client.js

const express = require("express")
const bodyParser = require("body-parser")
const axios = require("axios").default
const { randomString, timeout } = require("./utils")
const url = require('url');

const config = {
	port: 9000,

	clientId: "my-client",
	clientSecret: "zETqHgl0d7ThysUqPnaFuLOmG1E=",
	redirectUri: "http://localhost:9000/callback",

	authorizationEndpoint: "http://localhost:9001/authorize",
	tokenEndpoint: "http://localhost:9001/token",
	userInfoEndpoint: "http://localhost:9002/user-info",
}
let state = ""

const app = express()
app.set("view engine", "ejs")
app.set("views", "assets/client")
app.use(timeout)
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))

/*
Your code here
*/

app.get('/authorize', (req, res) => {
  state = randomString();
  const u = new URL(config.authorizationEndpoint);
  u.searchParams.append('response_type', 'code'); 
  u.searchParams.append('client_id', config.clientId);
  u.searchParams.append('client_secret', config.clientSecret);
  u.searchParams.append('redirect_uri', config.redirectUri);
  u.searchParams.append('scope', 'permission:name permission:date_of_birth');
  u.searchParams.append('state', state); 
  console.log(u.href);
  res.redirect(u.href);

  /*
  let url = config.authorizationEndpoint + '/?' +
    'response_type=code&' +
    'client_id=' + encodeURIComponent(config.clientId) + '&' +
    'client_secret=' + encodeURIComponent(config.clientSecret) + '&' +
    'redirect_uri=' + encodeURIComponent(config.redirectUri) + '&' +
    'scope=permission:name permission:date_of_birth&' + 
    'state=' + encodeURIComponent(state); 
  res.redirect(url);
  */
});

app.get('/callback', (req, res) => {
  if (state !== req.query.state) {
    res.status(403).end();
    return;
  }
  axios({
    method: 'POST',
    url: config.tokenEndpoint,
    auth: {username: config.clientId, password: config.clientSecret},
    data: {code: req.query.code}
  }).then(response => {
    return axios({
      method: 'GET',
      url: config.userInfoEndpoint,
      headers: {authorization: "bearer " +response.data.access_token}
    }).then(response => {
      res.render("welcome", {user: response.data});
    });
    
  });
});

const server = app.listen(config.port, "localhost", function () {
	var host = server.address().address
	var port = server.address().port
})

// for testing purposes

module.exports = {
	app,
	server,
	getState() {
		return state
	},
	setState(s) {
		state = s
	},
}