//
   //  ========================================================================
   //  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.websocket.common.extensions.compress;
  
  
  import java.nio.ByteBuffer;
  
  import org.eclipse.jetty.websocket.api.WriteCallback;
  import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;
  import org.eclipse.jetty.websocket.api.extensions.Frame;
  import org.eclipse.jetty.websocket.common.WebSocketFrame;
  import org.eclipse.jetty.websocket.common.extensions.AbstractExtension;
  
  /**
   * Implementation of the <a href="https://tools.ietf.org/id/draft-tyoshino-hybi-websocket-perframe-deflate-05.txt">x-webkit-deflate-frame</a> extension seen out
   * in the wild.
   */
  public class FrameCompressionExtension extends AbstractExtension
  {
      private CompressionMethod method = new DeflateCompressionMethod();
  
      @Override
      public synchronized void incomingFrame(Frame frame)
      {
          if (frame.getType().isControl() || !frame.isRsv1())
          {
              // Cannot modify incoming control frames or ones with RSV1 set.
              nextIncomingFrame(frame);
              return;
          }
  
          ByteBuffer data = frame.getPayload();
          method.decompress().input(data);
          while (!method.decompress().isDone())
          {
              ByteBuffer uncompressed = method.decompress().process();
              WebSocketFrame out = new WebSocketFrame(frame).setPayload(uncompressed);
              if (!method.decompress().isDone())
              {
                  out.setFin(false);
              }
              out.setRsv1(false); // Unset RSV1 on decompressed frame
              nextIncomingFrame(out);
          }
  
          // reset on every frame.
          // method.decompress().end();
      }
  
      /**
       * Indicates use of RSV1 flag for indicating deflation is in use.
       * <p>
       * Also known as the "COMP" framing header bit
       */
      @Override
      public boolean isRsv1User()
      {
          return true;
      }
  
      /**
       * Indicate that this extensions is now responsible for TEXT Data Frame compliance to the WebSocket spec.
       */
      @Override
      public boolean isTextDataDecoder()
      {
          return true;
      }
  
      @Override
      public synchronized void outgoingFrame(Frame frame, WriteCallback callback)
      {
          if (frame.getType().isControl())
          {
              // skip, cannot compress control frames.
              nextOutgoingFrame(frame,callback);
              return;
          }
  
          ByteBuffer data = frame.getPayload();
  
          // deflate data
          method.compress().input(data);
         while (!method.compress().isDone())
         {
             ByteBuffer buf = method.compress().process();
             WebSocketFrame out = new WebSocketFrame(frame).setPayload(buf);
             out.setRsv1(true);
             if (!method.compress().isDone())
             {
                 out.setFin(false);
                 nextOutgoingFrame(frame,null); // no callback for start/end frames
             }
             else
             {
                 nextOutgoingFrame(out,callback); // pass thru callback
             }
         }
 
         // reset on every frame.
         method.compress().end();
     }
 
     @Override
     public void setConfig(ExtensionConfig config)
     {
         super.setConfig(config);
     }
 
     @Override
     public String toString()
     {
         return this.getClass().getSimpleName() + "[]";
     }
 }