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   /*
    * Copyright 2016 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.handler.codec.http2;
  
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInboundHandlerAdapter;
  import io.netty.handler.codec.http.FullHttpMessage;
  import io.netty.handler.codec.http.HttpHeaders;
  import io.netty.handler.codec.http.HttpScheme;
  import io.netty.util.internal.UnstableApi;
  
  /**
   * Translates HTTP/1.x object reads into HTTP/2 frames.
   */
  @UnstableApi
  public class InboundHttpToHttp2Adapter extends ChannelInboundHandlerAdapter {
      private final Http2Connection connection;
      private final Http2FrameListener listener;
  
      public InboundHttpToHttp2Adapter(Http2Connection connection, Http2FrameListener listener) {
          this.connection = connection;
          this.listener = listener;
      }
  
      private static int getStreamId(Http2Connection connection, HttpHeaders httpHeaders) {
          return httpHeaders.getInt(HttpConversionUtil.ExtensionHeaderNames.STREAM_ID.text(),
                                    connection.remote().incrementAndGetNextStreamId());
      }
  
      @Override
      public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
          if (msg instanceof FullHttpMessage) {
              handle(ctx, connection, listener, (FullHttpMessage) msg);
          } else {
              super.channelRead(ctx, msg);
          }
      }
  
      // note that this may behave strangely when used for the initial upgrade
      // message when using h2c, since that message is ineligible for flow
      // control, but there is not yet an API for signaling that.
      static void handle(ChannelHandlerContext ctx, Http2Connection connection,
                                Http2FrameListener listener, FullHttpMessage message) throws Http2Exception {
          try {
              int streamId = getStreamId(connection, message.headers());
              Http2Stream stream = connection.stream(streamId);
              if (stream == null) {
                  stream = connection.remote().createStream(streamId, false);
              }
              message.headers().set(HttpConversionUtil.ExtensionHeaderNames.SCHEME.text(), HttpScheme.HTTP.name());
              Http2Headers messageHeaders = HttpConversionUtil.toHttp2Headers(message, true);
              boolean hasContent = message.content().isReadable();
              boolean hasTrailers = !message.trailingHeaders().isEmpty();
              listener.onHeadersRead(
                      ctx, streamId, messageHeaders, 0, !(hasContent || hasTrailers));
              if (hasContent) {
                  listener.onDataRead(ctx, streamId, message.content(), 0, !hasTrailers);
              }
              if (hasTrailers) {
                  Http2Headers headers = HttpConversionUtil.toHttp2Headers(message.trailingHeaders(), true);
                  listener.onHeadersRead(ctx, streamId, headers, 0, true);
              }
              stream.closeRemoteSide();
          } finally {
              message.release();
          }
      }
  }