/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.hc.client5.http.impl.async;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.nio.ByteBuffer;
  import java.util.List;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.apache.hc.client5.http.async.AsyncExecCallback;
  import org.apache.hc.client5.http.async.AsyncExecChain;
  import org.apache.hc.client5.http.async.AsyncExecChainHandler;
  import org.apache.hc.client5.http.async.AsyncExecRuntime;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.Internal;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.concurrent.CancellableDependency;
  import org.apache.hc.core5.http.EntityDetails;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpException;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.message.RequestLine;
  import org.apache.hc.core5.http.nio.AsyncClientExchangeHandler;
  import org.apache.hc.core5.http.nio.AsyncDataConsumer;
  import org.apache.hc.core5.http.nio.AsyncEntityProducer;
  import org.apache.hc.core5.http.nio.CapacityChannel;
  import org.apache.hc.core5.http.nio.DataStreamChannel;
  import org.apache.hc.core5.http.nio.RequestChannel;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Usually the last HTTP/2 request execution handler in the asynchronous
   * request execution chain that is responsible for execution of
   * request / response exchanges with the opposite endpoint.
   *
   * @since 5.0
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  @Internal
  public class H2AsyncMainClientExec implements AsyncExecChainHandler {
  
      private static final Logger LOG = LoggerFactory.getLogger(H2AsyncMainClientExec.class);
  
      @Override
      public void execute(
              final HttpRequest request,
              final AsyncEntityProducer entityProducer,
              final AsyncExecChain.Scope scope,
              final AsyncExecChain chain,
              final AsyncExecCallback asyncExecCallback) throws HttpException, IOException {
          final String exchangeId = scope.exchangeId;
          final CancellableDependency operation = scope.cancellableDependency;
          final HttpClientContext clientContext = scope.clientContext;
          final AsyncExecRuntime execRuntime = scope.execRuntime;
  
          if (LOG.isDebugEnabled()) {
              LOG.debug("{} executing {}", exchangeId, new RequestLine(request));
          }
  
          final AsyncClientExchangeHandler internalExchangeHandler = new AsyncClientExchangeHandler() {
  
              private final AtomicReference<AsyncDataConsumer> entityConsumerRef = new AtomicReference<>();
  
              @Override
              public void releaseResources() {
                  final AsyncDataConsumer entityConsumer = entityConsumerRef.getAndSet(null);
                  if (entityConsumer != null) {
                      entityConsumer.releaseResources();
                  }
              }
 
             @Override
             public void failed(final Exception cause) {
                 final AsyncDataConsumer entityConsumer = entityConsumerRef.getAndSet(null);
                 if (entityConsumer != null) {
                     entityConsumer.releaseResources();
                 }
                 execRuntime.markConnectionNonReusable();
                 asyncExecCallback.failed(cause);
             }
 
             @Override
             public void cancel() {
                 failed(new InterruptedIOException());
             }
 
             @Override
             public void produceRequest(final RequestChannel channel, final HttpContext context) throws HttpException, IOException {
                 channel.sendRequest(request, entityProducer, context);
             }
 
             @Override
             public int available() {
                 return entityProducer.available();
             }
 
             @Override
             public void produce(final DataStreamChannel channel) throws IOException {
                 entityProducer.produce(channel);
             }
 
             @Override
             public void consumeInformation(final HttpResponse response, final HttpContext context) throws HttpException, IOException {
             }
 
             @Override
             public void consumeResponse(
                     final HttpResponse response,
                     final EntityDetails entityDetails,
                     final HttpContext context) throws HttpException, IOException {
                 entityConsumerRef.set(asyncExecCallback.handleResponse(response, entityDetails));
                 if (entityDetails == null) {
                     execRuntime.validateConnection();
                     asyncExecCallback.completed();
                 }
             }
 
             @Override
             public void updateCapacity(final CapacityChannel capacityChannel) throws IOException {
                 final AsyncDataConsumer entityConsumer = entityConsumerRef.get();
                 if (entityConsumer != null) {
                     entityConsumer.updateCapacity(capacityChannel);
                 } else {
                     capacityChannel.update(Integer.MAX_VALUE);
                 }
             }
 
             @Override
             public void consume(final ByteBuffer src) throws IOException {
                 final AsyncDataConsumer entityConsumer = entityConsumerRef.get();
                 if (entityConsumer != null) {
                     entityConsumer.consume(src);
                 }
             }
 
             @Override
             public void streamEnd(final List<? extends Header> trailers) throws HttpException, IOException {
                 final AsyncDataConsumer entityConsumer = entityConsumerRef.getAndSet(null);
                 if (entityConsumer != null) {
                     entityConsumer.streamEnd(trailers);
                 } else {
                     execRuntime.validateConnection();
                 }
                 asyncExecCallback.completed();
             }
 
         };
 
         if (LOG.isDebugEnabled()) {
             operation.setDependency(execRuntime.execute(
                     exchangeId,
                     new LoggingAsyncClientExchangeHandler(LOG, exchangeId, internalExchangeHandler),
                     clientContext));
         } else {
             operation.setDependency(execRuntime.execute(exchangeId, internalExchangeHandler, clientContext));
         }
     }
 
 }