redefined-designs/backend/src/app.ts

import express, { Request, Response, NextFunction } from 'express';
import cookieParser from 'cookie-parser';
import path from 'path';
import itemsRouter from './routes/items';
import { router as cartCheckoutRouter, webhookRouter as cartCheckoutWebhookRouter } from './routes/cartCheckout';
import adminRouter from './routes/admin';
import adminCustomersRouter from './routes/adminCustomers';
import adminSettingsRouter from './routes/adminSettings';
import adminEmailTemplatesRouter from './routes/adminEmailTemplates';
import adminCategoriesRouter from './routes/adminCategories';
import adminTagsRouter from './routes/adminTags';
import adminVersionRouter from './routes/adminVersion';
import filtersRouter from './routes/filters';
import customersRouter from './routes/customers';
import publicRouter from './routes/public';
import cartRouter from './routes/cart';
import shippingAddressesRouter from './routes/shippingAddresses';
import clientErrorsRouter from './routes/clientErrors';
import { attachCustomer } from './middleware/customerAuth';
import { requireAdminGate } from './middleware/adminGate';
import { asyncRoute } from './asyncRoute';
import { uploadsRouter } from './uploads';

const app = express();
// Express advertises itself in X-Powered-By by default, which hands an
// attacker the server stack for free when picking exploits to try.
app.disable('x-powered-by');
app.set('trust proxy', 1);

app.use('/webhooks/paypal', express.json(), cartCheckoutWebhookRouter);
app.use(express.json());
app.use(cookieParser());
// Wrapped like any route: attachCustomer awaits a session lookup, and mounted
// globally an unforwarded rejection here would hang every request in the app —
// including the routes that wrap their own handlers correctly.
app.use(asyncRoute(attachCustomer));
app.use('/uploads', uploadsRouter(process.env.UPLOADS_DIR || '/app/uploads'));

// Trimmed with a loop rather than a `/+$/` regex, which backtracks.
function trimTrailingSlashes(value: string): string {
  let trimmed = value;
  while (trimmed.endsWith('/')) trimmed = trimmed.slice(0, -1);
  return trimmed;
}

app.get('/api/config', (_req, res) => {
  const clientId = process.env.PAYPAL_CLIENT_ID;
  const isPlaceholder = !clientId || clientId.length < 10 || clientId === 'REPLACE_WITH_PAYPAL_CLIENT_ID';
  res.json({
    paypalClientId: isPlaceholder ? null : clientId,
    demoMode: process.env.DEMO_MODE !== 'false',
    currency: process.env.SITE_CURRENCY || 'USD',
    // Where uploaded images should be fetched from (#103). Empty means the
    // app's own origin, which is both the default and what local development
    // has — there is no second hostname on a laptop. Set it to a hostname of
    // its own in production and user-supplied files stop sharing an origin with
    // the application, which is the whole unit of trust in a browser.
    //
    // Sent at runtime rather than built in, so one image serves every
    // environment, the same reason paypalClientId and demoMode are here.
    //
    // Trailing slash trimmed so callers can join with a stored path, which
    // always begins with one, without producing a double.
    uploadsBaseUrl: trimTrailingSlashes(process.env.UPLOADS_BASE_URL ?? '')
  });
});

app.use('/api/items', itemsRouter);
app.use('/api/filters', filtersRouter);
app.use('/api/cart', cartRouter);
app.use('/api/checkout/cart', cartCheckoutRouter);
// requireAdminGate is attached to each admin router rather than to a path
// prefix. Attached to the router, an admin router added later at some other
// path still inherits it — and since the proxy only injects the header on the
// paths its regex matches, that router refuses loudly on its first request
// instead of being quietly public. See middleware/adminGate.ts and #63.
app.use('/api/admin/customers', requireAdminGate, adminCustomersRouter);
app.use('/api/admin/settings', requireAdminGate, adminSettingsRouter);
app.use('/api/admin/email-templates', requireAdminGate, adminEmailTemplatesRouter);
app.use('/api/admin/categories', requireAdminGate, adminCategoriesRouter);
app.use('/api/admin/tags', requireAdminGate, adminTagsRouter);
app.use('/api/admin/version', requireAdminGate, adminVersionRouter);
app.use('/api/admin', requireAdminGate, adminRouter);
app.use('/api/customers/me/addresses', shippingAddressesRouter);
app.use('/api/customers', customersRouter);
app.use('/api/client-errors', clientErrorsRouter);
app.use('/', publicRouter);

if (process.env.NODE_ENV !== 'test') {
  const staticDir = path.join(__dirname, '..', 'public');
  app.use(express.static(staticDir));
  app.get('*', (_req, res) => {
    res.sendFile(path.join(staticDir, 'index.html'));
  });
}

// Mounted last, so it sees errors from every route above. Without it, a route
// that hands an error to next() falls through to Express's default handler,
// and — worse — an async route that rejects never responds at all, leaving the
// client hanging. A hung request is indistinguishable from an empty catalogue
// in the UI, which is exactly how a schema mismatch once read as "the store
// has no items". Always answer.
//
// The four-argument signature is what marks this as error middleware; `next`
// is unused but must stay for Express to recognise it.
// eslint-disable-next-line @typescript-eslint/no-unused-vars
app.use((err: Error, _req: Request, res: Response, _next: NextFunction) => {
  console.error(err);
  if (res.headersSent) return;
  res.status(500).json({ error: 'internal error' });
});

export default app;