// array of integers
const integerArr = [];
const intLen = 999999;
for (let i = 0; i < intLen; i++) {
  integerArr[i] = i + 1;
};

// array of objects
// age, gender and isProgrammer property values are
// decided at random
const peopleArr = [];
const peopLen = 99999;
for (let i = 0; i < peopLen; i++) {
  const obj = {
    name: 'Alex',
    age: Math.floor(Math.random() * 100),
    gender: Math.floor(Math.random() * 2) === 1 ? 'male' : 'female',
    isProgrammer: Math.floor(Math.random() * 2) === 1
  }

  peopleArr[i] = obj;
}

// export these arrays so we can use them in our test script
module.exports = {
  integerArr,
  peopleArr
};

const {performance} = require('perf_hooks');
const {reduce, map, filter} = require('lodash');
const {integerArr, peopleArr} = require('./data');

// helper function, which receives a function to perform,
// invokes that function, and returns the time taken to perform
function perfTest(test) {
  const start = performance.now();
  test();
  const end = performance.now();

  return (end - start).toFixed(3);
}

// a helper function which logs the time between 2 tests
function logTimes(time1, time2) {
  console.log(time1);
  console.log(time2);
}

// each function returns an object of 2 methods
// 1. the test to perform on the integer array
// 2. the test to perform on the object array

// FILTERS
// 1. filter on even numbers
// 2. filter on females
function myFilters() {
  return {
    int: function(num) {
      return num % 2 === 0;
    },

    obj: function(person) {
      return person.gender === 'female';
    }
  }
}

// MAPS
// 1. multiply each value by 2
// 2. add a further property to object, isGodly, which is determined
// by whether the person is a programmer or not
function myMaps() {
  return {
    int: function(num) {
      return num * 2;
    },

    obj: function(person) {
      person.isGodly = person.isProgrammer;

      return person;
    }
  }
}

// REDUCE
// 1. return the sum of elements
// 2. return the sum of ages of people
function myReduces() {
  return {
    int: function(sum, num) {
      return sum += num;
    },

    obj: function(sum, person) {
      return sum += person.age;
    }
  }
}

// invoke each test so we can easily access the individual tests
const filterTests = myFilters();
const mapTests = myMaps();
const reduceTests = myReduces();

/************ ROUND 1: FILTER *****************/
// lodash integer filter vs vanilla integer filter
const ft1 = perfTest(() => filter(integerArr, filterTests.int));
const ft2 = perfTest(() => integerArr.filter(filterTests.int));

// lodash object filter vs vanilla object filter
const ft3 = perfTest(() => filter(peopleArr, filterTests.obj));
const ft4 = perfTest(() => peopleArr.filter(filterTests.obj));


/************ ROUND 2: MAP ********************/
// lodash integer map vs vanilla integer map
const mt1 = perfTest(() => map(integerArr, mapTests.int));
const mt2 = perfTest(() => integerArr.map(mapTests.int));

// lodash object map vs vanilla object map
const mt3 = perfTest(() => map(peopleArr, mapTests.obj));
const mt4 = perfTest(() => peopleArr.map(mapTests.obj));


/************ ROUND 3: REDUCE *****************/
// lodash integer reduce vs vanilla integer reduce
const rt1 = perfTest(() => reduce(integerArr, reduceTests.int));
const rt2 = perfTest(() => integerArr.reduce(reduceTests.int));

// lodash object reduce vs vanilla object reduce
const rt3 = perfTest(() => reduce(peopleArr, reduceTests.obj));
const rt4 = perfTest(() => peopleArr.reduce(reduceTests.obj))

/************* RESULTS ************* */
console.log('MAP INTEGER');
logTimes(mt1, mt2);

console.log('MAP OBJECT');
logTimes(mt3, mt4);

console.log('FILTER INTEGER');
logTimes(ft1, ft2);

console.log('FILTER OBJECT');
logTimes(ft3, ft4);

console.log('REDUCE INTEGER');
logTimes(rt1, rt2);

console.log('REDUCE OBJECT');
logTimes(rt3, rt4);