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   /*
    * Copyright 2020 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:
    *
    *   https://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.haproxy;
  
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelOutboundHandlerAdapter;
  import io.netty.channel.ChannelPromise;
  import io.netty.handler.codec.haproxy.HAProxyMessage;
  import io.netty.handler.codec.haproxy.HAProxyMessageEncoder;
  
  public class HAProxyHandler extends ChannelOutboundHandlerAdapter {
  
      @Override
      public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
          ctx.pipeline().addBefore(ctx.name(), null, HAProxyMessageEncoder.INSTANCE);
          super.handlerAdded(ctx);
      }
  
      @Override
      public void write(final ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
          ChannelFuture future = ctx.write(msg, promise);
          if (msg instanceof HAProxyMessage) {
              future.addListener(new ChannelFutureListener() {
                  @Override
                  public void operationComplete(ChannelFuture future) throws Exception {
                      if (future.isSuccess()) {
                          ctx.pipeline().remove(HAProxyMessageEncoder.INSTANCE);
                          ctx.pipeline().remove(HAProxyHandler.this);
                      } else {
                          ctx.close();
                      }
                  }
              });
          }
      }
  }