Initial commit: PodcastYes — AI podcast platform

lib/usage/limits.ts

@@ -0,0 +1,51 @@
+import { getEffectivePlan } from "@/lib/billing/subscription";
+import { getUsage } from "./meter";
+import { PLANS, UNLIMITED, withinLimit, type PlanKey, type UsageMetric } from "@/lib/billing/plans";
+
+export interface LimitCheck {
+  allowed: boolean;
+  used: number;
+  limit: number; // UNLIMITED (-1) when uncapped
+  plan: PlanKey;
+  metric: UsageMetric;
+}
+
+/** Thrown by enforceLimit when a metric's monthly cap is reached. */
+export class LimitExceededError extends Error {
+  constructor(public check: LimitCheck) {
+    super(`Monthly ${check.metric} limit reached on the ${check.plan} plan`);
+    this.name = "LimitExceededError";
+  }
+}
+
+/** Read-only check of a metric against the subject's plan + current usage. */
+export async function checkLimit(
+  userId: string,
+  metric: UsageMetric,
+  activeOrgId?: string | null
+): Promise<LimitCheck> {
+  const { key, subjectId } = await getEffectivePlan(userId, activeOrgId);
+  const used = await getUsage(subjectId, metric);
+  return {
+    allowed: withinLimit(key, metric, used),
+    used,
+    limit: PLANS[key].limits[metric],
+    plan: key,
+    metric,
+  };
+}
+
+/** Throw LimitExceededError if the metric is over its cap. */
+export async function enforceLimit(
+  userId: string,
+  metric: UsageMetric,
+  activeOrgId?: string | null
+): Promise<LimitCheck> {
+  const check = await checkLimit(userId, metric, activeOrgId);
+  if (!check.allowed) throw new LimitExceededError(check);
+  return check;
+}
+
+export function isUnlimited(limit: number): boolean {
+  return limit === UNLIMITED;
+}