//
   //  ========================================================================
   //  Copyright (c) 1995-2012 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.websocket.common.extensions.fragment;
  
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.concurrent.Future;
  
  import javax.net.websocket.SendResult;
  
  import org.eclipse.jetty.websocket.api.WebSocketException;
  import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;
  import org.eclipse.jetty.websocket.api.extensions.Frame;
  import org.eclipse.jetty.websocket.common.OpCode;
  import org.eclipse.jetty.websocket.common.WebSocketFrame;
  import org.eclipse.jetty.websocket.common.extensions.AbstractExtension;
  
  /**
   * Fragment Extension
   */
  public class FragmentExtension extends AbstractExtension
  {
      private int maxLength = -1;
  
      @Override
      public void incomingError(WebSocketException e)
      {
          // Pass thru
          nextIncomingError(e);
      }
  
      @Override
      public void incomingFrame(Frame frame)
      {
          // Pass thru
          nextIncomingFrame(frame);
      }
  
      @Override
      public Future<SendResult> outgoingFrame(Frame frame) throws IOException
      {
          if (frame.getType().isControl())
          {
              // Cannot fragment Control Frames
              return nextOutgoingFrame(frame);
          }
  
          int length = frame.getPayloadLength();
  
          byte opcode = frame.getType().getOpCode(); // original opcode
          ByteBuffer payload = frame.getPayload().slice();
          int originalLimit = payload.limit();
          int currentPosition = payload.position();
  
          if (maxLength <= 0)
          {
              // output original frame
              return nextOutgoingFrame(frame);
          }
  
          boolean continuation = false;
  
          // break apart payload based on maxLength rules
          while (length > maxLength)
          {
              WebSocketFrame frag = new WebSocketFrame(frame);
              frag.setOpCode(opcode);
              frag.setFin(false); // always false here
              frag.setContinuation(continuation);
              payload.position(currentPosition);
              payload.limit(Math.min(payload.position() + maxLength,originalLimit));
              frag.setPayload(payload);
  
              nextOutgoingFrame(frag);
  
              length -= maxLength;
              opcode = OpCode.CONTINUATION;
              continuation = true;
              currentPosition = payload.limit();
          }
  
          // write remaining
         WebSocketFrame frag = new WebSocketFrame(frame);
         frag.setOpCode(opcode);
         frag.setFin(frame.isFin()); // use original fin
         frag.setContinuation(continuation);
         payload.position(currentPosition);
         payload.limit(originalLimit);
         frag.setPayload(payload);
 
         return nextOutgoingFrame(frag);
     }
 
     @Override
     public void setConfig(ExtensionConfig config)
     {
         super.setConfig(config);
 
         maxLength = config.getParameter("maxLength",maxLength);
     }
 }