Refactor to task

fp-test.js

const crypto = require('crypto');
const util = require('util');
const curry = require('lodash/curry');
const compose = require('lodash/flowRight'); // alias flowRight as compose
const moment = require('moment');
const Task = require('folktale/concurrency/task');
const { fromPromised, waitAll } = require('folktale/concurrency/task');
 

// isValidForgotPasswordRequest :: ForgotPasswordInput -> boolean 
const isValidForgotPasswordRequest = data =>
  data != null
  && data.usernameOrEmail != null
  && typeof data.usernameOrEmail == 'string'
  && data.usernameOrEmail.length > 0;
 
// usernameOrEmailExists :: ForgotPasswordInput -> Task string
const usernameOrEmailExists = data => isValidForgotPasswordRequest(data)
  ? Task.of(data.usernameOrEmail)
  : Task.rejected('No username or email');

// toHex :: Buffer -> string
const toHex = b => b.toString('hex');

// getRandomBytes :: () -> Promise Buffer
const getRandomBytes = util.promisify(crypto.randomBytes);

// getExpiration :: () -> number
const getExpiration = () => moment().add(1, 'h').unix();

// genToken :: () -> Task string
const genToken = curry((n, o) =>
  fromPromised(() =>
    getRandomBytes(n + o).then(toHex)
  )()
);



const paginationHasUser = pagedData =>
  pagedData != null && pagedData.total > 0 && pagedData.data.length > 0;

const checkUser = pagedData =>
  paginationHasUser(pagedData)
    ? Task.of(pagedData.data[0])
    : Task.rejected('No user found');

// teset data to puke out
let testUser = {
  id: 1,
  email: 'test@test.com',
  username: 'admin',
  resetToken: null,
  resetTokenExpiration: null
};

const queryUser = un =>
  un == 'admin'
    ? Promise.resolve({ total: 1, data: [ testUser ] })
    : Promise.resolve({ total: 0, data: [] });

// simulate db query that returns a promise
// fetchUser :: string -> Task User
const fetchUser = fromPromised(queryUser);
 
// run fetching user and generating token in parallel,
//  to test that out / learn how to use tasks better
// getUsernameAndToken :: (getUser) -> (getToken) -> Task string -> Task [ PagedUser, string ]
const getUsernameAndToken = curry((getUser, getToken, task_un) =>
  task_un.chain(un => waitAll([ getUser(un), getToken(5) ])));


// assignToken :: Task [ User, string ] -> Task User
const assignToken = tsk =>
  tsk.map(([ user, token ]) => {
    user.resetToken = token;
    user.resetTokenExpiration = getExpiration();

    return user;
  });

// userExists :: Task [ PagedUser, token ] -> Task [ User, token ] 
const userExists = userAndToken =>
  userAndToken.chain(([ pagedUser, token ]) =>
    checkUser(pagedUser).map(user => [ user, token ]));


// TODO after successful chainTokenAssign, we can
//  email user (call microservice)

// compose it all together!
// f :: ForgotPasswordInput -> (string eventually, for now it is whatever object)
let f = compose(assignToken, userExists, getUsernameAndToken(fetchUser, genToken(30)), usernameOrEmailExists);
 


// TODO could probably wrap argv access up in some functional code
f({ usernameOrEmail: process.argv.slice(2)[0] })
  .run().promise()
  .then(user =>
    console.log(`Hello user number ${user.id}, your reset token is: ${user.resetToken}\nThis will expire at ${moment(user.resetTokenExpiration).toString()}`
  ))
  .catch(console.error);

To run, drop the code in a folder and install, then pass it with a username

npm i --save lodash folktale moment
node fp-test.js
node fp-test.js admin