Store each client's play queue in the database

The queue lived in memory and was shared by all clients, so a restart or a
finished sync cleared it. Every client now has its own queue in the new
queue and queue_song tables (added to the undeployed migration 000006).

The music endpoints return the queue ID in the X-Queue-Id header and expect
it back. A request without an ID, or with an ended one, starts a new queue.
/music/reset ends the queue and returns a new ID, and a sync ends all
running queues. Ended queues are kept as history.

The deprecated legacy routes without the /api/v1 prefix are removed.

internal/db/repository/models.go

@@ -11,6 +11,23 @@ import (
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
+type Queue struct {
+	Uuid                uuid.UUID          `json:"uuid"`
+	CurrentSong         int32              `json:"current_song"`
+	LastFetchedSongUuid uuid.UUID          `json:"last_fetched_song_uuid"`
+	StartedAt           pgtype.Timestamptz `json:"started_at"`
+	EndedAt             pgtype.Timestamptz `json:"ended_at"`
+}
+
+type QueueSong struct {
+	QueueUuid      uuid.UUID          `json:"queue_uuid"`
+	SongNo         int32              `json:"song_no"`
+	SongUuid       uuid.UUID          `json:"song_uuid"`
+	SoundtrackName string             `json:"soundtrack_name"`
+	SongName       string             `json:"song_name"`
+	AddedAt        pgtype.Timestamptz `json:"added_at"`
+}
+
 type Session struct {
 	Token      string             `json:"token"`
 	IpAddress  string             `json:"ip_address"`

internal/db/repository/querier.go

@@ -13,6 +13,9 @@ import (
 
 type Querier interface {
 	AddHashToSong(ctx context.Context, arg AddHashToSongParams) error
+	// Appends the queue's last fetched song and makes it the current song.
+	// Does nothing when no song has been fetched since the last call.
+	AddLastFetchedToQueue(ctx context.Context, argUuid uuid.UUID) error
 	AddSong(ctx context.Context, arg AddSongParams) error
 	AddSongPlayed(ctx context.Context, arg AddSongPlayedParams) error
 	AddSongPlayedByUUID(ctx context.Context, argUuid uuid.UUID) error
@@ -23,9 +26,12 @@ type Querier interface {
 	ClearSongs(ctx context.Context) error
 	ClearSongsBySoundtrackId(ctx context.Context, soundtrackID int32) error
 	ClearSoundtracks(ctx context.Context) error
+	CreateQueue(ctx context.Context) (Queue, error)
 	CreateSession(ctx context.Context, arg CreateSessionParams) (Session, error)
 	DeleteExpiredSessions(ctx context.Context) error
 	DeleteSession(ctx context.Context, token string) error
+	EndActiveQueues(ctx context.Context) error
+	EndQueue(ctx context.Context, argUuid uuid.UUID) error
 	FetchAllSongs(ctx context.Context) ([]Song, error)
 	FindAllSoundtracks(ctx context.Context) ([]Soundtrack, error)
 	FindSongsFromSoundtrack(ctx context.Context, soundtrackID int32) ([]Song, error)
@@ -48,6 +54,7 @@ type Querier interface {
 	GetNeverPlayedSoundtracks(ctx context.Context) ([]GetNeverPlayedSoundtracksRow, error)
 	// Oldest played soundtracks (least recently played, but has been played at least once)
 	GetOldestPlayedSoundtracks(ctx context.Context, limit int32) ([]GetOldestPlayedSoundtracksRow, error)
+	GetQueue(ctx context.Context, argUuid uuid.UUID) (Queue, error)
 	GetRandomActiveSong(ctx context.Context) (GetRandomActiveSongRow, error)
 	GetSession(ctx context.Context, token string) (Session, error)
 	GetSongByUUID(ctx context.Context, argUuid uuid.UUID) (Song, error)
@@ -64,12 +71,16 @@ type Querier interface {
 	InsertSongInList(ctx context.Context, arg InsertSongInListParams) error
 	InsertSoundtrack(ctx context.Context, arg InsertSoundtrackParams) (InsertSoundtrackRow, error)
 	InsertSoundtrackWithExistingId(ctx context.Context, arg InsertSoundtrackWithExistingIdParams) error
+	// The song columns are NULL when the song has been removed from the library since.
+	ListQueueSongs(ctx context.Context, queueUuid uuid.UUID) ([]ListQueueSongsRow, error)
 	ListSessions(ctx context.Context) ([]Session, error)
 	MarkSoundtracksDeletedExcept(ctx context.Context, ids []int32) error
 	RemoveBrokenSong(ctx context.Context, arg RemoveBrokenSongParams) error
 	RemoveBrokenSongs(ctx context.Context, uuids []uuid.UUID) error
 	RemoveSoundtrackDeletionDate(ctx context.Context, id int32) error
 	ResetSoundtrackIdSeq(ctx context.Context) (int64, error)
+	SetQueueCurrentSong(ctx context.Context, arg SetQueueCurrentSongParams) error
+	SetQueueLastFetched(ctx context.Context, arg SetQueueLastFetchedParams) error
 	SetSoundtrackDeletionDate(ctx context.Context) error
 	SetSoundtrackFingerprint(ctx context.Context, arg SetSoundtrackFingerprintParams) error
 	UpdateSong(ctx context.Context, arg UpdateSongParams) error

internal/db/repository/queue.sql.go

@@ -0,0 +1,171 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.31.1
+// source: queue.sql
+
+package repository
+
+import (
+	"context"
+
+	"github.com/google/uuid"
+)
+
+const addLastFetchedToQueue = `-- name: AddLastFetchedToQueue :exec
+WITH added AS (
+    INSERT INTO queue_song (queue_uuid, song_no, song_uuid, soundtrack_name, song_name)
+    SELECT q.uuid,
+           (SELECT COALESCE(MAX(qs.song_no), -1) + 1 FROM queue_song qs WHERE qs.queue_uuid = q.uuid),
+           s.uuid, st.soundtrack_name, s.song_name
+    FROM queue q
+    JOIN song s ON s.uuid = q.last_fetched_song_uuid
+    JOIN soundtrack st ON st.id = s.soundtrack_id
+    WHERE q.uuid = $1
+    RETURNING queue_uuid, song_no
+)
+UPDATE queue SET current_song = added.song_no, last_fetched_song_uuid = NULL
+FROM added
+WHERE queue.uuid = added.queue_uuid
+`
+
+// Appends the queue's last fetched song and makes it the current song.
+// Does nothing when no song has been fetched since the last call.
+func (q *Queries) AddLastFetchedToQueue(ctx context.Context, argUuid uuid.UUID) error {
+	_, err := q.db.Exec(ctx, addLastFetchedToQueue, argUuid)
+	return err
+}
+
+const createQueue = `-- name: CreateQueue :one
+INSERT INTO queue DEFAULT VALUES
+RETURNING uuid, current_song, last_fetched_song_uuid, started_at, ended_at
+`
+
+func (q *Queries) CreateQueue(ctx context.Context) (Queue, error) {
+	row := q.db.QueryRow(ctx, createQueue)
+	var i Queue
+	err := row.Scan(
+		&i.Uuid,
+		&i.CurrentSong,
+		&i.LastFetchedSongUuid,
+		&i.StartedAt,
+		&i.EndedAt,
+	)
+	return i, err
+}
+
+const endActiveQueues = `-- name: EndActiveQueues :exec
+UPDATE queue SET ended_at = NOW()
+WHERE ended_at IS NULL
+`
+
+func (q *Queries) EndActiveQueues(ctx context.Context) error {
+	_, err := q.db.Exec(ctx, endActiveQueues)
+	return err
+}
+
+const endQueue = `-- name: EndQueue :exec
+UPDATE queue SET ended_at = NOW()
+WHERE uuid = $1 AND ended_at IS NULL
+`
+
+func (q *Queries) EndQueue(ctx context.Context, argUuid uuid.UUID) error {
+	_, err := q.db.Exec(ctx, endQueue, argUuid)
+	return err
+}
+
+const getQueue = `-- name: GetQueue :one
+SELECT uuid, current_song, last_fetched_song_uuid, started_at, ended_at
+FROM queue
+WHERE uuid = $1
+`
+
+func (q *Queries) GetQueue(ctx context.Context, argUuid uuid.UUID) (Queue, error) {
+	row := q.db.QueryRow(ctx, getQueue, argUuid)
+	var i Queue
+	err := row.Scan(
+		&i.Uuid,
+		&i.CurrentSong,
+		&i.LastFetchedSongUuid,
+		&i.StartedAt,
+		&i.EndedAt,
+	)
+	return i, err
+}
+
+const listQueueSongs = `-- name: ListQueueSongs :many
+SELECT qs.song_no, qs.song_uuid, qs.soundtrack_name, qs.song_name,
+       s.path, s.times_played, s.soundtrack_uuid
+FROM queue_song qs
+LEFT JOIN song s ON s.uuid = qs.song_uuid
+WHERE qs.queue_uuid = $1
+ORDER BY qs.song_no
+`
+
+type ListQueueSongsRow struct {
+	SongNo         int32     `json:"song_no"`
+	SongUuid       uuid.UUID `json:"song_uuid"`
+	SoundtrackName string    `json:"soundtrack_name"`
+	SongName       string    `json:"song_name"`
+	Path           *string   `json:"path"`
+	TimesPlayed    *int32    `json:"times_played"`
+	SoundtrackUuid uuid.UUID `json:"soundtrack_uuid"`
+}
+
+// The song columns are NULL when the song has been removed from the library since.
+func (q *Queries) ListQueueSongs(ctx context.Context, queueUuid uuid.UUID) ([]ListQueueSongsRow, error) {
+	rows, err := q.db.Query(ctx, listQueueSongs, queueUuid)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []ListQueueSongsRow
+	for rows.Next() {
+		var i ListQueueSongsRow
+		if err := rows.Scan(
+			&i.SongNo,
+			&i.SongUuid,
+			&i.SoundtrackName,
+			&i.SongName,
+			&i.Path,
+			&i.TimesPlayed,
+			&i.SoundtrackUuid,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const setQueueCurrentSong = `-- name: SetQueueCurrentSong :exec
+UPDATE queue SET current_song = $2
+WHERE uuid = $1
+`
+
+type SetQueueCurrentSongParams struct {
+	Uuid        uuid.UUID `json:"uuid"`
+	CurrentSong int32     `json:"current_song"`
+}
+
+func (q *Queries) SetQueueCurrentSong(ctx context.Context, arg SetQueueCurrentSongParams) error {
+	_, err := q.db.Exec(ctx, setQueueCurrentSong, arg.Uuid, arg.CurrentSong)
+	return err
+}
+
+const setQueueLastFetched = `-- name: SetQueueLastFetched :exec
+UPDATE queue SET last_fetched_song_uuid = $2
+WHERE uuid = $1
+`
+
+type SetQueueLastFetchedParams struct {
+	Uuid                uuid.UUID `json:"uuid"`
+	LastFetchedSongUuid uuid.UUID `json:"last_fetched_song_uuid"`
+}
+
+func (q *Queries) SetQueueLastFetched(ctx context.Context, arg SetQueueLastFetchedParams) error {
+	_, err := q.db.Exec(ctx, setQueueLastFetched, arg.Uuid, arg.LastFetchedSongUuid)
+	return err
+}