minstrel/internal/db/migrations/0086_library_album_matches.up.sql

-- Every library album is matched to MusicBrainz before it goes on the list, so
-- its metadata comes from MusicBrainz. The listing in 0085 took only albums
-- whose tags already named their release group and artist; the rest are now
-- matched by the release their tags name, the artist's discography, or a
-- search, and checked against their own tracks.
--
--   library_album_matches  one row per album the listing has decided:
--                          listed (with how it was matched) or unmatched
--                          (with why). It is the record that the listing
--                          saw the album, so an album taken off the list
--                          is never listed again.
CREATE TABLE library_album_matches (
    album_id           uuid PRIMARY KEY REFERENCES albums (id) ON DELETE CASCADE,
    outcome            text NOT NULL
        CONSTRAINT library_album_matches_outcome_check CHECK (outcome IN ('listed', 'unmatched')),
    --   tags         its tags named the release group.
    --   release      its tags named a release; MusicBrainz named the group.
    --   discography  its title is one of the artist's release groups.
    --   search       MusicBrainz's search found it by artist and title.
    method             text NOT NULL DEFAULT ''
        CONSTRAINT library_album_matches_method_check CHECK (method IN ('', 'tags', 'release', 'discography', 'search')),
    release_group_mbid text NOT NULL DEFAULT '',
    detail             text NOT NULL DEFAULT '',
    decided_at         timestamptz NOT NULL DEFAULT now()
);

CREATE INDEX library_album_matches_unmatched_idx ON library_album_matches (decided_at) WHERE outcome = 'unmatched';

-- The albums 0085's listing already took, by its own test, are decided:
-- one taken off the list since stays off.
INSERT INTO library_album_matches (album_id, outcome, method, release_group_mbid)
SELECT a.id, 'listed', 'tags', a.release_group_mbid
  FROM albums a
  JOIN artists ar ON ar.id = a.artist_id
  JOIN acquisition_settings s ON s.id = true
 WHERE s.library_listing_started_at IS NOT NULL
   AND a.created_at <= s.library_listing_started_at
   AND a.release_group_mbid IS NOT NULL AND a.release_group_mbid <> ''
   AND ar.mbid IS NOT NULL AND ar.mbid <> ''
   AND EXISTS (SELECT 1 FROM tracks t WHERE t.album_id = a.id);

-- The rest are matched by the wanted worker after boot: the listing resumes.
UPDATE acquisition_settings
   SET library_listed_at = NULL, library_unlisted = 0
 WHERE library_listing_started_at IS NOT NULL;