/*
    * 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 SocksAuthRequest}.
   * Before returning SocksRequest decoder removes itself from pipeline.
   */
  public class SocksAuthRequestDecoder extends ReplayingDecoder<SocksAuthRequestDecoder.State> {
      private static final String name = "SOCKS_AUTH_REQUEST_DECODER";
  
      public static String getName() {
          return name;
      }
  
      private SocksMessage.SubnegotiationVersion version;
      private int fieldLength;
      private String username;
      private String password;
      private SocksRequest msg = SocksCommonUtils.UNKNOWN_SOCKS_REQUEST;
  
      public SocksAuthRequestDecoder() {
          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.SubnegotiationVersion.fromByte(buffer.readByte());
                  if (version != SocksMessage.SubnegotiationVersion.AUTH_PASSWORD) {
                      break;
                  }
                  checkpoint(State.READ_USERNAME);
              }
              case READ_USERNAME: {
                  fieldLength = buffer.readByte();
                  username = buffer.readBytes(fieldLength).toString(CharsetUtil.US_ASCII);
                  checkpoint(State.READ_PASSWORD);
              }
              case READ_PASSWORD: {
                  fieldLength = buffer.readByte();
                  password = buffer.readBytes(fieldLength).toString(CharsetUtil.US_ASCII);
                  msg = new SocksAuthRequest(username, password);
              }
          }
          ctx.getPipeline().remove(this);
          return msg;
      }
  
      enum State {
          CHECK_PROTOCOL_VERSION,
          READ_USERNAME,
          READ_PASSWORD
      }
  }