Track which account is interested in which events

Store a list of ids of events and slots that accounts have marked as
being interested in, and show aggeregate counts in the schedule.

server/generate-demo-schedule.ts

@@ -175,5 +175,40 @@ export function generateDemoAccounts(): Account[] {
 			type: (["regular", "crew", "admin"] as const)[Math.floor(random() ** 5 * 3)],
 		});
 	}
+
+	// These have a much higher probability of being in someone's interested list.
+	const desiredEvent = ["opening", "closing", "fursuit-games"];
+
+	for (const account of accounts) {
+		const interestedIds: string[] = [];
+		for (const id of desiredEvent) {
+			if (random() < 0.5) {
+				interestedIds.push(id);
+			}
+		}
+
+		const eventsToAdd = Math.floor(random() * 10);
+		while (interestedIds.length < eventsToAdd) {
+			const event = events[Math.floor(random() * events.length)];
+			const eventId = toId(event.name);
+			if (interestedIds.some(id => id.replace(/-\d+$/, "") === eventId)) {
+				continue;
+			}
+
+			if (event.slots.length === 1 || random() < 0.8) {
+				interestedIds.push(toId(event.name))
+			} else {
+				for (const index of event.slots.map((_, index) => index)) {
+					if (random() < 0.5) {
+						interestedIds.push(toId(`${toId(event.name)}-${index}`));
+					}
+				}
+			}
+		}
+
+		if (interestedIds.length) {
+			account.interestedIds = interestedIds;
+		}
+	}
 	return accounts;
 }