app.js

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

const app = express();

// Convenience middleware to parse JSON body
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

// These credentials should be received from the onboarding team.
// These are account specific credentials

const { API_KEY, IDENTITY_API_URL, GATEWAY_API_URL, PORT, REALM } = process.env;

if (!API_KEY || !IDENTITY_API_URL || !GATEWAY_API_URL) {
  console.error("Error!!! Env configs not found");
  process.exit();
}

app.get('/health', (_, res) => res.send('App working'));

/* 
  Example route that handles order creation, a similar route should be implemented
  on your server to create orders and the response should be sent to the client 
*/
app.post('/api/createOrder', async (req, res) => {

  // Authenticate and receive bearer token
  try {

    const { data } = await axios({
      method: 'post',
      url: IDENTITY_API_URL,
      headers: {
        'Content-Type': 'application/vnd.ni-identity.v1+json',
        'Authorization': `Basic ${API_KEY}`
      },
      data: {
        grant_type: 'client_credentials',
        realm: REALM,
      }
    });

    const { access_token } = data;

    // Create the order using the bearer token received from previous step and the order data received from client
    // Refer docs for the possible fields available for order creation

    const { data: orderData } = await axios.post(GATEWAY_API_URL, {
      ...req.body
    }, {
      headers: {
        'Authorization': `Bearer ${access_token}`, // Note the access_token received in the previous step is passed here
        'Content-Type': 'application/vnd.ni-payment.v2+json',
        'Accept': 'application/vnd.ni-payment.v2+json'
      },
    },
    );

    res
      .status(200)
      .send(orderData)

  } catch (error) {
    console.error(error);
    res
      .status(400)
      .send({
        error,
        message: 'An error occured',
      });
  }
});

app.listen(PORT || 3000, () => console.log(`Example app listening on port ${PORT}!`));