content: /*
   * Licensed 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
   *
   *     http://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.airlift.compress.v3.deflate;
  
  import io.airlift.compress.v3.Compressor;
  
  import java.lang.foreign.MemorySegment;
  import java.util.zip.Deflater;
  
  import static java.lang.Math.toIntExact;
  import static java.util.Objects.requireNonNull;
  import static java.util.zip.Deflater.FULL_FLUSH;
  
  public class DeflateCompressor
          implements Compressor
  {
      private static final int EXTRA_COMPRESSION_SPACE = 16;
      private static final int COMPRESSION_LEVEL = 4;
  
      private final int compressionLevel;
  
      public DeflateCompressor()
      {
          this(COMPRESSION_LEVEL);
      }
  
      public DeflateCompressor(int compressionLevel)
      {
          if (compressionLevel < 0 || compressionLevel > 9) {
              throw new IllegalArgumentException("Invalid compression level: %d (must be 0-9)".formatted(compressionLevel));
          }
          this.compressionLevel = compressionLevel;
      }
  
      @Override
      public int maxCompressedLength(int uncompressedSize)
      {
          // From Mark Adler's post http://stackoverflow.com/questions/1207877/java-size-of-compression-output-bytearray
          return uncompressedSize + ((uncompressedSize + 7) >> 3) + ((uncompressedSize + 63) >> 6) + 5 + EXTRA_COMPRESSION_SPACE;
      }
  
      @Override
      public int compress(byte[] input, int inputOffset, int inputLength, byte[] output, int outputOffset, int maxOutputLength)
      {
          verifyRange(input, inputOffset, inputLength);
          verifyRange(output, outputOffset, maxOutputLength);
  
          Deflater deflater = new Deflater(compressionLevel, true);
          try {
              deflater.setInput(input, inputOffset, inputLength);
              deflater.finish();
  
              int compressedDataLength = deflater.deflate(output, outputOffset, maxOutputLength, FULL_FLUSH);
              if (!deflater.finished()) {
                  throw new IllegalStateException("Output buffer too small");
              }
              return compressedDataLength;
          }
          finally {
              deflater.end();
          }
      }
  
      @Override
      public int compress(MemorySegment input, MemorySegment output)
      {
          int maxCompressedLength = maxCompressedLength(toIntExact(input.byteSize()));
          if (output.byteSize() < maxCompressedLength) {
              throw new IllegalArgumentException("Output buffer must be at least " + maxCompressedLength + " bytes");
          }
  
          Deflater deflater = new Deflater(compressionLevel, true);
          try {
              deflater.setInput(input.asByteBuffer());
              deflater.finish();
  
              int compressedDataLength = deflater.deflate(output.asByteBuffer(), FULL_FLUSH);
              if (!deflater.finished()) {
                  throw new IllegalStateException("maxCompressedLength formula is incorrect, because deflate produced more data");
              }
              return compressedDataLength;
          }
          finally {
              deflater.end();
          }
      }
  
      private static void verifyRange(byte[] data, int offset, int length)
      {
          requireNonNull(data, "data is null");
          if (offset < 0 || length < 0 || offset + length > data.length) {
              throw new IllegalArgumentException("Invalid offset or length (%s, %s) in array of length %s".formatted(offset, length, data.length));
          }
      }
  }
  