content: /*
   * Copyright 2002-2012 Drew Noakes
   *
   *    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.
   *
   * More information about this project is available at:
   *
   *    http://drewnoakes.com/code/exif/
   *    http://code.google.com/p/metadata-extractor/
   */
  package com.almalence.util.exifreader.imaging.jpeg;
  
  import com.almalence.util.exifreader.lang.annotations.NotNull;
  import com.almalence.util.exifreader.lang.annotations.Nullable;
  
  import java.io.*;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  
  /**
   * Holds a collection of Jpeg data segments.  This need not necessarily be all segments
   * within the Jpeg.  For example, it may be convenient to store only the non-image
   * segments when analysing (or serializing) metadata.
   * <p/>
   * Segments are keyed via their segment marker (a byte).  Where multiple segments use the
   * same segment marker, they will all be stored and available.
   *
   * @author Drew Noakes http://drewnoakes.com
   */
  public class JpegSegmentData implements Serializable
  {
      private static final long serialVersionUID = 7110175216435025451L;
      
      /** A map of byte[], keyed by the segment marker */
      @NotNull
      private final HashMap<Byte, List<byte[]>> _segmentDataMap = new HashMap<Byte, List<byte[]>>(10);
  
      /**
       * Adds segment bytes to the collection.
       * @param segmentMarker
       * @param segmentBytes
       */
      @SuppressWarnings({ "MismatchedQueryAndUpdateOfCollection" })
      public void addSegment(byte segmentMarker, @NotNull byte[] segmentBytes)
      {
          final List<byte[]> segmentList = getOrCreateSegmentList(segmentMarker);
          segmentList.add(segmentBytes);
      }
  
      /**
       * Gets the first Jpeg segment data for the specified marker.
       * @param segmentMarker the byte identifier for the desired segment
       * @return a byte[] containing segment data or null if no data exists for that segment
       */
      @Nullable
      public byte[] getSegment(byte segmentMarker)
      {
          return getSegment(segmentMarker, 0);
      }
  
      /**
       * Gets segment data for a specific occurrence and marker.  Use this method when more than one occurrence
       * of segment data for a given marker exists.
       * @param segmentMarker identifies the required segment
       * @param occurrence the zero-based index of the occurrence
       * @return the segment data as a byte[], or null if no segment exists for the marker & occurrence
       */
      @Nullable
      public byte[] getSegment(byte segmentMarker, int occurrence)
      {
          final List<byte[]> segmentList = getSegmentList(segmentMarker);
  
          if (segmentList==null || segmentList.size()<=occurrence)
              return null;
          else
              return segmentList.get(occurrence);
      }
  
      /**
       * Returns all instances of a given Jpeg segment.  If no instances exist, an empty sequence is returned.
       *
       * @param segmentMarker a number which identifies the type of Jpeg segment being queried
       * @return zero or more byte arrays, each holding the data of a Jpeg segment
       */
      @NotNull
      public Iterable<byte[]> getSegments(byte segmentMarker)
      {
          final List<byte[]> segmentList = getSegmentList(segmentMarker);
          return segmentList==null ? new ArrayList<byte[]>() : segmentList;
      }
  
      @Nullable
      public List<byte[]> getSegmentList(byte segmentMarker)
      {
          return _segmentDataMap.get(Byte.valueOf(segmentMarker));
      }
  
      @NotNull
      private List<byte[]> getOrCreateSegmentList(byte segmentMarker)
      {
          List<byte[]> segmentList;
          if (_segmentDataMap.containsKey(segmentMarker)) {
              segmentList = _segmentDataMap.get(segmentMarker);
          } else {
              segmentList = new ArrayList<byte[]>();
              _segmentDataMap.put(segmentMarker, segmentList);
          }
          return segmentList;
      }
  
      /**
       * Returns the count of segment data byte arrays stored for a given segment marker.
       * @param segmentMarker identifies the required segment
       * @return the segment count (zero if no segments exist).
       */
      public int getSegmentCount(byte segmentMarker)
      {
          final List<byte[]> segmentList = getSegmentList(segmentMarker);
          return segmentList == null ? 0 : segmentList.size();
      }
  
      /**
       * Removes a specified instance of a segment's data from the collection.  Use this method when more than one
       * occurrence of segment data for a given marker exists.
       * @param segmentMarker identifies the required segment
       * @param occurrence the zero-based index of the segment occurrence to remove.
       */
      @SuppressWarnings({ "MismatchedQueryAndUpdateOfCollection" })
      public void removeSegmentOccurrence(byte segmentMarker, int occurrence)
      {
          final List<byte[]> segmentList = _segmentDataMap.get(Byte.valueOf(segmentMarker));
          segmentList.remove(occurrence);
      }
  
      /**
       * Removes all segments from the collection having the specified marker.
       * @param segmentMarker identifies the required segment
       */
      public void removeSegment(byte segmentMarker)
      {
          _segmentDataMap.remove(Byte.valueOf(segmentMarker));
      }
  
      /**
       * Determines whether data is present for a given segment marker.
       * @param segmentMarker identifies the required segment
       * @return true if data exists, otherwise false
       */
      public boolean containsSegment(byte segmentMarker)
      {
          return _segmentDataMap.containsKey(Byte.valueOf(segmentMarker));
      }
  
      /**
       * Serialises the contents of a JpegSegmentData to a file.
       * @param file to file to write from
       * @param segmentData the data to write
       * @throws IOException if problems occur while writing
       */
      public static void toFile(@NotNull File file, @NotNull JpegSegmentData segmentData) throws IOException
      {
          FileOutputStream fileOutputStream = null;
          try
          {
              fileOutputStream = new FileOutputStream(file);
              new ObjectOutputStream(fileOutputStream).writeObject(segmentData);
          }
          finally
          {
              if (fileOutputStream!=null)
                  fileOutputStream.close();
          }
      }
  
      /**
       * Deserialises the contents of a JpegSegmentData from a file.
       * @param file the file to read from
       * @return the JpegSegmentData as read
       * @throws IOException if problems occur while reading
       * @throws ClassNotFoundException if problems occur while deserialising
       */
      @NotNull
      public static JpegSegmentData fromFile(@NotNull File file) throws IOException, ClassNotFoundException
      {
          ObjectInputStream inputStream = null;
          try
          {
              inputStream = new ObjectInputStream(new FileInputStream(file));
              return (JpegSegmentData)inputStream.readObject();
          }
          finally
          {
              if (inputStream!=null)
                  inputStream.close();
          }
      }
  }
  