/*
    * ====================================================================
    * 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.http.nio.entity;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteBuffer;
  import java.nio.channels.Channels;
  import java.nio.channels.ReadableByteChannel;
  
  import org.apache.http.HttpEntity;
  import org.apache.http.nio.ContentEncoder;
  import org.apache.http.nio.IOControl;
  import org.apache.http.util.Args;
  
  /**
   * Basic implementation of {@link HttpAsyncContentProducer} that relies on
   * inefficient and potentially blocking I/O operation redirection through
   * {@link Channels#newChannel(java.io.InputStream)}.
   *
   * @since 4.2
   */
  public class EntityAsyncContentProducer implements HttpAsyncContentProducer {
  
      private final HttpEntity entity;
      private final ByteBuffer buffer;
      private ReadableByteChannel channel;
  
      public EntityAsyncContentProducer(final HttpEntity entity) {
          super();
          Args.notNull(entity, "HTTP entity");
          this.entity = entity;
          this.buffer = ByteBuffer.allocate(4096);
      }
  
      @Override
      public void produceContent(
              final ContentEncoder encoder, final IOControl ioControl) throws IOException {
          if (this.channel == null) {
              this.channel = Channels.newChannel(this.entity.getContent());
          }
          final int i = this.channel.read(this.buffer);
          this.buffer.flip();
          encoder.write(this.buffer);
          final boolean buffering = this.buffer.hasRemaining();
          this.buffer.compact();
          if (i == -1 && !buffering) {
              encoder.complete();
              close();
          }
      }
  
      @Override
      public boolean isRepeatable() {
          return this.entity.isRepeatable();
      }
  
      @Override
      public void close() throws IOException {
          final ReadableByteChannel local = this.channel;
          this.channel = null;
          if (local != null) {
              local.close();
          }
          if (this.entity.isStreaming()) {
              final InputStream inStream = this.entity.getContent();
              inStream.close();
          }
      }
  
      @Override
      public String toString() {
          return this.entity.toString();
      }
 
 }