/*
    * Copyright 2014 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.handler.ipfilter;
  
  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.util.internal.ConcurrentSet;
  
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.util.Set;
  
  /**
   * This class allows one to ensure that at all times for every IP address there is at most one
   * {@link Channel} connected to the server.
   */
  @ChannelHandler.Sharable
  public class UniqueIpFilter extends AbstractRemoteAddressFilter<InetSocketAddress> {
  
      private final Set<InetAddress> connected = new ConcurrentSet<InetAddress>();
  
      @Override
      protected boolean accept(ChannelHandlerContext ctx, InetSocketAddress remoteAddress) throws Exception {
          final InetAddress remoteIp = remoteAddress.getAddress();
          if (connected.contains(remoteIp)) {
              return false;
          } else {
              connected.add(remoteIp);
              ctx.channel().closeFuture().addListener(new ChannelFutureListener() {
                  @Override
                  public void operationComplete(ChannelFuture future) throws Exception {
                      connected.remove(remoteIp);
                  }
              });
              return true;
          }
      }
  }