/*
    * 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 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.X_DEFLATE;
  import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
  import static io.netty.handler.codec.http.HttpHeaderValues.SNAPPY;
  import static io.netty.handler.codec.http.HttpHeaderValues.ZSTD;
  
  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;
  
  /**
   * 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;
  
      /**
       * Create a new {@link HttpContentDecompressor} in non-strict mode.
       */
      public HttpContentDecompressor() {
          this(false);
      }
  
      /**
       * 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.
       */
      public HttpContentDecompressor(boolean strict) {
          this.strict = strict;
      }
  
      @Override
      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
          if (GZIP.contentEqualsIgnoreCase(contentEncoding) ||
              X_GZIP.contentEqualsIgnoreCase(contentEncoding)) {
              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
          }
          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 new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(wrapper));
          }
          if (Brotli.isAvailable() && BR.contentEqualsIgnoreCase(contentEncoding)) {
              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                ctx.channel().config(), new BrotliDecoder());
          }
  
          if (SNAPPY.contentEqualsIgnoreCase(contentEncoding)) {
              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                      ctx.channel().config(), new SnappyFrameDecoder());
          }
  
          if (Zstd.isAvailable() && ZSTD.contentEqualsIgnoreCase(contentEncoding)) {
              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                      ctx.channel().config(), new ZstdDecoder());
          }
  
          // 'identity' or unsupported
          return null;
      }
  }