/*
    * 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 final class PngChunkItxt extends AbstractPngTextChunk {
  
      private final String keyword;
      private final String text;
  
      /**
       * The language tag defined in [RFC-3066] indicates the human language used by the translated keyword and the text. Unlike the keyword, the language tag is
       * case-insensitive. It is an ISO 646.IRV:1991 [ISO 646] string consisting of hyphen-separated words of 1-8 alphanumeric characters each (for example cn,
       * en-uk, no-bok, x-klingon, x-KlInGoN). If the first word is two or three letters long, it is an ISO language code [ISO-639]. If the language tag is empty,
       * the language is unspecified.
       */
      private final String languageTag;
  
      private final String translatedKeyword;
  
      /**
       * Constructs a new instance.
       *
       * @param length    chunk length.
       * @param chunkType chunk type.
       * @param crc       CRC computed over the chunk type and chunk data (but not the length).
       * @param bytes     chunk data bytes.
       * @throws ImagingException Thrown on a parsing error.
       * @throws IOException Thrown on reading error.
       * @throws NullPointerException if {@code bytes} is null.
       */
      public PngChunkItxt(final int length, final int chunkType, final int crc, final byte[] bytes) throws ImagingException, IOException {
          super(length, chunkType, crc, bytes);
          int terminator = BinaryFunctions.indexOf0(bytes, "PNG iTXt chunk keyword is not terminated.");
  
          keyword = new String(bytes, 0, terminator, StandardCharsets.ISO_8859_1);
          int index = terminator + 1;
  
          final int compressionFlag = bytes[index++];
          if (compressionFlag != 0 && compressionFlag != 1) {
              throw new ImagingException("PNG iTXt chunk has invalid compression flag: " + compressionFlag);
          }
  
          final boolean compressed = compressionFlag == 1;
  
          final int compressionMethod = bytes[index++];
          if (compressed && compressionMethod != PngConstants.COMPRESSION_DEFLATE_INFLATE) {
              throw new ImagingException("PNG iTXt chunk has unexpected compression method: " + compressionMethod);
          }
  
          terminator = BinaryFunctions.indexOf0(bytes, index, "PNG iTXt chunk language tag is not terminated.");
          languageTag = new String(bytes, index, terminator - index, StandardCharsets.ISO_8859_1);
          index = terminator + 1;
  
          terminator = BinaryFunctions.indexOf0(bytes, index, "PNG iTXt chunk translated keyword is not terminated.");
          translatedKeyword = new String(bytes, index, terminator - index, StandardCharsets.UTF_8);
          index = terminator + 1;
  
          if (compressed) {
              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.UTF_8);
  
          } else {
              text = new String(bytes, index, bytes.length - index, StandardCharsets.UTF_8);
          }
      }
  
      @Override
      public AbstractPngText getContents() {
          return new AbstractPngText.Itxt(keyword, text, languageTag, translatedKeyword);
     }
 
     /**
      * @return Gets the keyword.
      */
     @Override
     public String getKeyword() {
         return keyword;
     }
 
     /**
      * @return Gets the text.
      */
     @Override
     public String getText() {
         return text;
     }
 
     public String getTranslatedKeyword() {
         return translatedKeyword;
     }
 }