refactoring-video-store-js

index.js

const arraySum = prop => arr =>
  arr.reduce((acc, r) => acc + r[prop], 0)

const amountByCode = r => ({
  'regular': 2 + (r.days > 2 ? ((r.days - 2) * 1.5) : 0),
  'new': r.days * 3,
  'childrens': 1.5 + (r.days > 3 ? ((r.days - 3) * 1.5) : 0),
})

const frequentRenterPointsByCode = r => ({
  'regular': 1,
  // add bonus for a two day new release rental
  'new': r.days > 2 ? 2 : 1,
  'childrens': 1
})

const buildRecord = movies => r => {
  const movie = movies[r.movieID]
  const amounts = amountByCode(r)
  const points = frequentRenterPointsByCode(r)
  return {
    movie,
    amount: amounts[movie.code],
    points: points[movie.code],
  }
}

const print = (customer, records) => {
  const sumAmounts = arraySum('amount')
  const sumPoints = arraySum('points')
  
  const amounts = 
    records
    .map(r => `\t${r.movie.title}\t${r.amount}\n`)
    .join('')

  return (
    `Rental Record for ${customer.name}\n` +
    amounts +
    `Amount owed is ${sumAmounts(records)}\n` +
    `You earned ${sumPoints(records)} frequent renter points\n`
  )
}

function statement(customer, movies) {
  const records =
    customer.rentals
    .map(buildRecord(movies))

  return print(customer, records)
}

module.exports = statement

test.js

const assert = require('assert')
const statement = require('./index')

const MOVIES = {
  F001: { title: 'Ran', code: 'regular'},
  F002: { title: 'Trois Couleurs: Bleu', code: 'regular'},
  F003: { title: 'Logan', code: 'new' },
  F004: { title: 'Robin Hood', code: 'childrens' },
}

const customer1 = {
  name: 'martin',
  rentals: [
    { movieID: 'F001', days: 3 },
    { movieID: 'F002', days: 1 },
  ]
}

const output1 =
'Rental Record for martin' +
'\n\tRan\t3.5' +
'\n\tTrois Couleurs: Bleu\t2' +
'\nAmount owed is 5.5' +
'\nYou earned 2 frequent renter points' +
'\n'

const customer2 = {
  name: 'fede',
  rentals: [
    { movieID: 'F003', days: 4 },
    { movieID: 'F004', days: 5 },
  ]
}

const output2 =
'Rental Record for fede' +
'\n\tLogan\t12' +
'\n\tRobin Hood\t4.5' +
'\nAmount owed is 16.5' +
'\nYou earned 3 frequent renter points' +
'\n'

const customer3 = {
  name: 'rob',
  rentals: [
    { movieID: 'F001', days: 1 },
    { movieID: 'F004', days: 2 },
  ]
}

const output3 =
'Rental Record for rob' +
'\n\tRan\t2' +
'\n\tRobin Hood\t1.5' +
'\nAmount owed is 3.5' +
'\nYou earned 2 frequent renter points' +
'\n'

describe('statement', () => {

  it('should print statement for customer 1', () => {
    assert.equal(output1, statement(customer1, MOVIES))
  })

  it('should print statement for customer 2', () => {
    assert.equal(output2, statement(customer2, MOVIES))
  })

  it('should print statement for customer 3', () => {
    assert.equal(output3, statement(customer3, MOVIES))
  })

})