server.js

const express = require('express');
const app = express();
const { resolve } = require('path');
// Copy the .env.example in the root into a .env file in this folder
require('dotenv').config({ path: './.env' });

// Ensure environment variables are set.
checkEnv();

const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY, {
  apiVersion: '2023-10-16',
  appInfo: { // For sample support and debugging, not required for production:
    name: "stripe-samples/accept-a-payment/prebuilt-checkout-page",
    version: "0.0.1",
    url: "https://github.com/stripe-samples"
  }
});

app.use(express.static(process.env.STATIC_DIR));
app.use(express.urlencoded({ extended: true }));
app.use(
  express.json({
    // We need the raw body to verify webhook signatures.
    // Let's compute it only when hitting the Stripe webhook endpoint.
    verify: function (req, res, buf) {
      if (req.originalUrl.startsWith('/webhook')) {
        req.rawBody = buf.toString();
      }
    },
  })
);

app.get('/', (req, res) => {
  const path = resolve(process.env.STATIC_DIR + '/index.html');
  res.sendFile(path);
});

// Fetch the Checkout Session to display the JSON result on the success page
app.get('/checkout-session', async (req, res) => {
  const { sessionId } = req.query;
  const session = await stripe.checkout.sessions.retrieve(sessionId);
  res.send(session);
});

app.post('/create-checkout-session', async (req, res) => {
  const domainURL = process.env.DOMAIN;

  // Create new Checkout Session for the order
  // Other optional params include:
  // For full details see https://stripe.com/docs/api/checkout/sessions/create
  const session = await stripe.checkout.sessions.create({
    mode: 'payment',
    line_items: [{
      price: process.env.PRICE,
      quantity: 1,
    }],
    // ?session_id={CHECKOUT_SESSION_ID} means the redirect will have the session ID set as a query param
    success_url: `${domainURL}/success.html?session_id={CHECKOUT_SESSION_ID}`,
    cancel_url: `${domainURL}/canceled.html`,
    // automatic_tax: { enabled: true }
  });

  return res.redirect(303, session.url);
});

// Webhook handler for asynchronous events.
app.post('/webhook', async (req, res) => {
  let event;

  // Check if webhook signing is configured.
  if (process.env.STRIPE_WEBHOOK_SECRET) {
    // Retrieve the event by verifying the signature using the raw body and secret.
    let signature = req.headers['stripe-signature'];

    try {
      event = stripe.webhooks.constructEvent(
        req.rawBody,
        signature,
        process.env.STRIPE_WEBHOOK_SECRET
      );
    } catch (err) {
      console.log(`⚠️  Webhook signature verification failed.`);
      return res.sendStatus(400);
    }
  } else {
    // Webhook signing is recommended, but if the secret is not configured in `.env`,
    // retrieve the event data directly from the request body.
    event = req.body;
  }

  if (event.type === 'checkout.session.completed') {
    console.log(`🔔  Payment received!`);

    // Note: If you need access to the line items, for instance to
    // automate fullfillment based on the the ID of the Price, you'll
    // need to refetch the Checkout Session here, and expand the line items:
    //
    // const session = await stripe.checkout.sessions.retrieve(
    //   'cs_test_KdjLtDPfAjT1gq374DMZ3rHmZ9OoSlGRhyz8yTypH76KpN4JXkQpD2G0',
    //   {
    //     expand: ['line_items'],
    //   }
    // );
    //
    // const lineItems = session.line_items;
  }

  res.sendStatus(200);
});

app.listen(4242, () => console.log(`Node server listening on port ${4242}!`));


function checkEnv() {
  const price = process.env.PRICE;
  if(price === "price_12345" || !price) {
    console.log("You must set a Price ID in the environment variables. Please see the README.");
    process.exit(0);
  }
}