Tags MP3 files to their appropriate ID3 tag based on their path and filename.

tag.py

# -*- coding: utf-8 -*-
import argparse, glob, os

try:
    from mutagen.easyid3 import EasyID3
except ImportError:
    print('"mutagen" package is required for this to work.')
    print('Please install it using pip or any other package manager')
    exit(0)


def update_file(path, **kwargs):
    audio = EasyID3(path)

    filename = os.path.basename(path)
    names = [x.strip() for x in filename.replace('.mp3', '').split('-')]
    folders = path.split('/')
    folders.pop()  # We remove the filename

    for key in ('title', 'artist', 'album', 'composer'):
        if kwargs.get(key):
            if kwargs.get(key).startswith('%'):
                try:
                    index = int(kwargs.get(key)[1:])
                    if index < 0:
                        audio[key] = folders[index]
                    else:
                        audio[key] = names[index]
                    continue
                except (ValueError, IndexError):
                    print('value error')
                    continue

            audio[key] = kwargs.get(key)
    audio.save()


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description="""Updates ID3 tags of one or multiple .mp3 files.
    You can pass arguments with variables in this format: %Xs where X is a number.
     - If X is more than 0, the filename will be split in parts with dash ("-") being the separator.
       In this case, the number X will match the part.
       For instance, given a filename "12 - Enjoy the silence - 2004.mp3", passing the argument
       "--title %1s" will set the title to "Enjoy the silence"
     - If X is less than 0, the value will match the path in reverse order.
       For instance, a given path of "/home/user/music/Linkin Park/Remixes 81-04/", passing the argument
       "--album %-1s" will set the album name to "Remixes 81-04"

    What's left to do:
        * Implement the year parameter
        * Allow for choosing what to split with (default is dash ("-") but we could set anything else)
        * Handle subsplit; For instance, an Album path could contain both year and name ("2004 - Remixes 81-04").
          Passing an argument such as "%-1;1s" could be something, but it becomes ugly...

    Accepted paramters:
        * -p, --path : The path to either a folder or an mp3 file (checked via the last 4 chars being equals to ".mp3")
        * --artist: Sets the artist's name
        * --album: Sets the album's name
        * --title: Sets the title's name
        * -- composer: Sets the composer's name

    (All the parameters except -p/--path are optional)
    """)
    parser.add_argument('-p', '--path', type=str, required=True)
    parser.add_argument('--artist', type=str, default=None, required=False)
    parser.add_argument('--album', type=str, default=None, required=False)
    parser.add_argument('--title', type=str, default=None, required=False)
    parser.add_argument('--composer', type=str, default=None, required=False)

    args = parser.parse_args()

    if args.path.endswith('.mp3'):
        # Process one file only
        if not os.path.exists(args.path):
            print('ERR: Given path was not found.')
            exit(1)
        update_file(args.path, artist=args.artist, album=args.album, title=args.title, composer=args.composer)
    else:
        full_path = os.path.abspath(args.path)
        if not os.path.isdir(full_path):
            print('ERR: Given path does not exists.')
            # exit(1)

        if args.title:
            try:
                assert args.title.startswith('%')
            except AssertionError:
                print('ERR: Title must be a variable based on the name')
                exit(1)

        files = glob.glob('{0}/**/*.mp3'.format(full_path), recursive=True)

        for fname in files:
            print(fname)
            update_file(fname, artist=args.artist, album=args.album, title=args.title, composer=args.composer)

    print('Done.')
    exit(0)