export interface EventTicketState {
	eventId: number;
	capacity: number | null;
	redemptionDeadline: Date | null;
	collectAddress: boolean;
	requireAddress: boolean;
	guestsUsed: number;
	spotsRemaining: number | null;
}

/**
 * Reads an event's voucher settings + live guest count within the caller's
 * connection/transaction. Absence of a settings row means uncapped/no
 * deadline/no address collection - the "absence over sentinels" convention
 * also used by the Feedback module.
 *
 * Pass forUpdate=true from inside the redeem transaction to lock the
 * settings row for the duration of that transaction, serializing concurrent
 * redemptions against the same event so the guestsUsed sum computed here
 * stays correct even under a last-spot race. Events with no settings row
 * (uncapped) don't need this - there's no cap to race against.
 */
export const getEventTicketState = async (conn: any, eventId: number, forUpdate = false): Promise<EventTicketState> => {
	const settingsQuery = `SELECT capacity, redemption_deadline, collect_address, require_address FROM event_ticket_settings WHERE event_id = ?${forUpdate ? ' FOR UPDATE' : ''}`;
	const settingsRows = await conn.query(settingsQuery, [eventId]);
	const capacity = settingsRows.length > 0 ? settingsRows[0].capacity : null;
	const redemptionDeadline = settingsRows.length > 0 ? settingsRows[0].redemption_deadline : null;
	const collectAddress = settingsRows.length > 0 ? !!settingsRows[0].collect_address : false;
	// Only meaningful when collectAddress is also true - the field isn't
	// shown/collected at all otherwise, so "required" is moot.
	const requireAddress = collectAddress && settingsRows.length > 0 ? !!settingsRows[0].require_address : false;

	const usedRows = await conn.query(
		"SELECT COALESCE(SUM(guest_count), 0) as used FROM redemptions WHERE event_id = ? AND status = 'ACTIVE'",
		[eventId]
	);
	const guestsUsed = Number(usedRows[0].used);
	const spotsRemaining = capacity === null ? null : Math.max(0, capacity - guestsUsed);

	return {eventId, capacity, redemptionDeadline, collectAddress, requireAddress, guestsUsed, spotsRemaining};
};