//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.client.util;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.util.Iterator;
  
  import org.eclipse.jetty.client.AsyncContentProvider;
  import org.eclipse.jetty.client.api.ContentProvider;
  import org.eclipse.jetty.client.api.Request;
  import org.eclipse.jetty.client.api.Response;
  import org.eclipse.jetty.util.Callback;
  
  /**
   * A {@link ContentProvider} that provides content asynchronously through an {@link OutputStream}
   * similar to {@link DeferredContentProvider}.
   * <p />
   * {@link OutputStreamContentProvider} can only be used in conjunction with
   * {@link Request#send(Response.CompleteListener)} (and not with its blocking counterpart {@link Request#send()})
   * because it provides content asynchronously.
   * <p />
   * The deferred content is provided once by writing to the {@link #getOutputStream() output stream}
   * and then fully consumed.
   * Invocations to the {@link #iterator()} method after the first will return an "empty" iterator
   * because the stream has been consumed on the first invocation.
   * However, it is possible for subclasses to support multiple invocations of {@link #iterator()}
   * by overriding {@link #write(ByteBuffer)} and {@link #close()}, copying the bytes and making them
   * available for subsequent invocations.
   * <p />
   * Content must be provided by writing to the {@link #getOutputStream() output stream}, that must be
   * {@link OutputStream#close() closed} when all content has been provided.
   * <p />
   * Example usage:
   * <pre>
   * HttpClient httpClient = ...;
   *
   * // Use try-with-resources to autoclose the output stream
   * OutputStreamContentProvider content = new OutputStreamContentProvider();
   * try (OutputStream output = content.getOutputStream())
   * {
   *     httpClient.newRequest("localhost", 8080)
   *             .content(content)
   *             .send(new Response.CompleteListener()
   *             {
   *                 &#64Override
   *                 public void onComplete(Result result)
   *                 {
   *                     // Your logic here
   *                 }
   *             });
   *
   *     // At a later time...
   *     output.write("some content".getBytes());
   * }
   * </pre>
   */
  public class OutputStreamContentProvider implements AsyncContentProvider, Callback, Closeable
  {
      private final DeferredContentProvider deferred = new DeferredContentProvider();
      private final OutputStream output = new DeferredOutputStream();
  
      @Override
      public long getLength()
      {
          return deferred.getLength();
      }
  
      @Override
      public Iterator<ByteBuffer> iterator()
      {
          return deferred.iterator();
      }
  
      @Override
      public void setListener(Listener listener)
      {
          deferred.setListener(listener);
      }
  
      public OutputStream getOutputStream()
     {
         return output;
     }
 
     protected void write(ByteBuffer buffer)
     {
         deferred.offer(buffer);
     }
 
     @Override
     public void close()
     {
         deferred.close();
     }
 
     @Override
     public void succeeded()
     {
         deferred.succeeded();
     }
 
     @Override
     public void failed(Throwable failure)
     {
         deferred.failed(failure);
     }
 
     private class DeferredOutputStream extends OutputStream
     {
         @Override
         public void write(int b) throws IOException
         {
             write(new byte[]{(byte)b}, 0, 1);
         }
 
         @Override
         public void write(byte[] b, int off, int len) throws IOException
         {
             OutputStreamContentProvider.this.write(ByteBuffer.wrap(b, off, len));
             flush();
         }
 
         @Override
         public void flush() throws IOException
         {
             deferred.flush();
         }
 
         @Override
         public void close() throws IOException
         {
             OutputStreamContentProvider.this.close();
         }
     }
 }