Initial import of verae-middleware from zapier monorepo

src/store/usage.js

@@ -0,0 +1,102 @@
+/**
+ * @fileoverview Per-tenant usage metering counters.
+ * @module store/usage
+ */
+
+import { getStore, persist } from './db.js';
+import { getTenant, resolveLimits } from './tenants.js';
+import { createDebugger } from '../debug/logger.js';
+
+const log = createDebugger('billing');
+
+/**
+ * @returns {string} YYYY-MM period key
+ */
+function currentPeriod() {
+  const d = new Date();
+  return `${d.getUTCFullYear()}-${String(d.getUTCMonth() + 1).padStart(2, '0')}`;
+}
+
+/**
+ * @param {string} tenantId
+ * @returns {{ period: string, timestamps: number, verifications: number, statusChecks: number, batchTimestamps: number, overage: object }}
+ */
+function emptyUsage(tenantId) {
+  return {
+    tenantId,
+    period: currentPeriod(),
+    timestamps: 0,
+    verifications: 0,
+    statusChecks: 0,
+    batchTimestamps: 0,
+    overage: { timestamps: 0, verifications: 0 },
+  };
+}
+
+/**
+ * Get usage for tenant, rolling period if month changed.
+ * @param {string} tenantId
+ * @returns {ReturnType<typeof emptyUsage>}
+ */
+export function getUsage(tenantId) {
+  const store = getStore();
+  let usage = store.usage[tenantId];
+  const period = currentPeriod();
+
+  if (!usage || usage.period !== period) {
+    usage = emptyUsage(tenantId);
+    store.usage[tenantId] = usage;
+  }
+
+  return usage;
+}
+
+/**
+ * Public summary for /auth/me.
+ * @param {string} tenantId
+ * @returns {object}
+ */
+export function getUsageSummary(tenantId) {
+  const usage = getUsage(tenantId);
+  const tenant = getTenant(tenantId);
+  const limits = tenant ? resolveLimits(tenant) : null;
+
+  return {
+    period: usage.period,
+    timestamps: usage.timestamps,
+    verifications: usage.verifications,
+    statusChecks: usage.statusChecks,
+    batchTimestamps: usage.batchTimestamps,
+    limits: limits
+      ? {
+          timestamps: limits.timestamps,
+          verifications: limits.verifications,
+          batch: limits.batch,
+          batchMaxItems: limits.batchMaxItems,
+        }
+      : null,
+  };
+}
+
+/**
+ * Increment a usage metric.
+ *
+ * @param {string} tenantId
+ * @param {string} metric - e.g. `timestamps`, `verifications`, `statusChecks`, `batchTimestamps`, `overage.timestamps`
+ * @param {number} [amount=1]
+ * @returns {void}
+ */
+export function incrementUsage(tenantId, metric, amount = 1) {
+  const usage = getUsage(tenantId);
+
+  if (metric.startsWith('overage.')) {
+    const key = metric.slice('overage.'.length);
+    usage.overage[key] = (usage.overage[key] ?? 0) + amount;
+  } else {
+    usage[metric] = (usage[metric] ?? 0) + amount;
+  }
+
+  getStore().usage[tenantId] = usage;
+  persist();
+  log.debug('usage incremented', { tenantId, metric, amount, value: usage[metric] ?? usage.overage });
+}