Mp4GenreField.java

package org.jaudiotagger.tag.mp4.field;

import org.jaudiotagger.audio.mp4.atom.Mp4BoxHeader;
import org.jaudiotagger.logging.ErrorMessage;
import org.jaudiotagger.tag.mp4.Mp4FieldKey;
import org.jaudiotagger.tag.mp4.atom.Mp4DataBox;
import org.jaudiotagger.tag.reference.GenreTypes;

import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.ArrayList;

/**
 * Represents the Genre field , when user has selected from the set list of genres
 * <p/>
 * <p>This class allows you to retrieve either the internal genreid, or the display value
 */
public class Mp4GenreField extends Mp4TagTextNumberField {
    public Mp4GenreField(String id, ByteBuffer data) throws UnsupportedEncodingException {
        super(id, data);
    }

    /**
     * Precheck to see if the value is a valid genre or whether you should use a custom genre.
     *
     * @param genreId
     * @return
     */
    public static boolean isValidGenre(String genreId) {
        //Is it an id (within old id3 range)      
        try {
            short genreVal = Short.parseShort(genreId);
            if ((genreVal - 1) <= GenreTypes.getMaxStandardGenreId()) {
                return true;
            }
        } catch (NumberFormatException nfe) {
            //Do Nothing test as String instead
        }

        //Is it the String value ?
        Integer id3GenreId = GenreTypes.getInstanceOf().getIdForValue(genreId);
        if (id3GenreId != null) {
            if (id3GenreId <= GenreTypes.getMaxStandardGenreId()) {
                return true;
            }
        }
        return false;
    }

    /**
     * Construct genre, if cant find match just default to first genre
     *
     * @param genreId key into ID3v1 list (offset by one) or String value in ID3list
     */
    public Mp4GenreField(String genreId) {
        super(Mp4FieldKey.GENRE.getFieldName(), genreId);

        //Is it an id
        try {
            short genreVal = Short.parseShort(genreId);
            if ((genreVal - 1) <= GenreTypes.getMaxStandardGenreId()) {
                numbers = new ArrayList<Short>();
                numbers.add(genreVal);
                return;
            }
            //Default
            numbers = new ArrayList<Short>();
            numbers.add((short) (1));
            return;
        } catch (NumberFormatException nfe) {
            //Do Nothing test as String instead
        }

        //Is it the String value ?
        Integer id3GenreId = GenreTypes.getInstanceOf().getIdForValue(genreId);
        if (id3GenreId != null) {
            if (id3GenreId <= GenreTypes.getMaxStandardGenreId()) {
                numbers = new ArrayList<Short>();
                numbers.add((short) (id3GenreId + 1));
                return;
            }
        }
        numbers = new ArrayList<Short>();
        numbers.add((short) (1));
    }

    protected void build(ByteBuffer data) throws UnsupportedEncodingException {
        //Data actually contains a 'Data' Box so process data using this
        Mp4BoxHeader header = new Mp4BoxHeader(data);
        Mp4DataBox databox = new Mp4DataBox(header, data);
        dataSize = header.getDataLength();
        numbers = databox.getNumbers();

        int genreId = numbers.get(0);
        //Get value, we have to adjust index by one because iTunes labels from one instead of zero
        content = GenreTypes.getInstanceOf().getValueForId(genreId - 1);

        //Some apps set genre to invalid value, we dont disguise this by setting content to empty string we leave
        //as null so apps can handle if they wish, but we do display a warning to make them aware.
        if (content == null) {
            //logger.warning(ErrorMessage.MP4_GENRE_OUT_OF_RANGE.getMsg(genreId));
        }
    }
}