/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project licenses this file to you 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.jboss.netty.handler.codec.http.websocketx;
  
  import org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelHandler.Sharable;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
  
  /**
   * Encodes a {@link WebSocketFrame} into a {@link ChannelBuffer}.
   * <p>
   * For the detailed instruction on adding add Web Socket support to your HTTP server, take a look into the
   * <tt>WebSocketServer</tt> example located in the {@code org.jboss.netty.example.http.websocket} package.
   *
   * @apiviz.landmark
   * @apiviz.uses org.jboss.netty.handler.codec.http.websocket.WebSocketFrame
   */
  @Sharable
  public class WebSocket00FrameEncoder extends OneToOneEncoder {
  
      @Override
      protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
          if (msg instanceof WebSocketFrame) {
              WebSocketFrame frame = (WebSocketFrame) msg;
              if (frame instanceof TextWebSocketFrame) {
                  // Text frame
                  ChannelBuffer data = frame.getBinaryData();
                  ChannelBuffer encoded = channel.getConfig().getBufferFactory()
                          .getBuffer(data.order(), data.readableBytes() + 2);
                  encoded.writeByte((byte) 0x00);
                  encoded.writeBytes(data, data.readerIndex(), data.readableBytes());
                  encoded.writeByte((byte) 0xFF);
                  return encoded;
              } else if (frame instanceof CloseWebSocketFrame) {
                  // Close frame
                  ChannelBuffer data = frame.getBinaryData();
                  ChannelBuffer encoded = channel.getConfig().getBufferFactory().getBuffer(data.order(), 2);
                  encoded.writeByte((byte) 0xFF);
                  encoded.writeByte((byte) 0x00);
                  return encoded;
              } else {
                  // Binary frame
                  ChannelBuffer data = frame.getBinaryData();
                  int dataLen = data.readableBytes();
                  ChannelBuffer encoded = channel.getConfig().getBufferFactory().getBuffer(data.order(), dataLen + 5);
  
                  // Encode type.
                  encoded.writeByte((byte) 0x80);
  
                  // Encode length.
                  int b1 = dataLen >>> 28 & 0x7F;
                  int b2 = dataLen >>> 14 & 0x7F;
                  int b3 = dataLen >>> 7 & 0x7F;
                  int b4 = dataLen & 0x7F;
                  if (b1 == 0) {
                      if (b2 == 0) {
                          if (b3 == 0) {
                              encoded.writeByte(b4);
                          } else {
                              encoded.writeByte(b3 | 0x80);
                              encoded.writeByte(b4);
                          }
                      } else {
                          encoded.writeByte(b2 | 0x80);
                          encoded.writeByte(b3 | 0x80);
                          encoded.writeByte(b4);
                      }
                  } else {
                      encoded.writeByte(b1 | 0x80);
                      encoded.writeByte(b2 | 0x80);
                      encoded.writeByte(b3 | 0x80);
                      encoded.writeByte(b4);
                  }
  
                  // Encode binary data.
                  encoded.writeBytes(data, data.readerIndex(), dataLen);
                  return encoded;
              }
          }
          return msg;
      }
  }