/*
    * Copyright 2012 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;
  
  import io.netty.channel.Channel;
  import io.netty.channel.embedded.EmbeddedChannel;
  import io.netty.handler.codec.compression.Brotli;
  import io.netty.handler.codec.compression.BrotliDecoder;
  import io.netty.handler.codec.compression.SnappyFrameDecoder;
  import io.netty.handler.codec.compression.ZlibCodecFactory;
  import io.netty.handler.codec.compression.ZlibWrapper;
  import io.netty.handler.codec.compression.Zstd;
  import io.netty.handler.codec.compression.ZstdDecoder;
  
  import static io.netty.handler.codec.http.HttpHeaderValues.BR;
  import static io.netty.handler.codec.http.HttpHeaderValues.DEFLATE;
  import static io.netty.handler.codec.http.HttpHeaderValues.GZIP;
  import static io.netty.handler.codec.http.HttpHeaderValues.SNAPPY;
  import static io.netty.handler.codec.http.HttpHeaderValues.X_DEFLATE;
  import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
  import static io.netty.handler.codec.http.HttpHeaderValues.ZSTD;
  import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
  
  /**
   * Decompresses an {@link HttpMessage} and an {@link HttpContent} compressed in
   * {@code gzip} or {@code deflate} encoding.  For more information on how this
   * handler modifies the message, please refer to {@link HttpContentDecoder}.
   */
  public class HttpContentDecompressor extends HttpContentDecoder {
  
      private final boolean strict;
      private final int maxAllocation;
  
      /**
       * Create a new {@link HttpContentDecompressor} in non-strict mode.
       * @deprecated
       *            Use {@link HttpContentDecompressor#HttpContentDecompressor(int)}.
       */
      @Deprecated
      public HttpContentDecompressor() {
          this(false, 0);
      }
  
      /**
       * Create a new {@link HttpContentDecompressor} in non-strict mode.
       * @param maxAllocation
       *            Maximum size of the decompression buffer. Must be >= 0. If zero, maximum size is not limited.
       */
      public HttpContentDecompressor(int maxAllocation) {
          this(false, maxAllocation);
      }
  
      /**
       * Create a new {@link HttpContentDecompressor}.
       *
       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
       *                  more lenient fashion.
       * @deprecated
       *            Use {@link HttpContentDecompressor#HttpContentDecompressor(boolean, int)}.
       */
      @Deprecated
      public HttpContentDecompressor(boolean strict) {
          this(strict, 0);
      }
  
      /**
       * Create a new {@link HttpContentDecompressor}.
       *
       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
       *                  more lenient fashion.
       * @param maxAllocation
       *             Maximum size of the decompression buffer. Must be >= 0. If zero, maximum size is not limited.
       */
      public HttpContentDecompressor(boolean strict, int maxAllocation) {
          this.strict = strict;
          this.maxAllocation = checkPositiveOrZero(maxAllocation, "maxAllocation");
      }
  
      @Override
      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
          Channel channel = ctx.channel();
          if (GZIP.contentEqualsIgnoreCase(contentEncoding) ||
              X_GZIP.contentEqualsIgnoreCase(contentEncoding)) {
              return EmbeddedChannel.builder()
                      .channelId(channel.id())
                      .hasDisconnect(channel.metadata().hasDisconnect())
                     .config(channel.config())
                     .handlers(ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP, maxAllocation))
                     .build();
         }
         if (DEFLATE.contentEqualsIgnoreCase(contentEncoding) ||
             X_DEFLATE.contentEqualsIgnoreCase(contentEncoding)) {
             final ZlibWrapper wrapper = strict ? ZlibWrapper.ZLIB : ZlibWrapper.ZLIB_OR_NONE;
             // To be strict, 'deflate' means ZLIB, but some servers were not implemented correctly.
             return EmbeddedChannel.builder()
                     .channelId(channel.id())
                     .hasDisconnect(channel.metadata().hasDisconnect())
                     .config(channel.config())
                     .handlers(ZlibCodecFactory.newZlibDecoder(wrapper, maxAllocation))
                     .build();
         }
         if (Brotli.isAvailable() && BR.contentEqualsIgnoreCase(contentEncoding)) {
             return EmbeddedChannel.builder()
                     .channelId(channel.id())
                     .hasDisconnect(channel.metadata().hasDisconnect())
                     .config(channel.config())
                     .handlers(new BrotliDecoder())
                     .build();
         }
 
         if (SNAPPY.contentEqualsIgnoreCase(contentEncoding)) {
             return EmbeddedChannel.builder()
                     .channelId(channel.id())
                     .hasDisconnect(channel.metadata().hasDisconnect())
                     .config(channel.config())
                     .handlers(new SnappyFrameDecoder())
                     .build();
         }
 
         if (Zstd.isAvailable() && ZSTD.contentEqualsIgnoreCase(contentEncoding)) {
             return EmbeddedChannel.builder()
                     .channelId(channel.id())
                     .hasDisconnect(channel.metadata().hasDisconnect())
                     .config(channel.config())
                     .handlers(new ZstdDecoder())
                     .build();
         }
 
         // 'identity' or unsupported
         return null;
     }
 }