Multiple meeting lobbies and beta-gated features (3.5.2)

- /meeting add-lobby, remove-lobby, lobbies: up to 10 lobbies per server, capped in the database
- Deleted voice channels are dropped from the lobbies
- Beta features: registered only in the beta server and usable only with the Beta Tester role (BETA_GUILD_ID, BETA_ROLE_ID); fails closed
- /beta (bot owner only) shows how beta access is set up

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

internal/db/repos/settingsrepo/repo.go

@@ -3,6 +3,9 @@ package settingsrepo
 import (
 	"context"
 	"database/sql"
+	"errors"
+
+	"github.com/jackc/pgx/v5/pgconn"
 )
 
 type Repo struct {
@@ -25,36 +28,75 @@ func NewRepo(db *sql.DB) *Repo {
 	return &Repo{db: db}
 }
 
-func (r *Repo) SetMeetingLobbyChannel(ctx context.Context, guildID int64, lobbyChannelID int64) error {
+// MaxMeetingLobbies is how many lobby channels one server can have. The
+// database enforces it too (a trigger from the API's migration 000020), so
+// the command and the dashboard can't disagree.
+const MaxMeetingLobbies = 10
+
+// ErrMeetingLobbyLimit means the server already has MaxMeetingLobbies.
+var ErrMeetingLobbyLimit = errors.New("meeting lobby limit reached")
+
+// pgLimitExceeded is the error code the database raises for one lobby too many.
+const pgLimitExceeded = "54000"
+
+// AddMeetingLobby makes channelID a lobby. added is false when it already
+// was one; going over the limit is ErrMeetingLobbyLimit.
+func (r *Repo) AddMeetingLobby(ctx context.Context, guildID, channelID int64) (added bool, err error) {
 	const q = `
-		INSERT INTO meeting_settings (guild_id, lobby_channel_id)
+		INSERT INTO meeting_lobbies (guild_id, channel_id)
 		VALUES ($1, $2)
-		ON CONFLICT (guild_id)
-		DO UPDATE SET lobby_channel_id = EXCLUDED.lobby_channel_id
+		ON CONFLICT DO NOTHING
 	`
-	_, err := r.db.ExecContext(ctx, q, guildID, lobbyChannelID)
-	return err
+	res, err := r.db.ExecContext(ctx, q, guildID, channelID)
+	var pgErr *pgconn.PgError
+	if errors.As(err, &pgErr) && pgErr.Code == pgLimitExceeded {
+		return false, ErrMeetingLobbyLimit
+	}
+	if err != nil {
+		return false, err
+	}
+	n, err := res.RowsAffected()
+	return n > 0, err
 }
 
-func (r *Repo) GetMeetingLobbyChannel(ctx context.Context, guildID int64) (channelID int64, ok bool, err error) {
-	const q = `
-		SELECT lobby_channel_id
-		FROM meeting_settings
-		WHERE guild_id = $1
-	`
-	row := r.db.QueryRowContext(ctx, q, guildID)
-	var ch sql.NullInt64
-	switch err := row.Scan(&ch); err {
-	case nil:
-		if !ch.Valid {
-			return 0, false, nil
-		}
-		return ch.Int64, true, nil
-	case sql.ErrNoRows:
-		return 0, false, nil
-	default:
-		return 0, false, err
+// RemoveMeetingLobby takes a channel off the lobby list; removed is false
+// when it wasn't one.
+func (r *Repo) RemoveMeetingLobby(ctx context.Context, guildID, channelID int64) (removed bool, err error) {
+	const q = `DELETE FROM meeting_lobbies WHERE guild_id = $1 AND channel_id = $2`
+	res, err := r.db.ExecContext(ctx, q, guildID, channelID)
+	if err != nil {
+		return false, err
 	}
+	n, err := res.RowsAffected()
+	return n > 0, err
+}
+
+// ListMeetingLobbies returns a server's lobbies, oldest first.
+func (r *Repo) ListMeetingLobbies(ctx context.Context, guildID int64) ([]int64, error) {
+	const q = `SELECT channel_id FROM meeting_lobbies WHERE guild_id = $1 ORDER BY created_at, channel_id`
+	rows, err := r.db.QueryContext(ctx, q, guildID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var out []int64
+	for rows.Next() {
+		var id int64
+		if err := rows.Scan(&id); err != nil {
+			return nil, err
+		}
+		out = append(out, id)
+	}
+	return out, rows.Err()
+}
+
+// IsMeetingLobby reports whether channelID is one of the server's lobbies.
+// It runs whenever someone joins a voice channel, so it's one indexed lookup.
+func (r *Repo) IsMeetingLobby(ctx context.Context, guildID, channelID int64) (bool, error) {
+	const q = `SELECT EXISTS (SELECT 1 FROM meeting_lobbies WHERE guild_id = $1 AND channel_id = $2)`
+	var ok bool
+	err := r.db.QueryRowContext(ctx, q, guildID, channelID).Scan(&ok)
+	return ok, err
 }
 
 func (r *Repo) AddMeetingTempChannel(ctx context.Context, guildID, channelID, createdBy int64) error {