content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF 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
   *
   *        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 org.apache.causeway.commons.internal.base;
  
  import java.io.IOException;
  import java.util.Arrays;
  
  import org.apache.causeway.commons.internal.exceptions._Exceptions;
  
  import lombok.experimental.UtilityClass;
  
  /**
   * package private utility for {@link _Bytes}
   */
  @UtilityClass
  class _Bytes_GZipCompressorSmart {
  
      private static final int INPUT_LENGTH_THRESHOLD_FOR_SMART_COMPRESSION = 256;
      private static final int GZIP_MIN_OVERHEAD = 18;
      private static final byte COMPRESSION_NONE = 0;
      private static final byte COMPRESSION_GZIP = 1;
  
      byte[] compress(final byte[] input) throws IOException {
          if(input.length<GZIP_MIN_OVERHEAD) {
              return input;
          }
          if(input.length<INPUT_LENGTH_THRESHOLD_FOR_SMART_COMPRESSION) {
              return _Bytes.prepend(input, COMPRESSION_NONE); // prefix the input
          } else {
              return _Bytes.prepend(_Bytes_GZipCompressor.compress(input), COMPRESSION_GZIP); // prefix the input
          }
      }
  
      byte[] decompress(final byte[] input) throws IOException {
          if(input==null || input.length<GZIP_MIN_OVERHEAD)
              return input;
  
          final byte[] inputWithoutPrefix = Arrays.copyOfRange(input, 1, input.length);
  
          return isCompressed(input) ? _Bytes_GZipCompressor.decompress(inputWithoutPrefix) : inputWithoutPrefix;
  
      }
  
      // -- HELPER
  
      private boolean isCompressed(final byte[] input) {
          switch (input[0]) {
          case COMPRESSION_NONE:
              return false;
          case COMPRESSION_GZIP:
              return true;
          default:
              throw _Exceptions.unmatchedCase(input[0]);
          }
  
      }
  
  }
  