/*
    * 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.redis;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelPipeline;
  import io.netty.handler.codec.MessageAggregator;
  import io.netty.util.internal.UnstableApi;
  
  /**
   * A {@link ChannelHandler} that aggregates an {@link BulkStringHeaderRedisMessage}
   * and its following {@link BulkStringRedisContent}s into a single {@link FullBulkStringRedisMessage}
   * with no following {@link BulkStringRedisContent}s.  It is useful when you don't want to take
   * care of {@link RedisMessage}s whose transfer encoding is 'chunked'.  Insert this
   * handler after {@link RedisDecoder} in the {@link ChannelPipeline}:
   * <pre>
   * {@link ChannelPipeline} p = ...;
   * ...
   * p.addLast("encoder", new {@link RedisEncoder}());
   * p.addLast("decoder", new {@link RedisDecoder}());
   * p.addLast("aggregator", <b>new {@link RedisBulkStringAggregator}()</b>);
   * ...
   * p.addLast("handler", new HttpRequestHandler());
   * </pre>
   * Be aware that you need to have the {@link RedisEncoder} before the {@link RedisBulkStringAggregator}
   * in the {@link ChannelPipeline}.
   */
  @UnstableApi
  public final class RedisBulkStringAggregator extends MessageAggregator<RedisMessage, BulkStringHeaderRedisMessage,
                                                                   BulkStringRedisContent, FullBulkStringRedisMessage> {
  
      /**
       * Creates a new instance.
       */
      public RedisBulkStringAggregator() {
          super(RedisConstants.REDIS_MESSAGE_MAX_LENGTH, RedisMessage.class);
      }
  
      @Override
      protected boolean isStartMessage(RedisMessage msg) throws Exception {
          return msg instanceof BulkStringHeaderRedisMessage && !isAggregated(msg);
      }
  
      @Override
      protected boolean isContentMessage(RedisMessage msg) throws Exception {
          return msg instanceof BulkStringRedisContent;
      }
  
      @Override
      protected boolean isLastContentMessage(BulkStringRedisContent msg) throws Exception {
          return msg instanceof LastBulkStringRedisContent;
      }
  
      @Override
      protected boolean isAggregated(RedisMessage msg) throws Exception {
          return msg instanceof FullBulkStringRedisMessage;
      }
  
      @Override
      protected boolean isContentLengthInvalid(BulkStringHeaderRedisMessage start, int maxContentLength)
              throws Exception {
          return start.bulkStringLength() > maxContentLength;
      }
  
      @Override
      protected Object newContinueResponse(BulkStringHeaderRedisMessage start, int maxContentLength,
                                           ChannelPipeline pipeline) throws Exception {
          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 FullBulkStringRedisMessage beginAggregation(BulkStringHeaderRedisMessage start, ByteBuf content)
              throws Exception {
          return new FullBulkStringRedisMessage(content);
      }
 }