package org.jaudiotagger.audio.asf.io;

 import org.jaudiotagger.audio.asf.data.GUID;

 import org.jaudiotagger.audio.asf.util.Utils;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.OutputStream;

 import java.util.HashSet;

 import java.util.Set;

 /**

  * This {@link ChunkModifier} implementation is meant to remove selected chunks.<br>

  * 

  * @author Christian Laireiter

  */

 public class ChunkRemover implements ChunkModifier

 {

     /**

      * Stores the GUIDs, which are about to be removed by this modifier.<br>

      */

     private final Set<GUID> toRemove;

     /**

      * Creates an instance, for removing selected chunks.<br>

      * @param guids the GUIDs which are about to be removed by this modifier.

      */

     public ChunkRemover(GUID... guids)

     {

         this.toRemove = new HashSet<GUID>();

         for (GUID current : guids)

         {

             this.toRemove.add(current);

         }

     }

     /**

      * {@inheritDoc}

      */

     public boolean isApplicable(GUID guid)

     {

         return this.toRemove.contains(guid);

     }

     /**

      * {@inheritDoc}

      */

     public ModificationResult modify(GUID guid, InputStream source, OutputStream destination) throws IOException

     {

         ModificationResult result = null;

         if (guid != null)

         {

             assert isApplicable(guid);

             // skip the chunk length minus 24 bytes for the already read length and the guid.

             final long chunkLen = Utils.readUINT64(source);

             source.skip(chunkLen - 24);

             result = new ModificationResult(-1, -1 * chunkLen, guid);

         }

         else

         {

             // Now a chunk should be added, however, this implementation is for removal.

             result = new ModificationResult(0, 0);

         }

         return result;

     }

 }