/*
    * Copyright 2013 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.http.websocketx;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelPipeline;
  import io.netty.handler.codec.MessageAggregator;
  import io.netty.handler.codec.TooLongFrameException;
  
  import static io.netty.util.internal.StringUtil.className;
  
  /**
   * Handler that aggregate fragmented WebSocketFrame's.
   *
   * Be aware if PING/PONG/CLOSE frames are send in the middle of a fragmented {@link WebSocketFrame} they will
   * just get forwarded to the next handler in the pipeline.
   */
  public class WebSocketFrameAggregator
          extends MessageAggregator<WebSocketFrame, WebSocketFrame, ContinuationWebSocketFrame, WebSocketFrame> {
  
      /**
       * Creates a new instance
       *
       * @param maxContentLength If the size of the aggregated frame exceeds this value,
       *                         a {@link TooLongFrameException} is thrown.
       */
      public WebSocketFrameAggregator(int maxContentLength) {
          super(maxContentLength, WebSocketFrame.class);
      }
  
      @Override
      protected boolean isStartMessage(WebSocketFrame msg) throws Exception {
          return msg instanceof TextWebSocketFrame || msg instanceof BinaryWebSocketFrame;
      }
  
      @Override
      protected boolean isContentMessage(WebSocketFrame msg) throws Exception {
          return msg instanceof ContinuationWebSocketFrame;
      }
  
      @Override
      protected boolean isLastContentMessage(ContinuationWebSocketFrame msg) throws Exception {
          return isContentMessage(msg) && msg.isFinalFragment();
      }
  
      @Override
      protected boolean isAggregated(WebSocketFrame msg) throws Exception {
          if (msg.isFinalFragment()) {
              return !isContentMessage(msg);
          }
  
          return !isStartMessage(msg) && !isContentMessage(msg);
      }
  
      @Override
      protected boolean isContentLengthInvalid(WebSocketFrame start, int maxContentLength) {
          return false;
      }
  
      @Override
      protected Object newContinueResponse(WebSocketFrame start, int maxContentLength, ChannelPipeline pipeline) {
          return null;
      }
  
      @Override
      protected boolean closeAfterContinueResponse(Object msg) throws Exception {
          throw new UnsupportedOperationException();
      }
  
      @Override
      protected boolean ignoreContentAfterContinueResponse(Object msg) throws Exception {
          throw new UnsupportedOperationException();
      }
  
      @Override
      protected WebSocketFrame beginAggregation(WebSocketFrame start, ByteBuf content) throws Exception {
          if (start instanceof TextWebSocketFrame) {
              return new TextWebSocketFrame(true, start.rsv(), content);
          }
  
          if (start instanceof BinaryWebSocketFrame) {
              return new BinaryWebSocketFrame(true, start.rsv(), content);
          }
  
          // Should not reach here.
          throw new Error("Unexpected websocket frame type: " + className(start));
     }
 }