content: /*
   * Copyright 2002-2019 Drew Noakes and contributors
   *
   *    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
   *
   *        https://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.
   *
   * More information about this project is available at:
   *
   *    https://drewnoakes.com/code/exif/
   *    https://github.com/drewnoakes/metadata-extractor
   */
  package com.drew.imaging.riff;
  
  import com.drew.lang.SequentialReader;
  import com.drew.lang.annotations.NotNull;
  
  import java.io.IOException;
  
  /**
   * Processes RIFF-formatted data, calling into client code via that {@link RiffHandler} interface.
   * <p></p>
   * For information on this file format, see:
   * <ul>
   *     <li>https://en.wikipedia.org/wiki/Resource_Interchange_File_Format</li>
   *     <li>https://developers.google.com/speed/webp/docs/riff_container</li>
   *     <li>https://www.daubnet.com/en/file-format-riff</li>
   * </ul>
   * @author Drew Noakes https://drewnoakes.com
   * @author Payton Garland
   */
  public class RiffReader
  {
      /**
       * Processes a RIFF data sequence.
       *
       * @param reader the {@link SequentialReader} from which the data should be read
       * @param handler the {@link RiffHandler} that will coordinate processing and accept read values
       * @throws RiffProcessingException if an error occurred during the processing of RIFF data that could not be
       *                                 ignored or recovered from
       * @throws IOException an error occurred while accessing the required data
       */
      public void processRiff(@NotNull final SequentialReader reader,
                              @NotNull final RiffHandler handler) throws RiffProcessingException, IOException
      {
          // RIFF files are always little-endian
          reader.setMotorolaByteOrder(false);
  
          // PROCESS FILE HEADER
  
          final String fileFourCC = reader.getString(4);
  
          if (!fileFourCC.equals("RIFF"))
              throw new RiffProcessingException("Invalid RIFF header: " + fileFourCC);
  
          // The total size of the chunks that follow plus 4 bytes for the FourCC
          final int fileSize = reader.getInt32();
          int sizeLeft = fileSize;
  
          final String identifier = reader.getString(4);
          sizeLeft -= 4;
  
          if (!handler.shouldAcceptRiffIdentifier(identifier))
              return;
  
          // PROCESS CHUNKS
          processChunks(reader, sizeLeft, handler);
      }
  
      public void processChunks(SequentialReader reader, int sectionSize, RiffHandler handler) throws IOException
      {
          try {
              while (reader.getPosition() < sectionSize) {
                  String fourCC = new String(reader.getBytes(4));
                  int size = reader.getInt32();
                  if (size <= 0) {
                      handler.addError("Invalid chunk size: " + size);
                      break;
                  }
                  if (fourCC.equals("LIST") || fourCC.equals("RIFF")) {
                      String listName = new String(reader.getBytes(4));
                      if (size < 4) {
                          handler.addError("Chunk size too small.");
                      } else {
                          if (handler.shouldAcceptList(listName)) {
                              processChunks(reader, size - 4, handler);
                          } else {
                              reader.skip(size - 4);
                          }
                      }
                  } else if (fourCC.equals("IDIT")) {
                      // Avi DateTimeOriginal
                      if (size < 2) {
                          handler.addError("Chunk size too small.");
                      } else {
                          handler.processChunk(fourCC, reader.getBytes(size - 2));
                          reader.skip(2); // ?0A 00?
                      }
                  } else {
                      if (handler.shouldAcceptChunk(fourCC)) {
                          // TODO is it feasible to avoid copying the chunk here, and to pass the sequential reader to the handler?
                          handler.processChunk(fourCC, reader.getBytes(size));
                      } else {
                          reader.skip(size);
                      }
                      // Bytes read must be even - skip one if not
                      if ((size & 1) == 1) {
                          reader.skip(1);
                      }
                  }
              }
          } catch (IOException e) {
              handler.addError(e.getMessage());
          }
      }
  }
  