#!/usr/bin/python2

import eyed3

import sys

def err(*args):
    sys.stderr.write(" ".join(args) + "\n")

def die(*args):
    err(*args)
    sys.exit(1)

USAGE='Usage: {0} [file]'.format(sys.argv[0])

def to_file_case(name):
    for ch in name:
        if ord(ch) > 127:
            err("ERROR: {0} outside ASCII range".format(ord(ch)))
            raise Exception("NonAsciiName")
    return '_'.join(name.lower().split())

filenames = sys.argv[1:]

if not filenames:
    die(USAGE)

def do_rename(filename):
    audiofile = eyed3.load(filename)

    (tn,_) = audiofile.tag.track_num
    if tn is None:
        err("ERROR: Unknown track number for file `{0}'".format(filename))

    title = audiofile.tag.title
    newname = '{0:02}_-_{1}'.format(tn, to_file_case(title))

    print "renaming: `{0}' -> `{1}'".format(filename, newname)
    audiofile.rename(newname)

for f in filenames:
    try:
        do_rename(f)
    except:
        err("ERROR: Unable to rename `{0}'".format(f))