Initial import of zappier-customer-service from zapier monorepo

src/nats-billing.js

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+export const SUBJECTS = {
+  STATEMENT_GET: 'verae.billing.statement.get',
+  BALANCE_ADJUST: 'verae.billing.balance.adjust',
+  AUTHZ_CHECK: 'verae.access.authz.check',
+};
+const PLANE = 'staff';
+
+async function authz(subject, payload) {
+  const http = process.env.AUTHZ_URL;
+  if (!http && !process.env.NATS_URL) return { allow: true, subject };
+  if (http) {
+    const r = await fetch(`${http.replace(/\/$/, '')}/check`, {
+      method: 'POST',
+      headers: { 'content-type': 'application/json' },
+      body: JSON.stringify({ plane: PLANE, subject, kind: payload?.kind, payload, principal: payload?.agent }),
+    });
+    return r.json();
+  }
+  return { allow: true, subject };
+}
+
+export async function billingRequest(subject, payload) {
+  const decision = await authz(subject, payload);
+  if (decision && decision.allow === false) {
+    const err = new Error(decision.reason || 'denied');
+    err.status = 403;
+    err.decision = decision;
+    throw err;
+  }
+  const url = process.env.NATS_URL;
+  if (!url) return null;
+  try {
+    const { connect, StringCodec } = await import('nats');
+    const nc = await connect({ servers: url.split(','), name: 'zappier-customer-service' });
+    const sc = StringCodec();
+    const m = await nc.request(subject, sc.encode(JSON.stringify({ ...payload, plane: PLANE })), { timeout: 2000 });
+    const out = JSON.parse(sc.decode(m.data) || '{}');
+    await nc.close();
+    return out;
+  } catch (err) {
+    if (err.status === 403) throw err;
+    return null;
+  }
+}

src/server.js

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+#!/usr/bin/env node
+/**
+ * CS HTTP front door. Internally prefers NATS account-balance, then HTTP.
+ */
+import fs from 'node:fs';
+import http from 'node:http';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { SUBJECTS, billingRequest } from './nats-billing.js';
+
+const PUBLIC = path.join(path.dirname(fileURLToPath(import.meta.url)), '..', 'public');
+
+const PORT = Number(process.env.PORT || 3011);
+const BOOKS = (process.env.ACCOUNT_BALANCE_URL || 'http://127.0.0.1:3010').replace(/\/$/, '');
+const EDGE = (process.env.ZAPPIER_ADMIN_URL || 'http://127.0.0.1:3000').replace(/\/$/, '');
+const KEY = process.env.ZAPPIER_ADMIN_KEY || 'admin-dev-key';
+
+async function statement(customerId) {
+  const nats = await billingRequest(SUBJECTS.STATEMENT_GET, { customerId });
+  if (nats) return { status: 200, body: { ...nats, source: 'nats' } };
+  const r = await fetch(`${BOOKS}/statement/${customerId}`);
+  if (r.ok) return { status: r.status, body: { ...(await r.json()), source: 'account-balance' } };
+  const e = await fetch(`${EDGE}/admin/api/statement/${customerId}`, { headers: { 'x-admin-key': KEY } });
+  return { status: e.status, body: { ...(await e.json().catch(() => ({}))), source: 'edge' } };
+}
+
+const server = http.createServer(async (req, res) => {
+  const url = new URL(req.url || '/', `http://127.0.0.1:${PORT}`);
+  const json = (code, obj) => {
+    res.writeHead(code, { 'content-type': 'application/json' });
+    res.end(JSON.stringify(obj));
+  };
+  try {
+    if (req.method === 'GET' && (url.pathname === '/' || url.pathname === '/index.html')) {
+      res.writeHead(200, { 'content-type': 'text/html; charset=utf-8' });
+      res.end(fs.readFileSync(path.join(PUBLIC, 'index.html')));
+      return;
+    }
+    if (req.method === 'GET' && url.pathname === '/health') {
+      return json(200, { ok: true, role: 'zappier-customer-service', nats: Boolean(process.env.NATS_URL) });
+    }
+    const review = url.pathname.match(/^\/review\/([^/]+)$/);
+    if (req.method === 'GET' && review) {
+      const out = await statement(review[1]);
+      return json(out.status, out.body);
+    }
+    if (req.method === 'POST' && url.pathname === '/credits') {
+      const chunks = [];
+      for await (const c of req) chunks.push(c);
+      const payload = JSON.parse(Buffer.concat(chunks).toString('utf8') || '{}');
+      const nats = await billingRequest(SUBJECTS.BALANCE_ADJUST, { ...payload, kind: 'credit' });
+      if (nats) return json(200, { ...nats, source: 'nats' });
+      const r = await fetch(`${BOOKS}/adjust`, {
+        method: 'POST',
+        headers: { 'content-type': 'application/json' },
+        body: JSON.stringify(payload),
+      });
+      const body = await r.json().catch(() => ({}));
+      await fetch(`${EDGE}/admin/api/credits`, {
+        method: 'POST',
+        headers: { 'content-type': 'application/json', 'x-admin-key': KEY },
+        body: JSON.stringify(payload),
+      }).catch(() => {});
+      return json(r.status, body);
+    }
+    if (req.method === 'GET' && url.pathname === '/credits') {
+      const id = url.searchParams.get('customerId');
+      if (!id) return json(400, { error: 'customerId required' });
+      const out = await statement(id);
+      return json(out.status, { credits: out.body.credits || [] });
+    }
+    json(404, { error: 'not found' });
+  } catch (err) {
+    json(err.status === 403 ? 403 : 502, { error: err.message, ...(err.decision || {}) });
+  }
+});
+
+server.listen(PORT, '0.0.0.0', () => {
+  process.stdout.write(`zappier-customer-service http://0.0.0.0:${PORT}/\n`);
+});