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   /*
    * 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:
    *
    * 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.http2.helloworld.client;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelPromise;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.codec.http.FullHttpResponse;
  import io.netty.handler.codec.http2.HttpConversionUtil;
  import io.netty.util.CharsetUtil;
  import io.netty.util.internal.PlatformDependent;
  
  import java.util.AbstractMap.SimpleEntry;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Process {@link io.netty.handler.codec.http.FullHttpResponse} translated from HTTP/2 frames
   */
  public class HttpResponseHandler extends SimpleChannelInboundHandler<FullHttpResponse> {
  
      private final Map<Integer, Entry<ChannelFuture, ChannelPromise>> streamidPromiseMap;
  
      public HttpResponseHandler() {
          // Use a concurrent map because we add and iterate from the main thread (just for the purposes of the example),
          // but Netty also does a get on the map when messages are received in a EventLoop thread.
          streamidPromiseMap = PlatformDependent.newConcurrentHashMap();
      }
  
      /**
       * Create an association between an anticipated response stream id and a {@link io.netty.channel.ChannelPromise}
       *
       * @param streamId The stream for which a response is expected
       * @param writeFuture A future that represent the request write operation
       * @param promise The promise object that will be used to wait/notify events
       * @return The previous object associated with {@code streamId}
       * @see HttpResponseHandler#awaitResponses(long, java.util.concurrent.TimeUnit)
       */
      public Entry<ChannelFuture, ChannelPromise> put(int streamId, ChannelFuture writeFuture, ChannelPromise promise) {
          return streamidPromiseMap.put(streamId, new SimpleEntry<ChannelFuture, ChannelPromise>(writeFuture, promise));
      }
  
      /**
       * Wait (sequentially) for a time duration for each anticipated response
       *
       * @param timeout Value of time to wait for each response
       * @param unit Units associated with {@code timeout}
       * @see HttpResponseHandler#put(int, io.netty.channel.ChannelFuture, io.netty.channel.ChannelPromise)
       */
      public void awaitResponses(long timeout, TimeUnit unit) {
          Iterator<Entry<Integer, Entry<ChannelFuture, ChannelPromise>>> itr = streamidPromiseMap.entrySet().iterator();
          while (itr.hasNext()) {
              Entry<Integer, Entry<ChannelFuture, ChannelPromise>> entry = itr.next();
              ChannelFuture writeFuture = entry.getValue().getKey();
              if (!writeFuture.awaitUninterruptibly(timeout, unit)) {
                  throw new IllegalStateException("Timed out waiting to write for stream id " + entry.getKey());
              }
              if (!writeFuture.isSuccess()) {
                  throw new RuntimeException(writeFuture.cause());
              }
              ChannelPromise promise = entry.getValue().getValue();
              if (!promise.awaitUninterruptibly(timeout, unit)) {
                  throw new IllegalStateException("Timed out waiting for response on stream id " + entry.getKey());
              }
              if (!promise.isSuccess()) {
                  throw new RuntimeException(promise.cause());
              }
              System.out.println("---Stream id: " + entry.getKey() + " received---");
              itr.remove();
          }
      }
  
      @Override
      protected void channelRead0(ChannelHandlerContext ctx, FullHttpResponse msg) throws Exception {
          Integer streamId = msg.headers().getInt(HttpConversionUtil.ExtensionHeaderNames.STREAM_ID.text());
          if (streamId == null) {
              System.err.println("HttpResponseHandler unexpected message received: " + msg);
              return;
          }
  
          Entry<ChannelFuture, ChannelPromise> entry = streamidPromiseMap.get(streamId);
          if (entry == null) {
              System.err.println("Message received for unknown stream id " + streamId);
         } else {
             // Do stuff with the message (for now just print it)
             ByteBuf content = msg.content();
             if (content.isReadable()) {
                 int contentLength = content.readableBytes();
                 byte[] arr = new byte[contentLength];
                 content.readBytes(arr);
                 System.out.println(new String(arr, 0, contentLength, CharsetUtil.UTF_8));
             }
 
             entry.getValue().setSuccess();
         }
     }
 }