//
   //  ========================================================================
   //  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.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.HttpStatus;
  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
  {
      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();
      }
  
      protected ByteBuffer getResponseBuffer()
      {
          return buffer;
      }
  
      public void receive()
      {
          if (buffer == null)
              acquireBuffer();
          process();
      }
  
      private void acquireBuffer()
      {
          HttpClient client = getHttpDestination().getHttpClient();
          ByteBufferPool bufferPool = client.getByteBufferPool();
          buffer = bufferPool.acquire(client.getResponseBufferSize(), true);
      }
  
      private void releaseBuffer()
      {
          if (buffer == null)
              throw new IllegalStateException();
          if (BufferUtil.hasContent(buffer))
              throw new IllegalStateException();
          HttpClient client = getHttpDestination().getHttpClient();
          ByteBufferPool bufferPool = client.getByteBufferPool();
          bufferPool.release(buffer);
          buffer = null;
      }
  
      private void process()
      {
          try
          {
              HttpConnectionOverHTTP connection = getHttpConnection();
              EndPoint endPoint = connection.getEndPoint();
              while (true)
              {
                 boolean upgraded = connection != endPoint.getConnection();
 
                 // Connection may be closed or upgraded in a parser callback.
                 if (connection.isClosed() || upgraded)
                 {
                     if (LOG.isDebugEnabled())
                         LOG.debug("{} {}", connection, upgraded ? "upgraded" : "closed");
                     releaseBuffer();
                     return;
                 }
 
                 if (parse())
                     return;
 
                 int read = endPoint.fill(buffer);
                 if (LOG.isDebugEnabled())
                     LOG.debug("Read {} bytes {} from {}", read, BufferUtil.toDetailString(buffer), endPoint);
 
                 if (read > 0)
                 {
                     if (parse())
                         return;
                 }
                 else if (read == 0)
                 {
                     releaseBuffer();
                     fillInterested();
                     return;
                 }
                 else
                 {
                     releaseBuffer();
                     shutdown();
                     return;
                 }
             }
         }
         catch (Throwable x)
         {
             if (LOG.isDebugEnabled())
                 LOG.debug(x);
             BufferUtil.clear(buffer);
             if (buffer != null)
                 releaseBuffer();
             failAndClose(x);
         }
     }
 
     /**
      * Parses a HTTP response in the receivers buffer.
      *
      * @return true to indicate that parsing should be interrupted (and will be resumed by another thread).
      */
     private boolean parse()
     {
         while (true)
         {
             // Must parse even if the buffer is fully consumed, to allow the
             // parser to advance from asynchronous content to response complete.
             boolean handle = parser.parseNext(buffer);
             if (LOG.isDebugEnabled())
                 LOG.debug("Parsed {}, remaining {} {}", handle, buffer.remaining(), parser);
             if (handle || !buffer.hasRemaining())
                 return handle;
         }
     }
 
     protected void fillInterested()
     {
         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);
 
         return !responseBegin(exchange);
     }
 
     @Override
     public void parsedHeader(HttpField field)
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return;
 
         responseHeader(exchange, field);
     }
 
     @Override
     public boolean headerComplete()
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         return !responseHeaders(exchange);
     }
 
     @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);
             }
         };
         // Do not short circuit these calls.
         boolean proceed = responseContent(exchange, buffer, callback);
         boolean async = callback.tryComplete();
         return !proceed || async;
     }
 
     @Override
     public boolean messageComplete()
     {
         HttpExchange exchange = getHttpExchange();
         if (exchange == null)
             return false;
 
         boolean proceed = responseSuccess(exchange);
         if (!proceed)
             return true;
 
         int status = exchange.getResponse().getStatus();
         if (status == HttpStatus.SWITCHING_PROTOCOLS_101)
             return true;
 
         if (HttpMethod.CONNECT.is(exchange.getRequest().getMethod()) &&
                 status == HttpStatus.OK_200)
             return true;
 
         return false;
     }
 
     @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[%s]", super.toString(), parser);
     }
 }