package org.farng.mp3.id3;

import java.io.IOException;
import java.io.RandomAccessFile;

import org.farng.mp3.InvalidTagException;
import org.farng.mp3.object.ObjectNumberHashMap;
import org.farng.mp3.object.ObjectNumberVariableLength;

/**
 * <h3>4.21.   Position synchronisation frame</h3>
 * <p/>
 * <p>   This frame delivers information to the listener of how far into the<br>    audio stream he
 * picked up; in effect, it states the time offset from<br>    the first frame in the stream. The frame layout
 * is:</p>
 * <p/>
 * <p>     <Head for 'Position synchronisation', ID: "POSS"><br>
 * <p/>
 *      Time stamp format         $xx<br>
 *      Position                 
 * $xx (xx ...)</p>
 * <p/>
 * <p>   Where time stamp format is:</p>
 * <p/>
 * <p>     $01  Absolute time, 32 bit sized, using MPEG frames as unit<br>
 *      $02  Absolute time, 32 bit sized, using milliseconds as unit</p>
 * <p/>
 * <p>   and position is where in the audio the listener starts to receive,<br>    i.e. the
 * beginning of the next frame. If this frame is used in the<br>
 * <p/>
 *    beginning of a file the value is always 0. There may only be one<br>    "POSS" frame
 * in each tag.<br> </p>
 *
 * @author Eric Farng
 * @version $Revision: 2374 $
 */
public class FrameBodyPOSS extends AbstractID3v2FrameBody {

    /**
     * Creates a new FrameBodyPOSS object.
     */
    public FrameBodyPOSS() {
        super();
    }

    /**
     * Creates a new FrameBodyPOSS object.
     */
    public FrameBodyPOSS(final FrameBodyPOSS body) {
        super(body);
    }

    /**
     * Creates a new FrameBodyPOSS object.
     */
    public FrameBodyPOSS(final byte timeStampFormat, final long position) {
        setObject(ObjectNumberHashMap.TIME_STAMP_FORMAT, new Byte(timeStampFormat));
        setObject("Position", new Long(position));
    }

    /**
     * Creates a new FrameBodyPOSS object.
     */
    public FrameBodyPOSS(final RandomAccessFile file) throws IOException, InvalidTagException {
        this.read(file);
    }

    public String getIdentifier() {
        return "POSS";
    }

    protected void setupObjectList() {
        appendToObjectList(new ObjectNumberHashMap(ObjectNumberHashMap.TIME_STAMP_FORMAT, 1));
        appendToObjectList(new ObjectNumberVariableLength("Position", 1));
    }
}