Add basic method to find duplicates

from collections.abc import Mapping, Sequence

from collections import defaultdict

from tqdm import tqdm

from karaokatalog.Library import Library

from karaokatalog.Song import Song, Title, Artist

type TitleAndArtist = tuple[Title, Artist]

def find_duplicates(l: Library) -> Mapping[TitleAndArtist, Sequence[Song]]:

    """

    Find all song duplicates, i.e., all songs with the same title and same artist.

    Note that those might not be identical for several reasons:

    - Maybe the associated track is different (e.g. one is a music video, the other just the song)

    - Maybe the lyrics or notes are different (e.g. one is created with more attention to detail)

    - Maybe an artist just happens to share a name with another artist, who both published a song with the same title

    - ...

    """

    songs_by_title_and_artist: defaultdict[TitleAndArtist, list[Song]] = defaultdict(

        list

    )

    for song in tqdm(l.songs, unit=" songs"):

        songs_by_title_and_artist[(song.title, song.artist)].append(song)

    return {

        normalized_title_and_artist: songs

        for normalized_title_and_artist, songs in songs_by_title_and_artist.items()

        if len(songs) > 1

    }