def time_format(seconds):
    """
    Convert seconds into DATE HOUR MIN SEC format.
    """
    if seconds is not None:
        seconds = int(seconds)
        d = seconds // (3600 * 24)
        h = seconds // 3600 % 24
        m = seconds % 3600 // 60
        s = seconds % 3600 % 60
        if d > 0:
            return '{:02d}D {:02d}H {:02d}m {:02d}s'.format(d, h, m, s)
        elif h > 0:
            return '{:02d}H {:02d}m {:02d}s'.format(h, m, s)
        elif m > 0:
            return '{:02d}m {:02d}s'.format(m, s)
        elif s > 0:
            return '{:02d}s'.format(s)
    return '-'