/*
    * 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;
  import org.jboss.netty.util.CharsetUtil;
  
  /**
   * Decodes {@link ChannelBuffer}s into {@link SocksCmdResponse}.
   * Before returning SocksResponse decoder removes itself from pipeline.
   */
  public class SocksCmdResponseDecoder extends ReplayingDecoder<SocksCmdResponseDecoder.State> {
  
      private SocksMessage.ProtocolVersion version;
      private int fieldLength;
      private SocksMessage.CmdStatus cmdStatus;
      private SocksMessage.AddressType addressType;
      private byte reserved;
      private String host;
      private int port;
      private SocksResponse msg = SocksCommonUtils.UNKNOWN_SOCKS_RESPONSE;
  
      public SocksCmdResponseDecoder() {
          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_CMD_HEADER);
              }
              case READ_CMD_HEADER: {
                  cmdStatus = SocksMessage.CmdStatus.fromByte(buffer.readByte());
                  reserved = buffer.readByte();
                  addressType = SocksMessage.AddressType.fromByte(buffer.readByte());
                  checkpoint(State.READ_CMD_ADDRESS);
              }
              case READ_CMD_ADDRESS: {
                  switch (addressType) {
                      case IPv4: {
                          host = SocksCommonUtils.intToIp(buffer.readInt());
                          port = buffer.readUnsignedShort();
                          msg = new SocksCmdResponse(cmdStatus, addressType);
                          break;
                      }
                      case DOMAIN: {
                          fieldLength = buffer.readByte();
                          host = buffer.readBytes(fieldLength).toString(CharsetUtil.US_ASCII);
                          port = buffer.readUnsignedShort();
                          msg = new SocksCmdResponse(cmdStatus, addressType);
                          break;
                      }
                      case IPv6: {
                          host = SocksCommonUtils.ipv6toStr(buffer.readBytes(16).array());
                          port = buffer.readUnsignedShort();
                          msg = new SocksCmdResponse(cmdStatus, addressType);
                          break;
                      }
                      case UNKNOWN:
                          break;
                  }
              }
          }
          ctx.getPipeline().remove(this);
          return msg;
      }
  
      public enum State {
          CHECK_PROTOCOL_VERSION,
          READ_CMD_HEADER,
          READ_CMD_ADDRESS
      }
  }