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minstrel/internal/db/queries/system_playlists.sql
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SQL

-- M7 #352 slice 2: system-generated playlist queries.
-- name: ListActiveUsersForSystemPlaylists :many
-- Active = had a play in the last 7 days. The cron iterates this list.
SELECT u.id FROM users u
WHERE EXISTS (
SELECT 1 FROM play_events pe
WHERE pe.user_id = u.id
AND pe.started_at > now() - INTERVAL '7 days'
);
-- name: GetSystemPlaylistRun :one
SELECT user_id, last_run_at, last_run_date, in_flight, last_error
FROM system_playlist_runs
WHERE user_id = $1;
-- name: TryClaimSystemPlaylistRun :one
-- Atomic test-and-set on in_flight. Returns the row if we won the claim,
-- or pgx.ErrNoRows if someone else is already building.
INSERT INTO system_playlist_runs (user_id, in_flight)
VALUES ($1, true)
ON CONFLICT (user_id) DO UPDATE
SET in_flight = true
WHERE system_playlist_runs.in_flight = false
RETURNING user_id, last_run_at, last_run_date, in_flight, last_error;
-- name: FinishSystemPlaylistRun :exec
-- Mark a successful build complete.
UPDATE system_playlist_runs
SET last_run_at = $2,
last_run_date = $3,
in_flight = false,
last_error = NULL
WHERE user_id = $1;
-- name: FailSystemPlaylistRun :exec
-- Mark a failed build complete (in_flight=false, error captured).
UPDATE system_playlist_runs
SET in_flight = false,
last_error = $2
WHERE user_id = $1;
-- name: ClearStaleSystemPlaylistInFlight :exec
-- Cron startup recovery: clear any in_flight=true rows from a previously
-- crashed process. Safe because at startup, by definition, nothing is
-- still building.
UPDATE system_playlist_runs SET in_flight = false WHERE in_flight = true;
-- name: PickSeedArtists :many
-- Top-3 most-engaged distinct artists in the user's last 7 days.
-- Score = unskipped-play count + 5 if user has liked the artist.
WITH plays AS (
SELECT t.artist_id,
COUNT(*) FILTER (WHERE pe.was_skipped = false) AS play_count
FROM play_events pe
JOIN tracks t ON t.id = pe.track_id
WHERE pe.user_id = $1
AND pe.started_at > now() - INTERVAL '7 days'
AND t.artist_id IS NOT NULL
GROUP BY t.artist_id
),
liked AS (
SELECT artist_id FROM general_likes_artists WHERE user_id = $1
)
SELECT p.artist_id,
(p.play_count + CASE WHEN l.artist_id IS NOT NULL THEN 5 ELSE 0 END)::bigint AS score
FROM plays p
LEFT JOIN liked l ON l.artist_id = p.artist_id
ORDER BY score DESC, p.artist_id
LIMIT 3;
-- name: PickTopPlayedTrackForUser :one
-- For-You seed selection. Returns the user's most-played non-skipped
-- track in the last 7 days; tie-break by track_id for determinism.
SELECT t.id
FROM play_events pe
JOIN tracks t ON t.id = pe.track_id
WHERE pe.user_id = $1
AND pe.started_at > now() - INTERVAL '7 days'
AND pe.was_skipped = false
GROUP BY t.id
ORDER BY COUNT(*) DESC, t.id
LIMIT 1;
-- name: PickTopPlayedTrackForArtistByUser :one
-- "Songs like X" seed selection. Returns the user's most-played non-skipped
-- track by artist X in the last 7 days. Falls back to the artist's most-
-- recent album's first track if no plays exist.
-- Cast to uuid so sqlc infers pgtype.UUID rather than interface{}.
SELECT COALESCE(
(SELECT t.id
FROM play_events pe
JOIN tracks t ON t.id = pe.track_id
WHERE pe.user_id = $1
AND t.artist_id = $2
AND pe.started_at > now() - INTERVAL '7 days'
AND pe.was_skipped = false
GROUP BY t.id
ORDER BY COUNT(*) DESC, t.id
LIMIT 1),
(SELECT t.id
FROM tracks t
JOIN albums a ON a.id = t.album_id
WHERE t.artist_id = $2
ORDER BY a.release_date DESC NULLS LAST,
t.disc_number NULLS LAST,
t.track_number NULLS LAST,
t.id
LIMIT 1)
)::uuid AS id;
-- name: PickTopAlbumCoverForArtistByUser :one
-- "Songs like X" cover. Most-played album by user; tie-break by most-recent
-- release. NULL if the artist has no albums or all covers are NULL.
-- Note: albums uses cover_art_path (not cover_path).
SELECT a.cover_art_path
FROM albums a
LEFT JOIN tracks t ON t.album_id = a.id
LEFT JOIN play_events pe
ON pe.track_id = t.id
AND pe.user_id = $1
AND pe.was_skipped = false
WHERE a.artist_id = $2
AND a.cover_art_path IS NOT NULL
GROUP BY a.id, a.release_date, a.cover_art_path
ORDER BY COUNT(pe.id) DESC, a.release_date DESC NULLS LAST, a.id
LIMIT 1;
-- name: DeleteSystemPlaylistsForUser :exec
-- Atomic-replace step. CASCADE on playlist_tracks.playlist_id handles
-- the join rows.
DELETE FROM playlists WHERE user_id = $1 AND kind = 'system';
-- name: ListPlaylistsByUserAndKind :many
-- Powers GET /api/me/playlists?kind=. Sorted by updated_at DESC.
SELECT id, user_id, name, description, is_public, kind, system_variant,
seed_artist_id, cover_path, track_count, duration_sec,
created_at, updated_at
FROM playlists
WHERE user_id = $1
AND ($2::text = 'all' OR kind = $2)
ORDER BY updated_at DESC;