/*
    * 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 java.util.HashMap;
  import java.util.Map;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.embedded.EmbeddedChannel;
  import io.netty.handler.codec.MessageToByteEncoder;
  import io.netty.handler.codec.compression.Brotli;
  import io.netty.handler.codec.compression.BrotliEncoder;
  import io.netty.handler.codec.compression.BrotliOptions;
  import io.netty.handler.codec.compression.CompressionOptions;
  import io.netty.handler.codec.compression.DeflateOptions;
  import io.netty.handler.codec.compression.GzipOptions;
  import io.netty.handler.codec.compression.StandardCompressionOptions;
  import io.netty.handler.codec.compression.ZlibCodecFactory;
  import io.netty.handler.codec.compression.ZlibEncoder;
  import io.netty.handler.codec.compression.ZlibWrapper;
  import io.netty.handler.codec.compression.Zstd;
  import io.netty.handler.codec.compression.ZstdEncoder;
  import io.netty.handler.codec.compression.ZstdOptions;
  import io.netty.util.internal.ObjectUtil;
  
  /**
   * Compresses an {@link HttpMessage} and an {@link HttpContent} in {@code gzip} or
   * {@code deflate} encoding while respecting the {@code "Accept-Encoding"} header.
   * If there is no matching encoding, no compression is done.  For more
   * information on how this handler modifies the message, please refer to
   * {@link HttpContentEncoder}.
   */
  public class HttpContentCompressor extends HttpContentEncoder {
  
      private final boolean supportsCompressionOptions;
      private final BrotliOptions brotliOptions;
      private final GzipOptions gzipOptions;
      private final DeflateOptions deflateOptions;
      private final ZstdOptions zstdOptions;
  
      private final int compressionLevel;
      private final int windowBits;
      private final int memLevel;
      private final int contentSizeThreshold;
      private ChannelHandlerContext ctx;
      private final Map<String, CompressionEncoderFactory> factories;
  
      /**
       * Creates a new handler with the default compression level (<tt>6</tt>),
       * default window size (<tt>15</tt>) and default memory level (<tt>8</tt>).
       */
      public HttpContentCompressor() {
          this(6);
      }
  
      /**
       * Creates a new handler with the specified compression level, default
       * window size (<tt>15</tt>) and default memory level (<tt>8</tt>).
       *
       * @param compressionLevel
       *        {@code 1} yields the fastest compression and {@code 9} yields the
       *        best compression.  {@code 0} means no compression.  The default
       *        compression level is {@code 6}.
       */
      @Deprecated
      public HttpContentCompressor(int compressionLevel) {
          this(compressionLevel, 15, 8, 0);
      }
  
      /**
       * Creates a new handler with the specified compression level, window size,
       * and memory level..
       *
       * @param compressionLevel
       *        {@code 1} yields the fastest compression and {@code 9} yields the
       *        best compression.  {@code 0} means no compression.  The default
       *        compression level is {@code 6}.
       * @param windowBits
       *        The base two logarithm of the size of the history buffer.  The
       *        value should be in the range {@code 9} to {@code 15} inclusive.
       *        Larger values result in better compression at the expense of
       *        memory usage.  The default value is {@code 15}.
       * @param memLevel
       *        How much memory should be allocated for the internal compression
       *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
      *        memory.  Larger values result in better and faster compression
      *        at the expense of memory usage.  The default value is {@code 8}
      */
     @Deprecated
     public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel) {
         this(compressionLevel, windowBits, memLevel, 0);
     }
 
     /**
      * Creates a new handler with the specified compression level, window size,
      * and memory level..
      *
      * @param compressionLevel
      *        {@code 1} yields the fastest compression and {@code 9} yields the
      *        best compression.  {@code 0} means no compression.  The default
      *        compression level is {@code 6}.
      * @param windowBits
      *        The base two logarithm of the size of the history buffer.  The
      *        value should be in the range {@code 9} to {@code 15} inclusive.
      *        Larger values result in better compression at the expense of
      *        memory usage.  The default value is {@code 15}.
      * @param memLevel
      *        How much memory should be allocated for the internal compression
      *        state.  {@code 1} uses minimum memory and {@code 9} uses maximum
      *        memory.  Larger values result in better and faster compression
      *        at the expense of memory usage.  The default value is {@code 8}
      * @param contentSizeThreshold
      *        The response body is compressed when the size of the response
      *        body exceeds the threshold. The value should be a non negative
      *        number. {@code 0} will enable compression for all responses.
      */
     @Deprecated
     public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel, int contentSizeThreshold) {
         this.compressionLevel = ObjectUtil.checkInRange(compressionLevel, 0, 9, "compressionLevel");
         this.windowBits = ObjectUtil.checkInRange(windowBits, 9, 15, "windowBits");
         this.memLevel = ObjectUtil.checkInRange(memLevel, 1, 9, "memLevel");
         this.contentSizeThreshold = ObjectUtil.checkPositiveOrZero(contentSizeThreshold, "contentSizeThreshold");
         this.brotliOptions = null;
         this.gzipOptions = null;
         this.deflateOptions = null;
         this.zstdOptions = null;
         this.factories = null;
         this.supportsCompressionOptions = false;
     }
 
     /**
      * Create a new {@link HttpContentCompressor} Instance with specified
      * {@link CompressionOptions}s and contentSizeThreshold set to {@code 0}
      *
      * @param compressionOptions {@link CompressionOptions} or {@code null} if the default
      *        should be used.
      */
     public HttpContentCompressor(CompressionOptions... compressionOptions) {
         this(0, compressionOptions);
     }
 
     /**
      * Create a new {@link HttpContentCompressor} instance with specified
      * {@link CompressionOptions}s
      *
      * @param contentSizeThreshold
      *        The response body is compressed when the size of the response
      *        body exceeds the threshold. The value should be a non negative
      *        number. {@code 0} will enable compression for all responses.
      * @param compressionOptions {@link CompressionOptions} or {@code null}
      *        if the default should be used.
      */
     public HttpContentCompressor(int contentSizeThreshold, CompressionOptions... compressionOptions) {
         this.contentSizeThreshold = ObjectUtil.checkPositiveOrZero(contentSizeThreshold, "contentSizeThreshold");
         BrotliOptions brotliOptions = null;
         GzipOptions gzipOptions = null;
         DeflateOptions deflateOptions = null;
         ZstdOptions zstdOptions = null;
         if (compressionOptions == null || compressionOptions.length == 0) {
             brotliOptions = Brotli.isAvailable() ? StandardCompressionOptions.brotli() : null;
             gzipOptions = StandardCompressionOptions.gzip();
             deflateOptions = StandardCompressionOptions.deflate();
             zstdOptions = Zstd.isAvailable() ? StandardCompressionOptions.zstd() : null;
         } else {
             ObjectUtil.deepCheckNotNull("compressionOptions", compressionOptions);
             for (CompressionOptions compressionOption : compressionOptions) {
                 // BrotliOptions' class initialization depends on Brotli classes being on the classpath.
                 // The Brotli.isAvailable check ensures that BrotliOptions will only get instantiated if Brotli is
                 // on the classpath.
                 // This results in the static analysis of native-image identifying the instanceof BrotliOptions check
                 // and thus BrotliOptions itself as unreachable, enabling native-image to link all classes
                 // at build time and not complain about the missing Brotli classes.
                 if (Brotli.isAvailable() && compressionOption instanceof BrotliOptions) {
                     brotliOptions = (BrotliOptions) compressionOption;
                 } else if (compressionOption instanceof GzipOptions) {
                     gzipOptions = (GzipOptions) compressionOption;
                 } else if (compressionOption instanceof DeflateOptions) {
                     deflateOptions = (DeflateOptions) compressionOption;
                 } else if (compressionOption instanceof ZstdOptions) {
                     zstdOptions = (ZstdOptions) compressionOption;
                 } else {
                     throw new IllegalArgumentException("Unsupported " + CompressionOptions.class.getSimpleName() +
                             ": " + compressionOption);
                 }
             }
         }
 
         this.gzipOptions = gzipOptions;
         this.deflateOptions = deflateOptions;
         this.brotliOptions = brotliOptions;
         this.zstdOptions = zstdOptions;
 
         this.factories = new HashMap<String, CompressionEncoderFactory>();
 
         if (this.gzipOptions != null) {
             this.factories.put("gzip", new GzipEncoderFactory());
         }
         if (this.deflateOptions != null) {
             this.factories.put("deflate", new DeflateEncoderFactory());
         }
         if (Brotli.isAvailable() && this.brotliOptions != null) {
             this.factories.put("br", new BrEncoderFactory());
         }
         if (this.zstdOptions != null) {
             this.factories.put("zstd", new ZstdEncoderFactory());
         }
 
         this.compressionLevel = -1;
         this.windowBits = -1;
         this.memLevel = -1;
         supportsCompressionOptions = true;
     }
 
     @Override
     public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
         this.ctx = ctx;
     }
 
     @Override
     protected Result beginEncode(HttpResponse httpResponse, String acceptEncoding) throws Exception {
         if (this.contentSizeThreshold > 0) {
             if (httpResponse instanceof HttpContent &&
                     ((HttpContent) httpResponse).content().readableBytes() < contentSizeThreshold) {
                 return null;
             }
         }
 
         String contentEncoding = httpResponse.headers().get(HttpHeaderNames.CONTENT_ENCODING);
         if (contentEncoding != null) {
             // Content-Encoding was set, either as something specific or as the IDENTITY encoding
             // Therefore, we should NOT encode here
             return null;
         }
 
         if (supportsCompressionOptions) {
             String targetContentEncoding = determineEncoding(acceptEncoding);
             if (targetContentEncoding == null) {
                 return null;
             }
 
             CompressionEncoderFactory encoderFactory = factories.get(targetContentEncoding);
 
             if (encoderFactory == null) {
                 throw new Error();
             }
 
             return new Result(targetContentEncoding,
                     new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                             ctx.channel().config(), encoderFactory.createEncoder()));
         } else {
             ZlibWrapper wrapper = determineWrapper(acceptEncoding);
             if (wrapper == null) {
                 return null;
             }
 
             String targetContentEncoding;
             switch (wrapper) {
                 case GZIP:
                     targetContentEncoding = "gzip";
                     break;
                 case ZLIB:
                     targetContentEncoding = "deflate";
                     break;
                 default:
                     throw new Error();
             }
 
             return new Result(
                     targetContentEncoding,
                     new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
                             ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
                             wrapper, compressionLevel, windowBits, memLevel)));
         }
     }
 
     @SuppressWarnings("FloatingPointEquality")
     protected String determineEncoding(String acceptEncoding) {
         float starQ = -1.0f;
         float brQ = -1.0f;
         float zstdQ = -1.0f;
         float gzipQ = -1.0f;
         float deflateQ = -1.0f;
         for (String encoding : acceptEncoding.split(",")) {
             float q = 1.0f;
             int equalsPos = encoding.indexOf('=');
             if (equalsPos != -1) {
                 try {
                     q = Float.parseFloat(encoding.substring(equalsPos + 1));
                 } catch (NumberFormatException e) {
                     // Ignore encoding
                     q = 0.0f;
                 }
             }
             if (encoding.contains("*")) {
                 starQ = q;
             } else if (encoding.contains("br") && q > brQ) {
                 brQ = q;
             } else if (encoding.contains("zstd") && q > zstdQ) {
                 zstdQ = q;
             } else if (encoding.contains("gzip") && q > gzipQ) {
                 gzipQ = q;
             } else if (encoding.contains("deflate") && q > deflateQ) {
                 deflateQ = q;
             }
         }
         if (brQ > 0.0f || zstdQ > 0.0f || gzipQ > 0.0f || deflateQ > 0.0f) {
             if (brQ != -1.0f && brQ >= zstdQ && this.brotliOptions != null) {
                 return "br";
             } else if (zstdQ != -1.0f && zstdQ >= gzipQ && this.zstdOptions != null) {
                 return "zstd";
             } else if (gzipQ != -1.0f && gzipQ >= deflateQ && this.gzipOptions != null) {
                 return "gzip";
             } else if (deflateQ != -1.0f && this.deflateOptions != null) {
                 return "deflate";
             }
         }
         if (starQ > 0.0f) {
             if (brQ == -1.0f && this.brotliOptions != null) {
                 return "br";
             }
             if (zstdQ == -1.0f && this.zstdOptions != null) {
                 return "zstd";
             }
             if (gzipQ == -1.0f && this.gzipOptions != null) {
                 return "gzip";
             }
             if (deflateQ == -1.0f && this.deflateOptions != null) {
                 return "deflate";
             }
         }
         return null;
     }
 
     @Deprecated
     @SuppressWarnings("FloatingPointEquality")
     protected ZlibWrapper determineWrapper(String acceptEncoding) {
         float starQ = -1.0f;
         float gzipQ = -1.0f;
         float deflateQ = -1.0f;
         for (String encoding : acceptEncoding.split(",")) {
             float q = 1.0f;
             int equalsPos = encoding.indexOf('=');
             if (equalsPos != -1) {
                 try {
                     q = Float.parseFloat(encoding.substring(equalsPos + 1));
                 } catch (NumberFormatException e) {
                     // Ignore encoding
                     q = 0.0f;
                 }
             }
             if (encoding.contains("*")) {
                 starQ = q;
             } else if (encoding.contains("gzip") && q > gzipQ) {
                 gzipQ = q;
             } else if (encoding.contains("deflate") && q > deflateQ) {
                 deflateQ = q;
             }
         }
         if (gzipQ > 0.0f || deflateQ > 0.0f) {
             if (gzipQ >= deflateQ) {
                 return ZlibWrapper.GZIP;
             } else {
                 return ZlibWrapper.ZLIB;
             }
         }
         if (starQ > 0.0f) {
             if (gzipQ == -1.0f) {
                 return ZlibWrapper.GZIP;
             }
             if (deflateQ == -1.0f) {
                 return ZlibWrapper.ZLIB;
             }
         }
         return null;
     }
 
     /**
      * Compression Encoder Factory that creates {@link ZlibEncoder}s
      * used to compress http content for gzip content encoding
      */
     private final class GzipEncoderFactory implements CompressionEncoderFactory {
 
         @Override
         public MessageToByteEncoder<ByteBuf> createEncoder() {
             return ZlibCodecFactory.newZlibEncoder(
                     ZlibWrapper.GZIP, gzipOptions.compressionLevel(),
                     gzipOptions.windowBits(), gzipOptions.memLevel());
         }
     }
 
     /**
      * Compression Encoder Factory that creates {@link ZlibEncoder}s
      * used to compress http content for deflate content encoding
      */
     private final class DeflateEncoderFactory implements CompressionEncoderFactory {
 
         @Override
         public MessageToByteEncoder<ByteBuf> createEncoder() {
             return ZlibCodecFactory.newZlibEncoder(
                     ZlibWrapper.ZLIB, deflateOptions.compressionLevel(),
                     deflateOptions.windowBits(), deflateOptions.memLevel());
         }
     }
 
     /**
      * Compression Encoder Factory that creates {@link BrotliEncoder}s
      * used to compress http content for br content encoding
      */
     private final class BrEncoderFactory implements CompressionEncoderFactory {
 
         @Override
         public MessageToByteEncoder<ByteBuf> createEncoder() {
             return new BrotliEncoder(brotliOptions.parameters());
         }
     }
 
     /**
      * Compression Encoder Factory for create {@link ZstdEncoder}
      * used to compress http content for zstd content encoding
      */
     private final class ZstdEncoderFactory implements CompressionEncoderFactory {
 
         @Override
         public MessageToByteEncoder<ByteBuf> createEncoder() {
             return new ZstdEncoder(zstdOptions.compressionLevel(),
                     zstdOptions.blockSize(), zstdOptions.maxEncodeSize());
         }
     }
 }