minstrel/internal/db/queries/browse.sql

-- Every query in this file filters `tracks.missing_since IS NULL`. A row whose
-- file has vanished keeps its genre forever — the scanner walks the
-- filesystem, so it never revisits a path that no longer exists — and
-- browsing is a way of finding something to play, so a track that cannot play
-- should not shape it.
--
-- The year axis filters too, so the two axes agree: an album whose every file
-- has vanished is absent from both, rather than absent from its genre and
-- still listed under its year, where opening it would find nothing playable.
--
-- Hiding rather than showing-and-marking, because browsing is how you go
-- looking for something to play; the admin missing-files surface is where
-- absence is reported.
--
-- The predicate is "has at least one playable track", so it also excludes an
-- album with no tracks at all. That is the same answer for the same reason:
-- nothing to play, nothing to browse to.

-- name: ListGenresWithCount :many
-- Genre browse index.
--
-- Genres live inline on tracks.genre as a delimited string, so this splits on
-- the same [;,] pattern already used by recommendation.sql and discover.sql —
-- a track tagged "Rock;Pop" must count toward both, and diverging from the
-- established pattern here would make the browse surface disagree with what
-- the recommendation engine believes the library contains.
--
-- trim() but deliberately NO lower(): trimming repairs an artifact of OUR
-- splitting ("Rock; Pop" yields " Pop", and showing that as a distinct genre
-- would be a bug), whereas case is what the tag actually says. Raw ID3 is
-- exposed as-is, so "Rock" and "rock" appear as separate rows.
--
-- COUNT(DISTINCT) because a sloppy tag like "Rock;Rock" would otherwise
-- inflate its own row.
--
-- Ordered by count first: raw ID3 data has a long tail of one-off junk tags,
-- so alphabetical would bury the handful of genres a library actually has
-- a lot of. Name breaks ties for a stable order.
SELECT trim(g.genre) AS genre, COUNT(DISTINCT tracks.id)::bigint AS track_count
FROM tracks
JOIN LATERAL regexp_split_to_table(coalesce(tracks.genre, ''), '[;,]') AS g(genre) ON true
WHERE trim(g.genre) <> ''
  AND tracks.missing_since IS NULL
GROUP BY trim(g.genre)
-- Ordered by the expression, not the output alias: `ORDER BY genre` is
-- ambiguous between the alias and tracks.genre, and sqlc rejects it.
ORDER BY track_count DESC, trim(g.genre);

-- name: ListAlbumsByGenreWithArtist :many
-- Albums for one genre, joined with artist_name for the browse grid.
-- An album belongs to a genre when ANY of its tracks carry it. Splits and
-- trims identically to ListGenresWithCount — if the list is built by
-- splitting and the detail matched exactly, every multi-genre track would
-- produce a genre row that leads to an empty page.
SELECT sqlc.embed(albums), artists.name AS artist_name
FROM albums
JOIN artists ON artists.id = albums.artist_id
WHERE EXISTS (
    SELECT 1
    FROM tracks
    JOIN LATERAL regexp_split_to_table(coalesce(tracks.genre, ''), '[;,]') AS g(genre) ON true
    WHERE tracks.album_id = albums.id
      AND tracks.missing_since IS NULL
      AND trim(g.genre) = trim(sqlc.arg(genre)::text)
)
ORDER BY albums.sort_title, albums.id
LIMIT sqlc.arg(lim) OFFSET sqlc.arg(off);

-- name: CountAlbumsByGenre :one
-- Total for the paging envelope. EXISTS mirrors the list query exactly; a
-- JOIN + DISTINCT here would count differently the moment an album has two
-- tracks carrying the same genre.
SELECT COUNT(*) FROM albums
WHERE EXISTS (
    SELECT 1
    FROM tracks
    JOIN LATERAL regexp_split_to_table(coalesce(tracks.genre, ''), '[;,]') AS g(genre) ON true
    WHERE tracks.album_id = albums.id
      AND tracks.missing_since IS NULL
      AND trim(g.genre) = trim(sqlc.arg(genre)::text)
);

-- name: ListAlbumYearsWithCount :many
-- Year browse index. Only albums with a release_date appear — an
-- album with no date isn't "year unknown" as a browsable bucket, it's absent
-- from this axis, and the UI says so rather than inventing a 0 row.
-- Newest first: recent releases are the likelier browse target.
SELECT EXTRACT(YEAR FROM release_date)::int AS year, COUNT(*)::bigint AS album_count
FROM albums
WHERE release_date IS NOT NULL
  AND EXISTS (
    SELECT 1 FROM tracks
     WHERE tracks.album_id = albums.id
       AND tracks.missing_since IS NULL
  )
GROUP BY year
ORDER BY year DESC;

-- name: ListAlbumsByYearRangeWithArtist :many
-- Albums released within an inclusive year range, for the albums-page filter.
SELECT sqlc.embed(albums), artists.name AS artist_name
FROM albums
JOIN artists ON artists.id = albums.artist_id
WHERE albums.release_date IS NOT NULL
  AND EXTRACT(YEAR FROM albums.release_date)::int
      BETWEEN sqlc.arg(year_from)::int AND sqlc.arg(year_to)::int
  AND EXISTS (
    SELECT 1 FROM tracks
     WHERE tracks.album_id = albums.id
       AND tracks.missing_since IS NULL
  )
ORDER BY albums.sort_title, albums.id
LIMIT sqlc.arg(lim) OFFSET sqlc.arg(off);

-- name: CountAlbumsByYearRange :one
SELECT COUNT(*) FROM albums
WHERE release_date IS NOT NULL
  AND EXTRACT(YEAR FROM release_date)::int
      BETWEEN sqlc.arg(year_from)::int AND sqlc.arg(year_to)::int
  AND EXISTS (
    SELECT 1 FROM tracks
     WHERE tracks.album_id = albums.id
       AND tracks.missing_since IS NULL
  );

-- name: ListGenresForAlbum :many
-- Distinct genres carried by an album's tracks, for the album detail page's
-- quick-jump chips. Split and trimmed identically to ListGenresWithCount, so a
-- chip always leads to a page that actually contains this album.
SELECT DISTINCT trim(g.genre) AS genre
FROM tracks
JOIN LATERAL regexp_split_to_table(coalesce(tracks.genre, ''), '[;,]') AS g(genre) ON true
WHERE tracks.album_id = $1 AND trim(g.genre) <> ''
  AND tracks.missing_since IS NULL
ORDER BY trim(g.genre);

-- name: ListGenresForArtist :many
-- Same, across everything by one artist. Alphabetical rather than by count:
-- an artist's genre set is small, and a stable order reads better than a
-- frequency ranking nobody asked about.
SELECT DISTINCT trim(g.genre) AS genre
FROM tracks
JOIN LATERAL regexp_split_to_table(coalesce(tracks.genre, ''), '[;,]') AS g(genre) ON true
WHERE tracks.artist_id = $1 AND trim(g.genre) <> ''
  AND tracks.missing_since IS NULL
ORDER BY trim(g.genre);