/*
 * Entagged Audio Tag library
 
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *  
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package entagged.audioformats.mp3.util;

import entagged.audioformats.exceptions.*;
import entagged.audioformats.mp3.*;

import java.io.*;

public class Id3v1TagReader {

	public Id3v1Tag read( RandomAccessFile raf ) throws CannotReadException, IOException {
		Id3v1Tag tag = new Id3v1Tag();
		//Check wether the file contains an Id3v1 tag--------------------------------
		raf.seek( raf.length() - 128 );
		
		byte[] b = new byte[3];
		raf.read( b );
		raf.seek(0);
		String tagS = new String( b );
		if(!tagS.equals( "TAG" )){
			throw new CannotReadException("There is no Id3v1 Tag in this file");
		}
		
		raf.seek( raf.length() - 128 + 3 );
		//Parse the tag -)------------------------------------------------
		String songName = read(raf, 30);
		//------------------------------------------------
		String artist = read(raf, 30);
		//------------------------------------------------
		String album = read(raf, 30);
		//------------------------------------------------
		String year = read(raf, 4);
		//------------------------------------------------
		String comment = read(raf, 30);
		//------------------------------------------------
		String trackNumber = "";
		
		raf.seek(raf.getFilePointer() - 2);
		b = new byte[2];
		raf.read(b);
		
		if ( b[0] == 0 ) {
			Integer track = new Integer( b[1] );
			trackNumber = track.toString();
		}
		//------------------------------------------------
		byte genreByte = raf.readByte();
		raf.seek(0);

		tag.setTitle(songName);
		tag.setArtist(artist);
		tag.setAlbum(album);
		tag.setYear(year);
		tag.setComment(comment);
		tag.setTrack(trackNumber);
		tag.setGenre(tag.translateGenre(genreByte));

	
		return tag;
	}
	
	private String read(RandomAccessFile raf, int length) throws IOException {
		byte[] b = new byte[length];
		raf.read( b );
		String ret = new String( b ).trim();
		int i = ret.indexOf("\u0000");
		if(i != -1)
		    return ret.substring(0, i+1);
		
	    return ret;
	}
}