/*
    * ====================================================================
    * 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.testing.async;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.List;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.apache.hc.core5.concurrent.FutureCallback;
  import org.apache.hc.core5.http.ContentType;
  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.HttpStatus;
  import org.apache.hc.core5.http.MethodNotSupportedException;
  import org.apache.hc.core5.http.message.BasicHttpResponse;
  import org.apache.hc.core5.http.nio.AsyncEntityProducer;
  import org.apache.hc.core5.http.nio.AsyncServerExchangeHandler;
  import org.apache.hc.core5.http.nio.CapacityChannel;
  import org.apache.hc.core5.http.nio.DataStreamChannel;
  import org.apache.hc.core5.http.nio.ResponseChannel;
  import org.apache.hc.core5.http.nio.entity.BasicAsyncEntityConsumer;
  import org.apache.hc.core5.http.nio.entity.BasicAsyncEntityProducer;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Asserts;
  
  /**
   * A handler that echos the incoming request entity.
   */
  public class AsyncEchoHandler implements AsyncServerExchangeHandler {
  
      private final BasicAsyncEntityConsumer entityConsumer;
      private final AtomicReference<AsyncEntityProducer> entityProducerRef;
  
      public AsyncEchoHandler() {
          this.entityConsumer = new BasicAsyncEntityConsumer();
          this.entityProducerRef = new AtomicReference<>();
      }
  
      @Override
      public void releaseResources() {
          entityConsumer.releaseResources();
          final AsyncEntityProducer producer = entityProducerRef.getAndSet(null);
          if (producer != null) {
              producer.releaseResources();
          }
      }
  
      @Override
      public void handleRequest(
              final HttpRequest request,
              final EntityDetails entityDetails,
              final ResponseChannel responseChannel,
              final HttpContext context) throws HttpException, IOException {
          final String method = request.getMethod();
          if (!"GET".equalsIgnoreCase(method) &&
                  !"HEAD".equalsIgnoreCase(method) &&
                  !"POST".equalsIgnoreCase(method) &&
                  !"PUT".equalsIgnoreCase(method)) {
              throw new MethodNotSupportedException(method + " not supported by " + getClass().getName());
          }
          if (entityDetails != null) {
  
              final ContentType contentType = ContentType.parseLenient(entityDetails.getContentType());
              entityConsumer.streamStart(entityDetails, new FutureCallback<byte[]>() {
  
                  @Override
                  public void completed(final byte[] content) {
                      final BasicAsyncEntityProducer entityProducer = new BasicAsyncEntityProducer(content, contentType);
                      entityProducerRef.set(entityProducer);
                      try {
                          responseChannel.sendResponse(new BasicHttpResponse(HttpStatus.SC_OK), entityProducer, context);
                     } catch (final IOException | HttpException ex) {
                         failed(ex);
                     }
                 }
 
                 @Override
                 public void failed(final Exception ex) {
                     releaseResources();
                 }
 
                 @Override
                 public void cancelled() {
                     releaseResources();
                 }
 
             });
         } else {
             responseChannel.sendResponse(new BasicHttpResponse(HttpStatus.SC_OK), null, context);
             entityConsumer.releaseResources();
         }
     }
 
     @Override
     public void updateCapacity(final CapacityChannel capacityChannel) throws IOException {
         entityConsumer.updateCapacity(capacityChannel);
     }
 
     @Override
     public void consume(final ByteBuffer src) throws IOException {
         entityConsumer.consume(src);
     }
 
     @Override
     public void streamEnd(final List<? extends Header> trailers) throws HttpException, IOException {
         entityConsumer.streamEnd(trailers);
     }
 
     @Override
     public int available() {
         final AsyncEntityProducer producer = entityProducerRef.get();
         Asserts.notNull(producer, "Entity producer");
         return producer.available();
     }
 
     @Override
     public void produce(final DataStreamChannel channel) throws IOException {
         final AsyncEntityProducer producer = entityProducerRef.get();
         Asserts.notNull(producer, "Entity producer");
         producer.produce(channel);
     }
 
     @Override
     public void failed(final Exception cause) {
         releaseResources();
     }
 
 }