package org.jaudiotagger.audio.asf.io;

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

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

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

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

 import java.io.IOException;

 import java.io.InputStream;

 import java.math.BigInteger;

 /**

  * Reads and interprets the &quot;Language List Object&quot; of ASF files.<br>

  * 

  * @author Christian Laireiter

  */

 public class LanguageListReader implements ChunkReader {

     /**

      * The GUID this reader {@linkplain #getApplyingIds() applies to}

      */

     private final static GUID[] APPLYING = { GUID.GUID_LANGUAGE_LIST };

     /**

      * {@inheritDoc}

      */

     public boolean canFail() {

         return false;

     }

     /**

      * {@inheritDoc}

      */

     public GUID[] getApplyingIds() {

         return APPLYING.clone();

     }

     /**

      * {@inheritDoc}

      */

     public Chunk read(final GUID guid, final InputStream stream,

             final long streamPosition) throws IOException {

         assert GUID.GUID_LANGUAGE_LIST.equals(guid);

         final BigInteger chunkLen = Utils.readBig64(stream);

         final int readUINT16 = Utils.readUINT16(stream);

         final LanguageList result = new LanguageList(streamPosition, chunkLen);

         for (int i = 0; i < readUINT16; i++) {

             final int langIdLen = (stream.read() & 0xFF);

             final String langId = Utils

                     .readFixedSizeUTF16Str(stream, langIdLen);

             // langIdLen = 2 bytes for each char and optionally one zero

             // termination character

             assert langId.length() == langIdLen / 2 - 1

                     || langId.length() == langIdLen / 2;

             result.addLanguage(langId);

         }

         return result;

     }

 }