//
   //  ========================================================================
   //  Copyright (c) 1995-2014 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.http;
  
  import java.io.EOFException;
  import java.nio.ByteBuffer;
  
  import org.eclipse.jetty.client.HttpClient;
  import org.eclipse.jetty.client.HttpExchange;
  import org.eclipse.jetty.client.HttpReceiver;
  import org.eclipse.jetty.client.HttpResponse;
  import org.eclipse.jetty.client.HttpResponseException;
  import org.eclipse.jetty.http.HttpField;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.http.HttpParser;
  import org.eclipse.jetty.http.HttpVersion;
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.CompletableCallback;
  
  public class HttpReceiverOverHTTP extends HttpReceiver implements HttpParser.ResponseHandler<ByteBuffer>
  {
      private final HttpParser parser = new HttpParser(this);
      private ByteBuffer buffer;
      private boolean shutdown;
  
      public HttpReceiverOverHTTP(HttpChannelOverHTTP channel)
      {
          super(channel);
      }
  
      @Override
      public HttpChannelOverHTTP getHttpChannel()
      {
          return (HttpChannelOverHTTP)super.getHttpChannel();
      }
  
      private HttpConnectionOverHTTP getHttpConnection()
      {
          return getHttpChannel().getHttpConnection();
      }
  
      public void receive()
      {
          HttpClient client = getHttpDestination().getHttpClient();
          ByteBufferPool bufferPool = client.getByteBufferPool();
          buffer = bufferPool.acquire(client.getResponseBufferSize(), true);
          process();
      }
  
      private void process()
      {
          if (readAndParse())
          {
              HttpClient client = getHttpDestination().getHttpClient();
              ByteBufferPool bufferPool = client.getByteBufferPool();
              bufferPool.release(buffer);
              // Don't linger the buffer around if we are idle.
              buffer = null;
          }
      }
  
      private boolean readAndParse()
      {
          HttpConnectionOverHTTP connection = getHttpConnection();
          EndPoint endPoint = connection.getEndPoint();
          ByteBuffer buffer = this.buffer;
          while (true)
          {
              try
              {
                  // Connection may be closed in a parser callback.
                  if (connection.isClosed())
                  {
                      if (LOG.isDebugEnabled())
                          LOG.debug("{} closed", connection);
                      return true;
                  }
  
                  if (!parse(buffer))
                      return false;
  
                 int read = endPoint.fill(buffer);
                 // Avoid boxing of variable 'read'
                 if (LOG.isDebugEnabled())
                     LOG.debug("Read {} bytes from {}", read, endPoint);
 
                 if (read > 0)
                 {
                     if (!parse(buffer))
                         return false;
                 }
                 else if (read == 0)
                 {
                     fillInterested();
                     return true;
                 }
                 else
                 {
                     shutdown();
                     return true;
                 }
             }
             catch (Throwable x)
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug(x);
                 failAndClose(x);
                 return true;
             }
         }
     }
 
     /**
      * Parses a HTTP response from the given {@code buffer}.
      *
      * @param buffer the response bytes
      * @return true to indicate that the parsing may proceed (for example with another response),
      * false to indicate that the parsing should be interrupted (and will be resumed by another thread).
      */
     private boolean parse(ByteBuffer buffer)
     {
         // Must parse even if the buffer is fully consumed, to allow the
         // parser to advance from asynchronous content to response complete.
         if (parser.parseNext(buffer))
         {
             // If the parser returns true, we need to differentiate two cases:
             // A) the response is completed, so the parser is in START state;
             // B) the content is handled asynchronously, so the parser is in CONTENT state.
             return parser.isStart();
         }
         return true;
     }
 
     private void fillInterested()
     {
         getHttpChannel().getHttpConnection().fillInterested();
     }
 
     private void shutdown()
     {
         // Mark this receiver as shutdown, so that we can
         // close the connection when the exchange terminates.
         // We cannot close the connection from here because
         // the request may still be in process.
         shutdown = true;
 
         // Shutting down the parser may invoke messageComplete() or earlyEOF().
         // In case of content delimited by EOF, without a Connection: close
         // header, the connection will be closed at exchange termination
         // thanks to the flag we have set above.
         parser.atEOF();
         parser.parseNext(BufferUtil.EMPTY_BUFFER);
     }
 
     protected boolean isShutdown()
     {
         return shutdown;
     }
 
     @Override
     public int getHeaderCacheSize()
     {
         // TODO get from configuration
         return 256;
     }
 
     @Override
     public boolean startResponse(HttpVersion version, int status, String reason)
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         String method = exchange.getRequest().getMethod();
         parser.setHeadResponse(HttpMethod.HEAD.is(method) || HttpMethod.CONNECT.is(method));
         exchange.getResponse().version(version).status(status).reason(reason);
 
         responseBegin(exchange);
         return false;
     }
 
     @Override
     public boolean parsedHeader(HttpField field)
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         responseHeader(exchange, field);
         return false;
     }
 
     @Override
     public boolean headerComplete()
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         responseHeaders(exchange);
         return false;
     }
 
     @Override
     public boolean content(ByteBuffer buffer)
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         CompletableCallback callback = new CompletableCallback()
         {
             @Override
             public void resume()
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug("Content consumed asynchronously, resuming processing");
                 process();
             }
 
             public void abort(Throwable x)
             {
                 failAndClose(x);
             }
         };
         responseContent(exchange, buffer, callback);
         return callback.tryComplete();
     }
 
     @Override
     public boolean messageComplete()
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         responseSuccess(exchange);
         return true;
     }
 
     @Override
     public void earlyEOF()
     {
         HttpExchange exchange = getHttpExchange();
         HttpConnectionOverHTTP connection = getHttpConnection();
         if (exchange == null)
             connection.close();
         else
             failAndClose(new EOFException(String.valueOf(connection)));
     }
 
     @Override
     public void badMessage(int status, String reason)
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange != null)
         {
             HttpResponse response = exchange.getResponse();
             response.status(status).reason(reason);
             failAndClose(new HttpResponseException("HTTP protocol violation: bad response on " + getHttpConnection(), response));
         }
     }
 
     @Override
     protected void reset()
     {
         super.reset();
         parser.reset();
     }
 
     @Override
     protected void dispose()
     {
         super.dispose();
         parser.close();
     }
 
     private void failAndClose(Throwable failure)
     {
         if (responseFailure(failure))
             getHttpConnection().close(failure);
     }
 
     @Override
     public String toString()
     {
         return String.format("%s@%x on %s", getClass().getSimpleName(), hashCode(), getHttpConnection());
     }
 }