Initial import of zappier-edge from zapier monorepo

src/meter.ts

@@ -0,0 +1,48 @@
+import { RequestHandler } from 'express';
+import { PricingContext, Quote, quoteCall } from './pricing';
+import { UsageRepo } from './usage';
+
+export function meter(
+  endpointId: string,
+  repo: UsageRepo,
+  pricing: PricingContext,
+): RequestHandler {
+  return (req, res, next) => {
+    const customer = req.customer;
+    if (!customer) {
+      res.status(401).json({ error: 'unauthenticated' });
+      return;
+    }
+    const metadataBytes = Buffer.byteLength(
+      JSON.stringify(req.body?.metadata ?? {}),
+      'utf8',
+    );
+    const files = (req.files as Express.Multer.File[] | undefined) ?? [];
+    const attachmentBytes = files.reduce((sum, f) => sum + f.size, 0);
+
+    let quote: Quote;
+    try {
+      quote = quoteCall(
+        pricing,
+        customer.tierId,
+        endpointId,
+        { metadataBytes, attachmentBytes },
+        customer.multiplierOverride,
+      );
+    } catch (err) {
+      res.status(403).json({ error: (err as Error).message });
+      return;
+    }
+
+    repo.record({
+      customerId: customer.id,
+      endpointId,
+      cents: quote.totalCents,
+      metadataBytes,
+      attachmentBytes,
+      timestamp: new Date(),
+    });
+    res.locals.quote = quote;
+    next();
+  };
+}