/*
    * 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 io.netty.example.socksproxy;
  
  import io.netty.bootstrap.Bootstrap;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.channel.socket.nio.NioSocketChannel;
  import io.netty.handler.codec.socks.SocksCmdRequest;
  import io.netty.handler.codec.socks.SocksCmdResponse;
  import io.netty.handler.codec.socks.SocksCmdStatus;
  import io.netty.util.concurrent.Future;
  import io.netty.util.concurrent.GenericFutureListener;
  import io.netty.util.concurrent.Promise;
  
  @ChannelHandler.Sharable
  public final class SocksServerConnectHandler extends SimpleChannelInboundHandler<SocksCmdRequest> {
  
      private final Bootstrap b = new Bootstrap();
  
      @Override
      public void channelRead0(final ChannelHandlerContext ctx, final SocksCmdRequest request) throws Exception {
          Promise<Channel> promise = ctx.executor().newPromise();
          promise.addListener(
              new GenericFutureListener<Future<Channel>>() {
              @Override
              public void operationComplete(final Future<Channel> future) throws Exception {
                  final Channel outboundChannel = future.getNow();
                  if (future.isSuccess()) {
                      ctx.channel().writeAndFlush(new SocksCmdResponse(SocksCmdStatus.SUCCESS, request.addressType()))
                              .addListener(new ChannelFutureListener() {
                                  @Override
                                  public void operationComplete(ChannelFuture channelFuture) {
                                      ctx.pipeline().remove(SocksServerConnectHandler.this);
                                      outboundChannel.pipeline().addLast(new RelayHandler(ctx.channel()));
                                      ctx.pipeline().addLast(new RelayHandler(outboundChannel));
                                  }
                              });
                  } else {
                      ctx.channel().writeAndFlush(new SocksCmdResponse(SocksCmdStatus.FAILURE, request.addressType()));
                      SocksServerUtils.closeOnFlush(ctx.channel());
                  }
              }
          });
  
          final Channel inboundChannel = ctx.channel();
          b.group(inboundChannel.eventLoop())
                  .channel(NioSocketChannel.class)
                  .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 10000)
                  .option(ChannelOption.SO_KEEPALIVE, true)
                  .handler(new DirectClientHandler(promise));
  
          b.connect(request.host(), request.port()).addListener(new ChannelFutureListener() {
              @Override
              public void operationComplete(ChannelFuture future) throws Exception {
                  if (future.isSuccess()) {
                      // Connection established use handler provided results
                  } else {
                      // Close the connection if the connection attempt has failed.
                      ctx.channel().writeAndFlush(
                              new SocksCmdResponse(SocksCmdStatus.FAILURE, request.addressType()));
                      SocksServerUtils.closeOnFlush(ctx.channel());
                  }
              }
          });
      }
  
      @Override
      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
          SocksServerUtils.closeOnFlush(ctx.channel());
      }
  }