africastalking/lib/ussd.js

Official AfricasTalking node.js API wrapper

'use strict'

const Joi = require('joi')
const urlencoded = require('body-parser/urlencoded')

// as per specs http://docs.africastalking.com/ussd
const CONTENT_TYPE = 'text/plain'
const SESSION_CONTINUE = 'CON '
const SESSION_END = 'END '
const RESPONSE_CODE = 200

/**
 *
 * @param handler
 * @returns {*[]} Connect/express middleware
 * @constructor
 */
function ExpressHandler (handler) {
  return [ // connect/express middleware
    urlencoded({ extended: false }),
    function (req, res, next) {
      try {
        const payload = req.body
        handler(payload, (opts) => {
          const schema = Joi.object({
            response: Joi.string().required()
              .messages({
                'any.required': '"response" is required',
                'string.base': '"response" must be a string'
              }),
            endSession: Joi.boolean().required()
              .messages({
                'any.required': '"endSession" is required',
                'boolean.base': '"endSession" must be true or false'
              })
          })

          const { error } = schema.validate(opts, { abortEarly: false })

          // express uses next(err) to pass back errors
          if (error) {
            const messages = error.details.map(detail => detail.message)
            return next(messages)
          }

          let response = opts.response

          if (opts.endSession) {
            response = SESSION_END + response
          } else {
            response = SESSION_CONTINUE + response
          }
          res.contentType(CONTENT_TYPE)
          res.status(RESPONSE_CODE).send(response)
        })
      } catch (ex) {
        next(ex)
      }
    }
  ]
}

// TODO: Helpers for other frameworks?

module.exports = ExpressHandler