import { unstable_cache } from "next/cache";
import { prisma } from "@/lib/prisma";

/**
 * Returns the set of user IDs that the given staff member has marked as
 * "watch". Cached 60s + tag-invalidated by toggleUserWatch.
 */
export async function getWatchedUserIds(staffId: number): Promise<Set<number>> {
	const ids = await getCachedWatchedIds(staffId);
	return new Set(ids);
}

const getCachedWatchedIds = unstable_cache(
	async (staffId: number): Promise<number[]> => {
		const rows = await prisma.userWatch.findMany({
			where: { staffId },
			select: { targetUserId: true },
		});
		return rows.map((r) => r.targetUserId);
	},
	["user-watch-list"],
	{ revalidate: 60, tags: ["user-watch"] },
);