//
   //  ========================================================================
   //  Copyright (c) 1995-2015 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.WritePendingException;
  import java.util.concurrent.RejectedExecutionException;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.eclipse.jetty.http.HttpField;
  import org.eclipse.jetty.http.HttpGenerator;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpHeaderValue;
  import org.eclipse.jetty.http.HttpParser;
  import org.eclipse.jetty.http.HttpParser.RequestHandler;
  import org.eclipse.jetty.http.HttpStatus;
  import org.eclipse.jetty.http.MetaData;
  import org.eclipse.jetty.http.PreEncodedHttpField;
  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.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, Connection.UpgradeFrom
  {
      private static final Logger LOG = Log.getLogger(HttpConnection.class);
      public static final HttpField CONNECTION_CLOSE = new PreEncodedHttpField(HttpHeader.CONNECTION,HttpHeaderValue.CLOSE.asString());
      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 ThreadLocal<HttpConnection> __currentConnection = new ThreadLocal<>();
  
      private final HttpConfiguration _config;
      private final Connector _connector;
      private final ByteBufferPool _bufferPool;
      private final HttpInput _input;
      private final HttpGenerator _generator;
      private final HttpChannelOverHttp _channel;
      private final HttpParser _parser;
      private final AtomicInteger _contentBufferReferences=new AtomicInteger();
      private volatile ByteBuffer _requestBuffer = null;
      private volatile ByteBuffer _chunk = null;
      private final BlockingReadCallback _blockingReadCallback = new BlockingReadCallback();
      private final AsyncReadCallback _asyncReadCallback = new AsyncReadCallback();
      private final SendCallback _sendCallback = new SendCallback();
  
      /**
       * Get the current connection that this thread is dispatched to.
       * Note that a thread may be processing a request asynchronously and
       * thus not be dispatched to the connection.
       * @return the current HttpConnection or null
       * @see Request#getAttribute(String) for a more general way to access the HttpConnection
       */
      public static HttpConnection getCurrentConnection()
      {
          return __currentConnection.get();
      }
  
      protected static HttpConnection setCurrentConnection(HttpConnection connection)
      {
          HttpConnection last=__currentConnection.get();
          __currentConnection.set(connection);
          return last;
      }
  
      public HttpConnection(HttpConfiguration config, Connector connector, EndPoint endPoint)
      {
          super(endPoint, connector.getExecutor());
          _config = config;
          _connector = connector;
          _bufferPool = _connector.getByteBufferPool();
          _generator = newHttpGenerator();
         _channel = newHttpChannel();
         _input = _channel.getRequest().getHttpInput();
         _parser = newHttpParser();
         if (LOG.isDebugEnabled())
             LOG.debug("New HTTP Connection {}", this);
     }
 
     public HttpConfiguration getHttpConfiguration()
     {
         return _config;
     }
 
     protected HttpGenerator newHttpGenerator()
     {
         return new HttpGenerator(_config.getSendServerVersion(),_config.getSendXPoweredBy());
     }
 
     protected HttpChannelOverHttp newHttpChannel()
     {
         return new HttpChannelOverHttp(this, _connector, _config, getEndPoint(), this);
     }
 
     protected HttpParser newHttpParser()
     {
         return new HttpParser(newRequestHandler(), getHttpConfiguration().getRequestHeaderSize());
     }
 
     protected HttpParser.RequestHandler newRequestHandler()
     {
         return _channel;
     }
 
     public Server getServer()
     {
         return _connector.getServer();
     }
 
     public Connector getConnector()
     {
         return _connector;
     }
 
     public HttpChannel getHttpChannel()
     {
         return _channel;
     }
 
     public HttpParser getParser()
     {
         return _parser;
     }
 
     public HttpGenerator getGenerator()
     {
         return _generator;
     }
 
     @Override
     public boolean isOptimizedForDirectBuffers()
     {
         return getEndPoint().isOptimizedForDirectBuffers();
     }
 
     @Override
     public int getMessagesIn()
     {
         return getHttpChannel().getRequests();
     }
 
     @Override
     public int getMessagesOut()
     {
         return getHttpChannel().getRequests();
     }
 
     @Override
     public ByteBuffer onUpgradeFrom()
     {
         if (BufferUtil.hasContent(_requestBuffer))
         {
             ByteBuffer buffer = _requestBuffer;
             _requestBuffer=null;
             return buffer;
         }
         return null;
     }
 
     void releaseRequestBuffer()
     {
         if (_requestBuffer != null && !_requestBuffer.hasRemaining())
         {
             if (LOG.isDebugEnabled())
                 LOG.debug("releaseRequestBuffer {}",this);
             ByteBuffer buffer=_requestBuffer;
             _requestBuffer=null;
             _bufferPool.release(buffer);
         }
     }
 
     public ByteBuffer getRequestBuffer()
     {
         if (_requestBuffer == null)
             _requestBuffer = _bufferPool.acquire(getInputBufferSize(), REQUEST_BUFFER_DIRECT);
         return _requestBuffer;
     }
 
     public boolean isRequestBufferEmpty()
     {
         return BufferUtil.isEmpty(_requestBuffer);
     }
 
     @Override
     public void onFillable()
     {
         if (LOG.isDebugEnabled())
             LOG.debug("{} onFillable enter {}", this, _channel.getState());
 
         HttpConnection last=setCurrentConnection(this);
         try
         {
             while (true)
             {
                 // Fill the request buffer (if needed)
                 int filled = fillRequestBuffer();
 
                 // Parse the request buffer
                 boolean handle = parseRequestBuffer();
                 // If there was a connection upgrade, the other
                 // connection took over, nothing more to do here.
                 if (getEndPoint().getConnection()!=this)
                     break;
 
                 // Handle close parser
                 if (_parser.isClose() || _parser.isClosed())
                 {
                     close();
                     break;
                 }
 
                 // Handle channel event
                 if (handle)
                 {
                     boolean suspended = !_channel.handle();
 
                     // We should break iteration if we have suspended or changed connection or this is not the handling thread.
                     if (suspended || getEndPoint().getConnection() != this)
                         break;
                 }
 
                 // Continue or break?
                 else if (filled<=0)
                 {
                     if (filled==0)
                         fillInterested();
                     break;
                 }
             }
         }
         finally
         {
             setCurrentConnection(last);
             if (LOG.isDebugEnabled())
                 LOG.debug("{} onFillable exit {}", this, _channel.getState());
         }
     }
 
     /* ------------------------------------------------------------ */
     /** Fill and parse data looking for content
      * @return true if an {@link RequestHandler} method was called and it returned true;
      */
     protected boolean fillAndParseForContent()
     {
         boolean handled=false;
         while (_parser.inContentState())
         {
             if (LOG.isDebugEnabled())
                 LOG.debug("{} parseContent",this);
             int filled = fillRequestBuffer();
             boolean handle = parseRequestBuffer();
             handled|=handle;
             if (handle || filled<=0 || _channel.getRequest().getHttpInput().hasContent())
                 break;
         }
         return handled;
     }
 
     /* ------------------------------------------------------------ */
     private int fillRequestBuffer()
     {
         if (_contentBufferReferences.get()>0)
         {
             LOG.warn("{} fill with unconsumed content!",this);
             return 0;
         }
 
         if (BufferUtil.isEmpty(_requestBuffer))
         {
             // Can we fill?
             if(getEndPoint().isInputShutdown())
             {
                 // No pretend we read -1
                 _parser.atEOF();
                 if (LOG.isDebugEnabled())
                     LOG.debug("{} filled -1",this);
                 return -1;
             }
 
             // Get a buffer
             // We are not in a race here for the request buffer as we have not yet received a request,
             // so there are not an possible legal threads calling #parseContent or #completed.
             _requestBuffer = getRequestBuffer();
 
             // fill
             try
             {
                 int filled = getEndPoint().fill(_requestBuffer);
                 if (filled==0) // Do a retry on fill 0 (optimization for SSL connections)
                     filled = getEndPoint().fill(_requestBuffer);
 
                 // tell parser
                 if (filled < 0)
                     _parser.atEOF();
 
                 if (LOG.isDebugEnabled())
                     LOG.debug("{} filled {}",this,filled);
 
                 return filled;
             }
             catch (IOException e)
             {
                 LOG.debug(e);
                 return -1;
             }
         }
         return 0;
     }
 
     /* ------------------------------------------------------------ */
     private boolean parseRequestBuffer()
     {
         if (LOG.isDebugEnabled())
             LOG.debug("{} parse {} {}",this,BufferUtil.toDetailString(_requestBuffer));
 
         boolean handle = _parser.parseNext(_requestBuffer==null?BufferUtil.EMPTY_BUFFER:_requestBuffer);
 
         if (LOG.isDebugEnabled())
             LOG.debug("{} parsed {} {}",this,handle,_parser);
 
         // recycle buffer ?
         if (_contentBufferReferences.get()==0)
             releaseRequestBuffer();
 
         return handle;
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public void onCompleted()
     {
         // Handle connection upgrades
         if (_channel.getResponse().getStatus() == HttpStatus.SWITCHING_PROTOCOLS_101)
         {
             Connection connection = (Connection)_channel.getRequest().getAttribute(UPGRADE_CONNECTION_ATTRIBUTE);
             if (connection != null)
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug("Upgrade from {} to {}", this, connection);
                 _channel.getState().upgrade();
                 getEndPoint().upgrade(connection);
                 _channel.recycle();
                 _parser.reset();
                 _generator.reset();
                 if (_contentBufferReferences.get()==0)
                     releaseRequestBuffer();
                 else
                 {
                     LOG.warn("{} lingering content references?!?!",this);
                     _requestBuffer=null; // Not returned to pool!
                     _contentBufferReferences.set(0);
                 }
                 return;
             }
         }
 
         // Finish consuming the request
         // If we are still expecting
         if (_channel.isExpecting100Continue())
         {
             // close to seek EOF
             _parser.close();
         }
         else if (_parser.inContentState() && _generator.isPersistent())
         {
             // If we are async, then we have problems to complete neatly
             if (_channel.getRequest().getHttpInput().isAsync())
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug("unconsumed async input {}", this);
                 _channel.abort(new IOException("unconsumed input"));
             }
             else
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug("unconsumed input {}", this);
                 // Complete reading the request
                 if (!_channel.getRequest().getHttpInput().consumeAll())
                     _channel.abort(new IOException("unconsumed input"));
             }
         }
 
         // Reset the channel, parsers and generator
         _channel.recycle();
         if (_generator.isPersistent() && !_parser.isClosed())
             _parser.reset();
         else
             _parser.close();
 
         // Not in a race here with onFillable, because it has given up control before calling handle.
         // in a slight race with #completed, but not sure what to do with that anyway.
         if (_chunk!=null)
             _bufferPool.release(_chunk);
         _chunk=null;
         _generator.reset();
 
         // if we are not called from the onfillable thread, schedule completion
         if (getCurrentConnection()!=this)
         {
             // If we are looking for the next request
             if (_parser.isStart())
             {
                 // if the buffer is empty
                 if (BufferUtil.isEmpty(_requestBuffer))
                 {
                     // look for more data
                     fillInterested();
                 }
                 // else if we are still running
                 else if (getConnector().isRunning())
                 {
                     // Dispatched to handle a pipelined request
                     try
                     {
                         getExecutor().execute(this);
                     }
                     catch (RejectedExecutionException e)
                     {
                         if (getConnector().isRunning())
                             LOG.warn(e);
                         else
                             LOG.ignore(e);
                         getEndPoint().close();
                     }
                 }
                 else
                 {
                     getEndPoint().close();
                 }
             }
             // else the parser must be closed, so seek the EOF if we are still open
             else if (getEndPoint().isOpen())
                 fillInterested();
         }
     }
 
     @Override
     protected void onFillInterestedFailed(Throwable cause)
     {
         _parser.close();
         super.onFillInterestedFailed(cause);
     }
 
     @Override
     public void onOpen()
     {
         super.onOpen();
         fillInterested();
     }
 
     @Override
     public void onClose()
     {
         _sendCallback.close();
         super.onClose();
     }
 
     @Override
     public void run()
     {
         onFillable();
     }
 
     @Override
     public void send(MetaData.Response info, boolean head, ByteBuffer content, boolean lastContent, Callback callback)
     {
         if (info == null)
         {
             if (!lastContent && BufferUtil.isEmpty(content))
             {
                 callback.succeeded();
                 return;
             }
         }
         else
         {
             // If we are still expecting a 100 continues when we commit
             if (_channel.isExpecting100Continue())
                 // then we can't be persistent
                 _generator.setPersistent(false);
         }
 
         if(_sendCallback.reset(info,head,content,lastContent,callback))
             _sendCallback.iterate();
     }
 
 
     HttpInput.Content newContent(ByteBuffer c)
     {
         return new Content(c);
     }
 
     @Override
     public void abort(Throwable failure)
     {
         // Do a direct close of the output, as this may indicate to a client that the
         // response is bad either with RST or by abnormal completion of chunked response.
         getEndPoint().close();
     }
 
     @Override
     public boolean isPushSupported()
     {
         return false;
     }
 
     @Override
     public void push(org.eclipse.jetty.http.MetaData.Request request)
     {
         LOG.debug("ignore push in {}",this);
     }
 
     public void asyncReadFillInterested()
     {
         getEndPoint().fillInterested(_asyncReadCallback);
     }
 
     public void blockingReadFillInterested()
     {
         getEndPoint().fillInterested(_blockingReadCallback);
     }
 
     public void blockingReadException(Throwable e)
     {
         _blockingReadCallback.failed(e);
     }
 
     @Override
     public String toString()
     {
         return String.format("%s[p=%s,g=%s,c=%s][b=%s]",
                 super.toString(),
                 _parser,
                 _generator,
                 _channel,
                 BufferUtil.toDetailString(_requestBuffer));
     }
 
     private class Content extends HttpInput.Content
     {
         public Content(ByteBuffer content)
         {
             super(content);
             _contentBufferReferences.incrementAndGet();
         }
 
         @Override
         public void succeeded()
         {
             if (_contentBufferReferences.decrementAndGet()==0)
                 releaseRequestBuffer();
         }
 
         @Override
         public void failed(Throwable x)
         {
             succeeded();
         }
     }
 
     private class BlockingReadCallback implements Callback
     {
         @Override
         public void succeeded()
         {
             _input.unblock();
         }
 
         @Override
         public void failed(Throwable x)
         {
             _input.failed(x);
         }
 
         @Override
         public boolean isNonBlocking()
         {
             // This callback does not block, rather it wakes up the
             // thread that is blocked waiting on the read.
             return true;
         }
     }
 
     private class AsyncReadCallback implements Callback
     {
         @Override
         public void succeeded()
         {
             if (fillAndParseForContent())
                 _channel.handle();
             else if (!_input.isFinished())
                 asyncReadFillInterested();
         }
 
         @Override
         public void failed(Throwable x)
         {
             if (_input.failed(x))
                 _channel.handle();
         }
     }
 
     private class SendCallback extends IteratingCallback
     {
         private MetaData.Response _info;
         private boolean _head;
         private ByteBuffer _content;
         private boolean _lastContent;
         private Callback _callback;
         private ByteBuffer _header;
         private boolean _shutdownOut;
 
         private SendCallback()
         {
             super(true);
         }
 
         @Override
         public boolean isNonBlocking()
         {
             return _callback.isNonBlocking();
         }
 
         private boolean reset(MetaData.Response info, boolean head, ByteBuffer content, boolean last, Callback callback)
         {
             if (reset())
             {
                 _info = info;
                 _head = head;
                 _content = content;
                 _lastContent = last;
                 _callback = callback;
                 _header = null;
                 _shutdownOut = false;
                 return true;
             }
 
             if (isClosed())
                 callback.failed(new EofException());
             else
                 callback.failed(new WritePendingException());
             return false;
         }
 
         @Override
         public Action process() throws Exception
         {
             if (_callback==null)
                 throw new IllegalStateException();
 
             ByteBuffer chunk = _chunk;
             while (true)
             {
                 HttpGenerator.Result result = _generator.generateResponse(_info, _head, _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:
                     {
                         // Look for optimisation to avoid allocating a _header buffer
                         /*
                          Cannot use this optimisation unless we work out how not to overwrite data in user passed arrays.
                         if (_lastContent && _content!=null && !_content.isReadOnly() && _content.hasArray() && BufferUtil.space(_content)>_config.getResponseHeaderSize() )
                         {
                             // 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, or any other type of response that should have no content
                         if (_head || _generator.isNoContent())
                         {
                             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
                         {
                             succeeded(); // nothing to write
                         }
                         return Action.SCHEDULED;
                     }
                     case SHUTDOWN_OUT:
                     {
                         _shutdownOut=true;
                         continue;
                     }
                     case DONE:
                     {
                         return Action.SUCCEEDED;
                     }
                     case CONTINUE:
                     {
                         break;
                     }
                     default:
                     {
                         throw new IllegalStateException("generateResponse="+result);
                     }
                 }
             }
         }
 
         private void releaseHeader()
         {
             ByteBuffer h=_header;
             _header=null;
             if (h!=null)
                 _bufferPool.release(h);
         }
 
         @Override
         protected void onCompleteSuccess()
         {
             releaseHeader();
             _callback.succeeded();
             if (_shutdownOut)
                 getEndPoint().shutdownOutput();
         }
 
         @Override
         public void onCompleteFailure(final Throwable x)
         {
             releaseHeader();
             failedCallback(_callback,x);
             if (_shutdownOut)
                 getEndPoint().shutdownOutput();
         }
 
         @Override
         public String toString()
         {
             return String.format("%s[i=%s,cb=%s]",super.toString(),_info,_callback);
         }
     }
 }