/*
    * 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.socks;
  
  import org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.handler.codec.replay.ReplayingDecoder;
  
  /**
   * Decodes {@link ChannelBuffer}s into {@link SocksInitResponse}.
   * Before returning SocksResponse decoder removes itself from pipeline.
   */
  public class SocksInitResponseDecoder extends ReplayingDecoder<SocksInitResponseDecoder.State> {
      private static final String name = "SOCKS_INIT_RESPONSE_DECODER";
  
      public static String getName() {
          return name;
      }
  
      private SocksMessage.ProtocolVersion version;
      private SocksMessage.AuthScheme authScheme;
  
      private SocksResponse msg = SocksCommonUtils.UNKNOWN_SOCKS_RESPONSE;
  
      public SocksInitResponseDecoder() {
          super(State.CHECK_PROTOCOL_VERSION);
      }
  
      @Override
      protected Object decode(ChannelHandlerContext ctx, Channel channel,
                              ChannelBuffer buffer, State state) throws Exception {
          switch (state) {
              case CHECK_PROTOCOL_VERSION: {
                  version = SocksMessage.ProtocolVersion.fromByte(buffer.readByte());
                  if (version != SocksMessage.ProtocolVersion.SOCKS5) {
                      break;
                  }
                  checkpoint(State.READ_PREFFERED_AUTH_TYPE);
              }
              case READ_PREFFERED_AUTH_TYPE: {
                  authScheme = SocksMessage.AuthScheme.fromByte(buffer.readByte());
                  msg = new SocksInitResponse(authScheme);
                  break;
              }
          }
          ctx.getPipeline().remove(this);
          return msg;
      }
  
      public enum State {
          CHECK_PROTOCOL_VERSION,
          READ_PREFFERED_AUTH_TYPE
      }
  }