Initial import of zappier-edge from zapier monorepo

src/reports.ts

@@ -0,0 +1,98 @@
+import { BillingType, Customer } from './auth';
+import { TierConfig } from './pricing';
+import { UsageEntry } from './usage';
+
+export interface BillingRow {
+  customerId: string;
+  name: string;
+  billingType: BillingType;
+  calls: number;
+  totalCents: number;
+  creditCents: number;
+  billableCents: number;
+}
+
+/**
+ * Per-customer billing aggregation. Range is inclusive `from`, exclusive `to`;
+ * omit both for all time. Every customer matching the filters appears, even
+ * with zero usage.
+ */
+export function billingRows(args: {
+  entries: UsageEntry[];
+  customers: Customer[];
+  tiers: TierConfig[];
+  from?: Date;
+  to?: Date;
+  customerId?: string;
+  billingType?: BillingType;
+}): BillingRow[] {
+  const { entries, customers, tiers, from, to, customerId, billingType } = args;
+  const inRange = entries.filter(
+    (e) => (!from || e.timestamp >= from) && (!to || e.timestamp < to),
+  );
+  return customers
+    .filter((c) => (customerId ? c.id === customerId : true))
+    .filter((c) => (billingType ? (c.billingType ?? 'stripe') === billingType : true))
+    .map((c) => {
+      const mine = inRange.filter((e) => e.customerId === c.id);
+      const totalCents = mine.reduce((sum, e) => sum + e.cents, 0);
+      const tier = tiers.find((t) => t.id === c.tierId);
+      const creditCents = Math.min(totalCents, tier?.monthlyCreditCents ?? 0);
+      return {
+        customerId: c.id,
+        name: c.name,
+        billingType: c.billingType ?? 'stripe',
+        calls: mine.length,
+        totalCents,
+        creditCents,
+        billableCents: totalCents - creditCents,
+      };
+    });
+}
+
+export interface TrendPoint {
+  /** Day bucket: YYYY-MM-DD. Week bucket: the Monday (UTC) of that week, YYYY-MM-DD. */
+  bucket: string;
+  calls: number;
+  cents: number;
+}
+
+export function usageTrend(entries: UsageEntry[], bucket: 'day' | 'week'): TrendPoint[] {
+  const key = (d: Date): string => {
+    const day = new Date(d);
+    day.setUTCHours(0, 0, 0, 0);
+    if (bucket === 'week') {
+      // Shift back to Monday (ISO weeks start Monday; getUTCDay: Sun=0).
+      const dow = (day.getUTCDay() + 6) % 7;
+      day.setUTCDate(day.getUTCDate() - dow);
+    }
+    return day.toISOString().slice(0, 10);
+  };
+  const buckets = new Map<string, TrendPoint>();
+  for (const e of entries) {
+    const k = key(e.timestamp);
+    const point = buckets.get(k) ?? { bucket: k, calls: 0, cents: 0 };
+    point.calls += 1;
+    point.cents += e.cents;
+    buckets.set(k, point);
+  }
+  return [...buckets.values()].sort((a, b) => a.bucket.localeCompare(b.bucket));
+}
+
+export interface CsvColumn {
+  key: string;
+  label: string;
+}
+
+/** RFC 4180 CSV with a header row. Values containing , " or newlines are quoted. */
+export function toCsv<T extends object>(rows: T[], columns: CsvColumn[]): string {
+  const cell = (v: unknown): string => {
+    const s = String(v ?? '');
+    return /[",\n\r]/.test(s) ? `"${s.replace(/"/g, '""')}"` : s;
+  };
+  const lines = [columns.map((c) => cell(c.label)).join(',')];
+  for (const row of rows) {
+    lines.push(columns.map((c) => cell((row as Record<string, unknown>)[c.key])).join(','));
+  }
+  return lines.join('\n');
+}