishFlowables.add(Flowable.just(new MqttPublishWithFlow(publish, flow)));
          } else {
              EmptyDisposable.error(MqttClientStateExceptions.notConnected(), observer);
          }
      }
  
      private static class Flow extends MqttAckFlow implements Disposable {
  
          private final @NotNull SingleObserver<? super Mqtt5PublishResult> observer;
          private final @NotNull MqttOutgoingQosHandler outgoingQosHandler;
  
          private @Nullable MqttPublishResult result;
  
          Flow(
                  final @NotNull SingleObserver<? super Mqtt5PublishResult> observer,
                  final @NotNull MqttClientConfig clientConfig,
                  final @NotNull MqttOutgoingQosHandler outgoingQosHandler) {
  
              super(clientConfig);
              this.observer = observer;
              this.outgoingQosHandler = outgoingQosHandler;
              init();
          }
  
          @CallByThread("Netty EventLoop")
          @Override
          void onNext(final @NotNull MqttPublishResult result) {
              if (result.acknowledged()) {
                  done(result);
              } else {
                  this.result = result;
              }
          }
  
          @CallByThread("Netty EventLoop")
          @Override
          void acknowledged(final long acknowledged) {
              final MqttPublishResult result = this.result;
              assert (acknowledged == 1) && (result != null) : "a single publish must be acknowledged exactly once";
              this.result = null;
              done(result);
          }
  
          @CallByThread("Netty EventLoop")
          private void done(final @NotNull MqttPublishResult result) {
              if (setDone()) {
                  final Throwable error = result.getRawError();
                  if (error == null) {
                      observer.onSuccess(result);
                  } else {
                      observer.onError(error);
                  }
              }
              outgoingQosHandler.request(1);
          }
      }
  }
  