Add basic method to find duplicates

karaokatalog/find_duplicates.py

@@ -0,0 +1,34 @@
+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
+    }