//
   //  ========================================================================
   //  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.spdy.generator;
  
  import java.nio.ByteBuffer;
  
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.spdy.SessionException;
  import org.eclipse.jetty.spdy.api.SPDY;
  import org.eclipse.jetty.spdy.api.SessionStatus;
  import org.eclipse.jetty.spdy.frames.ControlFrame;
  import org.eclipse.jetty.spdy.frames.HeadersFrame;
  import org.eclipse.jetty.util.BufferUtil;
  
  public class HeadersGenerator extends ControlFrameGenerator
  {
      private final HeadersBlockGenerator headersBlockGenerator;
  
      public HeadersGenerator(ByteBufferPool bufferPool, HeadersBlockGenerator headersBlockGenerator)
      {
          super(bufferPool);
          this.headersBlockGenerator = headersBlockGenerator;
      }
  
      @Override
      public ByteBuffer generate(ControlFrame frame)
      {
          HeadersFrame headers = (HeadersFrame)frame;
          short version = headers.getVersion();
  
          ByteBuffer headersBuffer = headersBlockGenerator.generate(version, headers.getHeaders());
  
          int frameBodyLength = 4;
          if (frame.getVersion() == SPDY.V2)
              frameBodyLength += 2;
  
          int frameLength = frameBodyLength + headersBuffer.remaining();
          if (frameLength > 0xFF_FF_FF)
          {
              // Too many headers, but unfortunately we have already modified the compression
              // context, so we have no other choice than tear down the connection.
              throw new SessionException(SessionStatus.PROTOCOL_ERROR, "Too many headers");
          }
  
          int totalLength = ControlFrame.HEADER_LENGTH + frameLength;
  
          ByteBuffer buffer = getByteBufferPool().acquire(totalLength, Generator.useDirectBuffers);
          BufferUtil.clearToFill(buffer);
          generateControlFrameHeader(headers, frameLength, buffer);
  
          buffer.putInt(headers.getStreamId() & 0x7F_FF_FF_FF);
          if (frame.getVersion() == SPDY.V2)
              buffer.putShort((short)0);
  
          buffer.put(headersBuffer);
  
          buffer.flip();
          return buffer;
      }
  }