//
   //  ========================================================================
   //  Copyright (c) 1995-2013 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.server;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.ClosedChannelException;
  import java.util.concurrent.RejectedExecutionException;
  
  import org.eclipse.jetty.http.HttpGenerator;
  import org.eclipse.jetty.http.HttpGenerator.ResponseInfo;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpHeaderValue;
  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.AbstractConnection;
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.io.Connection;
  import org.eclipse.jetty.io.EndPoint;
  import org.eclipse.jetty.io.EofException;
  import org.eclipse.jetty.util.BlockingCallback;
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.Callback;
  import org.eclipse.jetty.util.IteratingCallback;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  /**
   * <p>A {@link Connection} that handles the HTTP protocol.</p>
   */
  public class HttpConnection extends AbstractConnection implements Runnable, HttpTransport
  {
      public static final String UPGRADE_CONNECTION_ATTRIBUTE = "org.eclipse.jetty.server.HttpConnection.UPGRADE";
      private static final boolean REQUEST_BUFFER_DIRECT=false;
      private static final boolean HEADER_BUFFER_DIRECT=false;
      private static final boolean CHUNK_BUFFER_DIRECT=false;
      private static final Logger LOG = Log.getLogger(HttpConnection.class);
      private static final ThreadLocal<HttpConnection> __currentConnection = new ThreadLocal<>();
  
      private final HttpConfiguration _config;
      private final Connector _connector;
      private final ByteBufferPool _bufferPool;
      private final HttpGenerator _generator;
      private final HttpChannelOverHttp _channel;
      private final HttpParser _parser;
      private volatile ByteBuffer _requestBuffer = null;
      private volatile ByteBuffer _chunk = null;
      private BlockingCallback _readBlocker = new BlockingCallback();
      private BlockingCallback _writeBlocker = new BlockingCallback();
  
  
      public static HttpConnection getCurrentConnection()
      {
          return __currentConnection.get();
      }
  
      protected static void setCurrentConnection(HttpConnection connection)
      {
          __currentConnection.set(connection);
      }
  
      public HttpConfiguration getHttpConfiguration()
      {
          return _config;
      }
  
      public HttpConnection(HttpConfiguration config, Connector connector, EndPoint endPoint)
      {
          // Tell AbstractConnector executeOnFillable==true because we want the same thread that
          // does the HTTP parsing to handle the request so its cache is hot
          super(endPoint, connector.getExecutor(),true);
  
          _config = config;
          _connector = connector;
          _bufferPool = _connector.getByteBufferPool();
          _generator = new HttpGenerator(_config.getSendServerVersion(),_config.getSendXPoweredBy());
          _channel = new HttpChannelOverHttp(connector, config, endPoint, this, new Input());
          _parser = newHttpParser();
  
          LOG.debug("New HTTP Connection {}", this);
      }
 
     protected HttpParser newHttpParser()
     {
         return new HttpParser(newRequestHandler(), getHttpConfiguration().getRequestHeaderSize());
     }
 
     protected HttpParser.RequestHandler<ByteBuffer> newRequestHandler()
     {
         return _channel;
     }
 
     public Server getServer()
     {
         return _connector.getServer();
     }
 
     public Connector getConnector()
     {
         return _connector;
     }
 
     public HttpChannel<?> getHttpChannel()
     {
         return _channel;
     }
 
     public void reset()
     {
         // If we are still expecting
         if (_channel.isExpecting100Continue())
         {
             // reset to avoid seeking remaining content
             _parser.reset();
             // close to seek EOF
             _parser.close();
             if (getEndPoint().isOpen())
                 fillInterested();
         }
         // else if we are persistent
         else if (_generator.isPersistent())
             // reset to seek next request
             _parser.reset();
         else
         {
             // else seek EOF
             _parser.close();
             if (getEndPoint().isOpen())
                 fillInterested();
         }
 
         _generator.reset();
         _channel.reset();
 
         releaseRequestBuffer();
         if (_chunk!=null)
         {
             _bufferPool.release(_chunk);
             _chunk=null;
         }
     }
 
 
     @Override
     public int getMessagesIn()
     {
         return getHttpChannel().getRequests();
     }
 
     @Override
     public int getMessagesOut()
     {
         return getHttpChannel().getRequests();
     }
 
     @Override
     public String toString()
     {
         return String.format("%s,g=%s,p=%s",
                 super.toString(),
                 _generator,
                 _parser);
     }
 
     private void releaseRequestBuffer()
     {
         if (_requestBuffer != null && !_requestBuffer.hasRemaining())
         {
             ByteBuffer buffer=_requestBuffer;
             _requestBuffer=null;
             _bufferPool.release(buffer);
         }
     }
 
     /**
      * <p>Parses and handles HTTP messages.</p>
      * <p>This method is called when this {@link Connection} is ready to read bytes from the {@link EndPoint}.
      * However, it can also be called if there is unconsumed data in the _requestBuffer, as a result of
      * resuming a suspended request when there is a pipelined request already read into the buffer.</p>
      * <p>This method fills bytes and parses them until either: EOF is filled; 0 bytes are filled;
      * the HttpChannel finishes handling; or the connection has changed.</p>
      */
     @Override
     public void onFillable()
     {
         LOG.debug("{} onFillable {}", this, _channel.getState());
 
         setCurrentConnection(this);
         try
         {
             while (true)
             {
                 // Can the parser progress (even with an empty buffer)
                 boolean call_channel=_parser.parseNext(_requestBuffer==null?BufferUtil.EMPTY_BUFFER:_requestBuffer);
 
                 // Parse the buffer
                 if (call_channel)
                 {
                     // Parse as much content as there is available before calling the channel
                     // this is both efficient (may queue many chunks), will correctly set available for 100 continues
                     // and will drive the parser to completion if all content is available.
                     while (_parser.inContentState())
                     {
                         if (!_parser.parseNext(_requestBuffer==null?BufferUtil.EMPTY_BUFFER:_requestBuffer))
                             break;
                     }
 
                     // The parser returned true, which indicates the channel is ready to handle a request.
                     // Call the channel and this will either handle the request/response to completion OR,
                     // if the request suspends, the request/response will be incomplete so the outer loop will exit.
                     boolean handle=_channel.handle();
 
                     // Return if suspended or upgraded
                     if (!handle || getEndPoint().getConnection()!=this)
                         return;
                 }
                 else if (BufferUtil.isEmpty(_requestBuffer))
                 {
                     if (_requestBuffer == null)
                         _requestBuffer = _bufferPool.acquire(getInputBufferSize(), REQUEST_BUFFER_DIRECT);
 
                     int filled = getEndPoint().fill(_requestBuffer);
                     if (filled==0) // Do a retry on fill 0 (optimisation for SSL connections)
                         filled = getEndPoint().fill(_requestBuffer);
                     
                     LOG.debug("{} filled {}", this, filled);
 
                     // If we failed to fill
                     if (filled == 0)
                     {
                         // Somebody wanted to read, we didn't so schedule another attempt
                         releaseRequestBuffer();
                         fillInterested();
                         return;
                     }
                     else if (filled < 0)
                     {
                         _parser.shutdownInput();
                         // We were only filling if fully consumed, so if we have
                         // read -1 then we have nothing to parse and thus nothing that
                         // will generate a response.  If we had a suspended request pending
                         // a response or a request waiting in the buffer, we would not be here.
                         if (getEndPoint().isOutputShutdown())
                             getEndPoint().close();
                         else
                             getEndPoint().shutdownOutput();
                         // buffer must be empty and the channel must be idle, so we can release.
                         releaseRequestBuffer();
                         return;
                     }
                 }
                 else
                 {
                     // TODO work out how we can get here and a better way to handle it
                     LOG.warn("Unexpected state: "+this+ " "+_channel+" "+_channel.getRequest());
                     if (!_channel.getState().isSuspended())
                         getEndPoint().close();
                     return;
                 }
             }
         }
         catch (EofException e)
         {
             LOG.debug(e);
         }
         catch (Exception e)
         {
             if (_parser.isIdle())
                 LOG.debug(e);
             else
                 LOG.warn(this.toString(), e);
             close();
         }
         finally
         {
             setCurrentConnection(null);
         }
     }
 
     @Override
     public void onOpen()
     {
         super.onOpen();
         fillInterested();
     }
 
     @Override
     public void run()
     {
         onFillable();
     }
 
     @Override
     public void send(HttpGenerator.ResponseInfo info, ByteBuffer content, boolean lastContent) throws IOException
     {
         try
         {
             if (info==null)
                 new ContentCallback(content,lastContent,_writeBlocker).iterate();
             else
             {
                 // If we are still expecting a 100 continues
                 if (_channel.isExpecting100Continue())
                     // then we can't be persistent
                     _generator.setPersistent(false);
                 new CommitCallback(info,content,lastContent,_writeBlocker).iterate();
             }
             _writeBlocker.block();
         }
         catch (ClosedChannelException e)
         {
             throw new EofException(e);
         }
         catch (IOException e)
         {
             throw e;
         }
     }
 
     @Override
     public void send(ResponseInfo info, ByteBuffer content, boolean lastContent, Callback callback)
     {
         if (info==null)
             new ContentCallback(content,lastContent,callback).iterate();
         else
         {
             // If we are still expecting a 100 continues
             if (_channel.isExpecting100Continue())
                 // then we can't be persistent
                 _generator.setPersistent(false);
             new CommitCallback(info,content,lastContent,callback).iterate();
         }
     }
 
     @Override
     public void send(ByteBuffer content, boolean lastContent, Callback callback)
     {
         new ContentCallback(content,lastContent,callback).iterate();
     }
 
     @Override
     public void completed()
     {
         // Finish consuming the request
         if (_parser.isInContent() && _generator.isPersistent() && !_channel.isExpecting100Continue())
             // Complete reading the request
             _channel.getRequest().getHttpInput().consumeAll();
 
         // Handle connection upgrades
         if (_channel.getResponse().getStatus() == HttpStatus.SWITCHING_PROTOCOLS_101)
         {
             Connection connection = (Connection)_channel.getRequest().getAttribute(UPGRADE_CONNECTION_ATTRIBUTE);
             if (connection != null)
             {
                 LOG.debug("Upgrade from {} to {}", this, connection);
                 onClose();
                 getEndPoint().setConnection(connection);
                 connection.onOpen();
                 reset();
                 return;
             }
         }
 
         reset();
 
         // if we are not called from the onfillable thread, schedule completion
         if (getCurrentConnection()!=this)
         {
             if (_parser.isStart())
             {
                 // it wants to eat more
                 if (_requestBuffer == null)
                 {
                     fillInterested();
                 }
                 else if (getConnector().isStarted())
                 {
                     LOG.debug("{} pipelined", this);
 
                     try
                     {
                         getExecutor().execute(this);
                     }
                     catch (RejectedExecutionException e)
                     {
                         if (getConnector().isStarted())
                             LOG.warn(e);
                         else
                             LOG.ignore(e);
                         getEndPoint().close();
                     }
                 }
                 else
                 {
                     getEndPoint().close();
                 }
             }
         }
     }
 
     public ByteBuffer getRequestBuffer()
     {
         return _requestBuffer;
     }
 
     private class Input extends ByteBufferHttpInput
     {
         @Override
         protected void blockForContent() throws IOException
         {
             /* We extend the blockForContent method to replace the
             default implementation of a blocking queue with an implementation
             that uses the calling thread to block on a readable callback and
             then to do the parsing before before attempting the read.
              */
             while (!_parser.isComplete())
             {
                 // Can the parser progress (even with an empty buffer)
                 boolean event=_parser.parseNext(_requestBuffer==null?BufferUtil.EMPTY_BUFFER:_requestBuffer);
 
                 // If there is more content to parse, loop so we can queue all content from this buffer now without the
                 // need to call blockForContent again
                 while (!event && BufferUtil.hasContent(_requestBuffer) && _parser.inContentState())
                     event=_parser.parseNext(_requestBuffer);
 
                 // If we have content, return
                 if (_parser.isComplete() || available()>0)
                     return;
 
                 // Do we have content ready to parse?
                 if (BufferUtil.isEmpty(_requestBuffer))
                 {
                     // If no more input
                     if (getEndPoint().isInputShutdown())
                     {
                         _parser.shutdownInput();
                         shutdown();
                         return;
                     }
 
                     // Wait until we can read
                     block(_readBlocker);
                     LOG.debug("{} block readable on {}",this,_readBlocker);
                     _readBlocker.block();
 
                     // We will need a buffer to read into
                     if (_requestBuffer==null)
                     {
                         long content_length=_channel.getRequest().getContentLength();
                         int size=getInputBufferSize();
                         if (size<content_length)
                             size=size*4; // TODO tune this
                         _requestBuffer=_bufferPool.acquire(size,REQUEST_BUFFER_DIRECT);
                     }
 
                     // read some data
                     int filled=getEndPoint().fill(_requestBuffer);
                     LOG.debug("{} block filled {}",this,filled);
                     if (filled<0)
                     {
                         _parser.shutdownInput();
                         return;
                     }
                 }
             }
         }
 
         @Override
         protected void onContentQueued(ByteBuffer ref)
         {
             /* This callback could be used to tell the connection
              * that the request did contain content and thus the request
              * buffer needs to be held until a call to #onAllContentConsumed
              *
              * However it turns out that nothing is needed here because either a
              * request will have content, in which case the request buffer will be
              * released by a call to onAllContentConsumed; or it will not have content.
              * If it does not have content, either it will complete quickly and the
              * buffers will be released in completed() or it will be suspended and
              * onReadable() contains explicit handling to release if it is suspended.
              *
              * We extend this method anyway, to turn off the notify done by the
              * default implementation as this is not needed by our implementation
              * of blockForContent
              */
         }
 
         @Override
         public void earlyEOF()
         {
             synchronized (lock())
             {
                 _inputEOF=true;
                 _earlyEOF = true;
                 LOG.debug("{} early EOF", this);
             }
         }
 
         @Override
         public void shutdown()
         {
             synchronized (lock())
             {
                 _inputEOF=true;
                 LOG.debug("{} shutdown", this);
             }
         }
         
         @Override
         protected void onAllContentConsumed()
         {
             /* This callback tells the connection that all content that has
              * been parsed has been consumed. Thus the request buffer may be
              * released if it is empty.
              */
             releaseRequestBuffer();
         }
 
         @Override
         public String toString()
         {
             return super.toString()+"{"+_channel+","+HttpConnection.this+"}";
         }
     }
 
     private class HttpChannelOverHttp extends HttpChannel<ByteBuffer>
     {
         public HttpChannelOverHttp(Connector connector, HttpConfiguration config, EndPoint endPoint, HttpTransport transport, HttpInput<ByteBuffer> input)
         {
             super(connector,config,endPoint,transport,input);
         }
 
         @Override
         public void badMessage(int status, String reason)
         {
             _generator.setPersistent(false);
             super.badMessage(status,reason);
         }
 
         @Override
         public boolean headerComplete()
         {
             boolean persistent;
             HttpVersion version = getHttpVersion();
 
             switch (version)
             {
                 case HTTP_0_9:
                 {
                     persistent = false;
                     break;
                 }
                 case HTTP_1_0:
                 {
                     persistent = getRequest().getHttpFields().contains(HttpHeader.CONNECTION, HttpHeaderValue.KEEP_ALIVE.asString());
                     if (!persistent)
                         persistent = HttpMethod.CONNECT.is(getRequest().getMethod());
                     if (persistent)
                         getResponse().getHttpFields().add(HttpHeader.CONNECTION, HttpHeaderValue.KEEP_ALIVE);
                     break;
                 }
                 case HTTP_1_1:
                 {
                     persistent = !getRequest().getHttpFields().contains(HttpHeader.CONNECTION, HttpHeaderValue.CLOSE.asString());
                     if (!persistent)
                         persistent = HttpMethod.CONNECT.is(getRequest().getMethod());
                     if (!persistent)
                         getResponse().getHttpFields().add(HttpHeader.CONNECTION, HttpHeaderValue.CLOSE);
                     break;
                 }
                 default:
                 {
                     throw new IllegalStateException();
                 }
             }
 
             if (!persistent)
                 _generator.setPersistent(false);
 
             return super.headerComplete();
         }
 
         @Override
         protected void handleException(Throwable x)
         {
             _generator.setPersistent(false);
             super.handleException(x);
         }
 
         @Override
         public void failed()
         {
             getEndPoint().shutdownOutput();
         }
     }
 
     private class CommitCallback extends IteratingCallback
     {
         final ByteBuffer _content;
         final boolean _lastContent;
         final ResponseInfo _info;
         ByteBuffer _header;
 
         CommitCallback(ResponseInfo info, ByteBuffer content, boolean last, Callback callback)
         {
             super(callback);
             _info=info;
             _content=content;
             _lastContent=last;
         }
 
         @Override
         public boolean process() throws Exception
         {
             ByteBuffer chunk = _chunk;
             while (true)
             {
                 HttpGenerator.Result result = _generator.generateResponse(_info, _header, chunk, _content, _lastContent);
                 if (LOG.isDebugEnabled())
                     LOG.debug("{} generate: {} ({},{},{})@{}",
                         this,
                         result,
                         BufferUtil.toSummaryString(_header),
                         BufferUtil.toSummaryString(_content),
                         _lastContent,
                         _generator.getState());
 
                 switch (result)
                 {
                     case NEED_HEADER:
                     {
                         if (_lastContent && _content!=null && BufferUtil.space(_content)>_config.getResponseHeaderSize() && _content.hasArray() )
                         {
                             // use spare space in content buffer for header buffer
                             int p=_content.position();
                             int l=_content.limit();
                             _content.position(l);
                             _content.limit(l+_config.getResponseHeaderSize());
                             _header=_content.slice();
                             _header.limit(0);
                             _content.position(p);
                             _content.limit(l);
                         }
                         else
                             _header = _bufferPool.acquire(_config.getResponseHeaderSize(), HEADER_BUFFER_DIRECT);
                         continue;
                     }
                     case NEED_CHUNK:
                     {
                         chunk = _chunk = _bufferPool.acquire(HttpGenerator.CHUNK_SIZE, CHUNK_BUFFER_DIRECT);
                         continue;
                     }
                     case FLUSH:
                     {
                         // Don't write the chunk or the content if this is a HEAD response
                         if (_channel.getRequest().isHead())
                         {
                             BufferUtil.clear(chunk);
                             BufferUtil.clear(_content);
                         }
 
                         // If we have a header
                         if (BufferUtil.hasContent(_header))
                         {
                             if (BufferUtil.hasContent(_content))
                             {
                                 if (BufferUtil.hasContent(chunk))
                                     getEndPoint().write(this, _header, chunk, _content);
                                 else
                                     getEndPoint().write(this, _header, _content);
                             }
                             else
                                 getEndPoint().write(this, _header);
                         }
                         else if (BufferUtil.hasContent(chunk))
                         {
                             if (BufferUtil.hasContent(_content))
                                 getEndPoint().write(this, chunk, _content);
                             else
                                 getEndPoint().write(this, chunk);
                         }
                         else if (BufferUtil.hasContent(_content))
                         {
                             getEndPoint().write(this, _content);
                         }
                         else
                             continue;
                         return false;
                     }
                     case SHUTDOWN_OUT:
                     {
                         getEndPoint().shutdownOutput();
                         continue;
                     }
                     case DONE:
                     {
                         if (_header!=null)
                         {
                             // don't release header in spare content buffer
                             if (!_lastContent || _content==null || !_content.hasArray() || !_header.hasArray() ||  _content.array()!=_header.array())
                                 _bufferPool.release(_header);
                         }
                         return true;
                     }
                     case CONTINUE:
                     {
                         break;
                     }
                     default:
                     {
                         throw new IllegalStateException("generateResponse="+result);
                     }
                 }
             }
         }
     }
 
     private class ContentCallback extends IteratingCallback
     {
         final ByteBuffer _content;
         final boolean _lastContent;
 
         ContentCallback(ByteBuffer content, boolean last, Callback callback)
         {
             super(callback);
             _content=content;
             _lastContent=last;
         }
 
         @Override
         public boolean process() throws Exception
         {
             ByteBuffer chunk = _chunk;
             while (true)
             {
                 HttpGenerator.Result result = _generator.generateResponse(null, null, chunk, _content, _lastContent);
                 if (LOG.isDebugEnabled())
                     LOG.debug("{} generate: {} ({},{})@{}",
                         this,
                         result,
                         BufferUtil.toSummaryString(_content),
                         _lastContent,
                         _generator.getState());
 
                 switch (result)
                 {
                     case NEED_HEADER:
                         throw new IllegalStateException();
                     case NEED_CHUNK:
                     {
                         chunk = _chunk = _bufferPool.acquire(HttpGenerator.CHUNK_SIZE, CHUNK_BUFFER_DIRECT);
                         continue;
                     }
                     case FLUSH:
                     {
                         // Don't write the chunk or the content if this is a HEAD response
                         if (_channel.getRequest().isHead())
                         {
                             BufferUtil.clear(chunk);
                             BufferUtil.clear(_content);
                             continue;
                         }
                         else if (BufferUtil.hasContent(chunk))
                         {
                             if (BufferUtil.hasContent(_content))
                                 getEndPoint().write(this, chunk, _content);
                             else
                                 getEndPoint().write(this, chunk);
                         }
                         else if (BufferUtil.hasContent(_content))
                         {
                             getEndPoint().write(this, _content);
                         }
                         else
                             continue;
                         return false;
                     }
                     case SHUTDOWN_OUT:
                     {
                         getEndPoint().shutdownOutput();
                         continue;
                     }
                     case DONE:
                     {
                         return true;
                     }
                     case CONTINUE:
                     {
                         break;
                     }
                     default:
                     {
                         throw new IllegalStateException("generateResponse="+result);
                     }
                 }
             }
         }
     }
 }