/*
    * Copyright (c) 2012 the original author or authors.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.eclipse.jetty.spdy.generator;
  
  import java.nio.ByteBuffer;
  
  import org.eclipse.jetty.spdy.ByteBufferPool;
  import org.eclipse.jetty.spdy.SessionException;
  import org.eclipse.jetty.spdy.api.SessionStatus;
  import org.eclipse.jetty.spdy.frames.ControlFrame;
  import org.eclipse.jetty.spdy.frames.HeadersFrame;
  
  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;
  
          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, true);
          generateControlFrameHeader(headers, frameLength, buffer);
  
          buffer.putInt(headers.getStreamId() & 0x7F_FF_FF_FF);
  
          buffer.put(headersBuffer);
  
          buffer.flip();
          return buffer;
      }
  }