server.js

const cors = require('cors');
const path = require('path');
const express = require('express');
const bodyParser = require('body-parser');

if (process.env.NODE_ENV !== 'production') require('dotenv').config();

const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);

const app = express();
const port = process.env.PORT || 5000;

app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.use(cors());

if (process.env.NODE_ENV === 'production') {
  app.use(express.static(path.join(__dirname, 'client/build')));

  app.get('*', function (_req, res) {
    res.sendFile(path.join(__dirname, 'client/build', 'index.html'));
  });
}

app.get('/', (_req, res) => {
  res.send('Hi Stripe devs');
});

app.listen(port, error => {
  if (error) throw error;
  console.log('Server running on port ' + port);
});

const calculateOrderAmount = items => {
  const orderAmount = items.reduce(
    (acc, cartItem) => acc + cartItem.quantity * cartItem.price,
    0
  );

  return orderAmount * 100; // stripe charges in lowest denomination i.e cents for dollars, so convert to cents
};

app.post('/create-payment-intent', async (req, res) => {
  const { items } = req.body;

  // Create a PaymentIntent with the order amount and currency
  const paymentIntent = await stripe.paymentIntents.create({
    amount: calculateOrderAmount(items),
    currency: 'usd',
    automatic_payment_methods: {
      enabled: true,
    },
  });

  res.send({
    clientSecret: paymentIntent.client_secret,
  });
});

app.post('/payment', (req, res) => {
  const body = {
    source: req.body.token.id,
    amount: req.body.amount,
    currency: 'usd',
  };

  stripe.charges.create(body, (stripeErr, stripeRes) => {
    if (stripeErr) {
      res.status(500).send({ error: stripeErr });
    } else {
      res.status(200).send({ success: stripeRes });
    }
  });
});