/*
    * 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.commons.imaging.formats.png.chunks;
  
  import java.io.ByteArrayInputStream;
  import java.io.IOException;
  import java.nio.charset.StandardCharsets;
  import java.util.zip.InflaterInputStream;
  
  import org.apache.commons.imaging.ImagingException;
  import org.apache.commons.imaging.common.Allocator;
  import org.apache.commons.imaging.common.BinaryFunctions;
  import org.apache.commons.imaging.formats.png.AbstractPngText;
  import org.apache.commons.imaging.formats.png.PngConstants;
  import org.apache.commons.io.IOUtils;
  
  public class PngChunkZtxt extends AbstractPngTextChunk {
  
      private final String keyword;
      private final String text;
  
      public PngChunkZtxt(final int length, final int chunkType, final int crc, final byte[] bytes) throws ImagingException, IOException {
          super(length, chunkType, crc, bytes);
  
          int index = BinaryFunctions.findNull(bytes, "PNG zTXt chunk keyword is unterminated.");
          keyword = new String(bytes, 0, index, StandardCharsets.ISO_8859_1);
          index++;
  
          final int compressionMethod = bytes[index++];
          if (compressionMethod != PngConstants.COMPRESSION_DEFLATE_INFLATE) {
              throw new ImagingException("PNG zTXt chunk has unexpected compression method: " + compressionMethod);
          }
  
          final int compressedTextLength = bytes.length - index;
          final byte[] compressedText = Allocator.byteArray(compressedTextLength);
          System.arraycopy(bytes, index, compressedText, 0, compressedTextLength);
  
          text = new String(IOUtils.toByteArray(new InflaterInputStream(new ByteArrayInputStream(compressedText))), StandardCharsets.ISO_8859_1);
      }
  
      @Override
      public AbstractPngText getContents() {
          return new AbstractPngText.Ztxt(keyword, text);
      }
  
      /**
       * Gets the keyword.
       *
       * @return the keyword.
       */
      @Override
      public String getKeyword() {
          return keyword;
      }
  
      /**
       * Gets the text.
       *
       * @return the text.
       */
      @Override
      public String getText() {
          return text;
      }
  
  }