feat: instance invites

server/utils/invites.ts

@@ -0,0 +1,52 @@
+import { and, eq, gt, lt, lte, or, sql } from 'drizzle-orm';
+import { invites, users } from '../../drizzle/schema';
+import { db } from '../lib/db';
+
+export const INVITE_TOKEN_HEADER = 'x-invite-token';
+export const INVITE_LIFETIME_MS = 7 * 24 * 60 * 60 * 1000;
+
+// still has uses left and has not run out
+const usable = () => and(lt(invites.uses, invites.maxUses), gt(invites.expiresAt, new Date()));
+
+/**
+ * Takes one use of an invite. It is a single statement, so two people
+ * registering with the same single use link at once cannot both get in.
+ */
+export const claimInvite = async (token: string): Promise<boolean> => {
+    const claimed = await db.update(invites)
+        .set({ uses: sql`${invites.uses} + 1` })
+        .where(and(eq(invites.token, token), usable()))
+        .returning({ id: invites.id });
+
+    return claimed.length > 0;
+};
+
+/** Gives a use back when the registration it was taken for did not go through. */
+export const releaseInvite = async (token: string) => {
+    await db.update(invites)
+        .set({ uses: sql`${invites.uses} - 1` })
+        .where(and(eq(invites.token, token), gt(invites.uses, 0)));
+};
+
+export const findUsableInvite = async (token: string) => {
+    const rows = await db
+        .select({
+            expiresAt: invites.expiresAt,
+            maxUses: invites.maxUses,
+            uses: invites.uses,
+            inviterId: users.id,
+            inviterName: users.name,
+            inviterImage: users.image,
+        })
+        .from(invites)
+        .innerJoin(users, eq(users.id, invites.createdBy))
+        .where(and(eq(invites.token, token), usable()))
+        .limit(1);
+
+    return rows[0] ?? null;
+};
+
+/** Used up and expired invites are of no use to anyone, so they are dropped. */
+export const deleteDeadInvites = async () => {
+    await db.delete(invites).where(or(lte(invites.expiresAt, new Date()), sql`${invites.uses} >= ${invites.maxUses}`));
+};