/*
    * 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.netty5.handler.codec.http.websocketx;
  
  import io.netty5.buffer.api.BufferAllocator;
  import io.netty5.buffer.api.CompositeBuffer;
  import io.netty5.channel.ChannelPipeline;
  import io.netty5.handler.codec.MessageAggregator;
  import io.netty5.handler.codec.TooLongFrameException;
  
  /**
   * 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);
      }
  
      @Override
      protected WebSocketFrame tryStartMessage(Object msg) {
          return isStartMessage(msg) ? (WebSocketFrame) msg : null;
      }
  
      @Override
      protected ContinuationWebSocketFrame tryContentMessage(Object msg) {
          return isContentMessage(msg) ? (ContinuationWebSocketFrame) msg : null;
      }
  
      @Override
      protected boolean isLastContentMessage(ContinuationWebSocketFrame msg) {
          return isContentMessage(msg) && msg.isFinalFragment();
      }
  
      @Override
      protected boolean isAggregated(Object msg) throws Exception {
          if (!(msg instanceof WebSocketFrame)) {
              return false;
          }
          WebSocketFrame frame = (WebSocketFrame) msg;
          if (frame.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 int lengthForContent(ContinuationWebSocketFrame msg) {
          return msg.binaryData().readableBytes();
      }
  
      @Override
      protected int lengthForAggregation(WebSocketFrame msg) {
          return msg.binaryData().readableBytes();
      }
 
     @Override
     protected WebSocketFrame beginAggregation(BufferAllocator allocator, WebSocketFrame start) {
         if (start instanceof TextWebSocketFrame) {
             final CompositeBuffer content = allocator.compose(start.binaryData().send());
             return new TextWebSocketFrame(true, start.rsv(), content);
         }
 
         if (start instanceof BinaryWebSocketFrame) {
             final CompositeBuffer content = allocator.compose(start.binaryData().send());
             return new BinaryWebSocketFrame(true, start.rsv(), content);
         }
 
         // Should not reach here.
         throw new Error();
     }
 
     @Override
     protected void aggregate(BufferAllocator allocator, WebSocketFrame aggregated, ContinuationWebSocketFrame content)
             throws Exception {
         final CompositeBuffer payload = (CompositeBuffer) aggregated.binaryData();
         payload.extendWith(content.binaryData().send());
     }
 
     private static boolean isStartMessage(Object msg) {
         return msg instanceof TextWebSocketFrame || msg instanceof BinaryWebSocketFrame;
     }
 
     private static boolean isContentMessage(Object msg) {
         return msg instanceof ContinuationWebSocketFrame;
     }
 }