SaaS Monetization & Stripe Integration: Subscription Management & Billing

// Production Express Stripe Webhook Handler
import express from 'express';
import Stripe from 'stripe';
import { db } from './db';

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, { apiVersion: '2023-10-16' });
const app = express();

app.post('/api/webhooks/stripe', express.raw({ type: 'application/json' }), async (req, res) => {
  const sig = req.headers['stripe-signature']!;
  let event: Stripe.Event;

  try {
    event = stripe.webhooks.constructEvent(req.body, sig, process.env.STRIPE_WEBHOOK_SECRET!);
  } catch (err: any) {
    return res.status(400).send(`Signature Verification Failed: ${err.message}`);
  }

  const processed = await db.query('SELECT id FROM processed_events WHERE id = $1', [event.id]);
  if (processed.rows.length > 0) {
    return res.json({ received: true, status: 'already_processed' });
  }

  switch (event.type) {
    case 'invoice.payment_succeeded':
      await handleInvoicePaid(event.data.object as Stripe.Invoice);
      break;
    case 'customer.subscription.deleted':
      await handleSubscriptionCanceled(event.data.object as Stripe.Subscription);
      break;
  }

  await db.query('INSERT INTO processed_events (id, created_at) VALUES ($1, NOW())', [event.id]);
  res.json({ received: true });
});