monzo-auth.js

'use strict'

// const yargs = require('yargs')
const express = require('express')
const request = require('request')
const uuid = require('node-uuid')
const querystring = require('querystring')
const opener = require('opener')

let argv = require('yargs')
             .option('client_id', {
               alias: 'id',
               type: 'string',
               required: true
             })
             .option('client_secret', {
               alias: 'secret',
               type: 'string',
               required: true
             })
             .option('auth_url', {
               alias: 'auth',
               type: 'string',
               default: 'auth.getmondo.co.uk'
             })
             .option('api_domain', {
               alias: 'api',
               type: 'string',
               default: 'api.monzo.com'
             })
             .option('state', {
               type: 'string'
             })
             .option('port', {
               alias: 'p',
               type: 'number',
               default: 0
             })
             .option('exit', {
               alias: 'x',
               type: 'boolean',
               default: true
             })
             .argv

const clientId = argv.client_id
const clientSecret = argv.client_secret

const authUrl = `https://${argv.auth_url}`
const apiDomain = `https://${argv.api_domain}`
const apiTokenUrl = '/oauth2/token'

const app = express()
const server = require('http').createServer(app)

const exitImmediately = argv.exit
let port = argv.port
let state = argv.state


function getRootAddress (url) {
  url = url || ''
  return `http://localhost:${port}${url}`
}

function getAuthAddress () {
  return getRootAddress('/monzo')
}

app.use('/monzo', (req, res) => {
  if (req.query.state !== state) {
    res.json({
      error: 'State does not match',
      state: state,
      query: req.query
    })
  }
  request({
    uri: `${apiDomain}${apiTokenUrl}`,
    method: 'POST',
    json: true,
    form: {
      grant_type: 'authorization_code',
      client_id: clientId,
      client_secret: clientSecret,
      redirect_uri: getAuthAddress(),
      code: req.query.code
    }
  }, (err, data) => {
    if (err) {
      res.status(500)
      res.json(err)
    }
    if (data) {
      res.json(data.body)
    }
    if (exitImmediately) {
      process.exit()
    }
  })
})

app.use('/', (req, res) => {
  state = req.query.state || uuid.v4()
  let params = {
    client_id: clientId,
    redirect_uri: getAuthAddress(),
    response_type: 'code',
    state: state
  }
  let qs = querystring.stringify(params)
  res.redirect(`${authUrl}?${qs}`)
})

server.listen(port, function () {
  console.log('Monzo auth process started')
  port = server.address().port
  opener(getRootAddress())
})