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.zstd;
  
  import io.airlift.compress.v3.MalformedInputException;
  
  import java.lang.foreign.MemorySegment;
  
  import static java.lang.String.format;
  import static java.util.Arrays.copyOfRange;
  import static java.util.Objects.requireNonNull;
  import static org.assertj.core.api.Assertions.assertThat;
  import static sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
  
  public class ZstdPartialDecompressor
          implements ZstdDecompressor
  {
      private final ZstdIncrementalFrameDecompressor decompressor = new ZstdIncrementalFrameDecompressor();
  
      @Override
      public int decompress(final byte[] input, final int inputOffset, final int inputLength, final byte[] output, final int outputOffset, final int maxOutputLength)
              throws MalformedInputException
      {
          verifyRange(input, inputOffset, inputLength);
          verifyRange(output, outputOffset, maxOutputLength);
  
          assertThat(decompressor.getInputRequired()).isEqualTo(0);
          assertThat(decompressor.getRequestedOutputSize()).isEqualTo(0);
          assertThat(decompressor.getInputConsumed()).isEqualTo(0);
          assertThat(decompressor.getOutputBufferUsed()).isEqualTo(0);
  
          int inputPosition = inputOffset;
          final int inputLimit = inputOffset + inputLength;
          int outputPosition = outputOffset;
          final int outputLimit = outputOffset + maxOutputLength;
  
          while (inputPosition < inputLimit || decompressor.getRequestedOutputSize() > 0) {
              if (decompressor.getInputRequired() > inputLimit - inputPosition) {
                  // the non-partial tests verify the exact exception type, so just throw that exception
                  throw new MalformedInputException(inputPosition, "Not enough input bytes");
              }
              if (outputPosition + decompressor.getRequestedOutputSize() > outputLimit) {
                  throw new IllegalArgumentException("Output buffer too small");
              }
  
              // for testing, we always send the minimum number of requested bytes
              byte[] inputChunk = copyOfRange(input, inputPosition, inputPosition + decompressor.getInputRequired());
  
              // for testing, we use two reads for larger buffers
              byte[] outputBuffer = new byte[0];
              if (decompressor.getRequestedOutputSize() > 0) {
                  outputBuffer = new byte[decompressor.getRequestedOutputSize() > 500 ? decompressor.getRequestedOutputSize() - 457 : decompressor.getRequestedOutputSize()];
              }
  
              decompressor.partialDecompress(
                      inputChunk,
                      ARRAY_BYTE_BASE_OFFSET,
                      inputChunk.length + ARRAY_BYTE_BASE_OFFSET,
                      outputBuffer,
                      0,
                      outputBuffer.length);
  
              // copy output chunk to output
              int outputBufferUsed = decompressor.getOutputBufferUsed();
              if (outputBufferUsed > 0) {
                  assertThat(outputPosition + outputBufferUsed <= outputLimit).isTrue();
                  System.arraycopy(outputBuffer, 0, output, outputPosition, outputBufferUsed);
                  outputPosition += outputBufferUsed;
              }
  
              assertThat(decompressor.getInputConsumed() <= inputChunk.length).isTrue();
              inputPosition += decompressor.getInputConsumed();
          }
          return outputPosition - outputOffset;
      }
  
      @Override
      public int decompress(MemorySegment input, MemorySegment output)
              throws MalformedInputException
      {
          throw new UnsupportedOperationException("not yet implemented");
      }
  
      @Override
      public long getDecompressedSize(byte[] input, int offset, int length)
      {
          int baseAddress = ARRAY_BYTE_BASE_OFFSET + offset;
          return ZstdFrameDecompressor.getDecompressedSize(input, baseAddress, baseAddress + length);
      }
  
      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(format("Invalid offset or length (%s, %s) in array of length %s", offset, length, data.length));
          }
      }
  }
  