functional.js

/**
 * @author Oleg Kubrakov yellowred.github.com
 * @since 2017
 **/

const Promise = require('Bluebird')
const jwt = require('jsonwebtoken');


let generateOneTimeToken = (value) => {
  // we use promise to stub a request to MongoDB
  let token = jwt.sign({ value }, 'privkey');
  return Promise.resolve({value, token});
}

let data = [
  {
    name: "Michelle Rung",
    contacts: [
      { phone: "7281681726" },
      { emailAddress: "michelle@gmail.com" },
      { emailAddress: "michelle@gmail.com" },
      { emailAddress: "" }
    ]
  },
  {
    name: "Johann Sigh",
    contacts: [
      { phone: "7812787-2667" },
      { emailAddress: "johann@gmail.com" },
      { emailAddress: "johann-md@gmail.com" }
    ]
  }
]
let generateResponse = (data) => {
  return Promise.coroutine(function* () {

    let emails = data
                    .map(getEmailsFromIndividual)
                    .reduce(flatten)
                    .filter(value => value != undefined && value != "")
                    .filter(distinct)

    return yield Promise.map(
                            emails,
                            emailAddress => valueAndToken(emailAddress)
                          )
  })()
}

let getEmailsFromIndividual = (individual) => {
    if (!Array.isArray(individual.contacts)) return []
    return individual
            .contacts
            .map(value => value['emailAddress'])
}

let flatten = (flatArray, arrayElement) => {
  return flatArray.concat(arrayElement)
}

let distinct = (val, index, contacts) => {
  return contacts.indexOf(val) === index
}

let valueAndToken = (emailAddress) => {
  return generateOneTimeToken(emailAddress)
          .then(tokenObject => {
            return {
              electronicAddress: emailAddress,
              token: tokenObject.token
            }
          })
}
generateResponse(data).then(console.log)