'use strict';

let num = 4444444444444444 ; // not valid

let num1 = 1000111111111110 ; //not valid

let num2 = 9999999999999991 ; //not valid

let num3 = 8899777755550000 ; //vaild

let num4 = 5554446669991666 ; //valid

checkCard(num);

checkCard(num1);

checkCard(num2);

checkCard(num3);

checkCard(num4)

function checkCard(creditNum){

// it must be 16 numbers

let length ;

// change the number to a string so it has length property

let creditNumString = creditNum.toString();

//change the number to an array that so it has one string of the number

let creditNumArr = creditNumString.split(',');

// check if the number has 16 digits

if (creditNumString.length< 16 || creditNumString.length > 16) {

length = false;

} else {

length = true;

}

// The final digit must be even

let finalIsEven;

if (creditNumString[15] % 2 === 0) {

finalIsEven = true;

} else {

finalIsEven = false;

}

// The sum of all the digits must be greater than 16

let sumHigherThan16

// to be able to sum the numbers, must to make it an arry

let creditNumArrOfStrings = [];

for (var i = 0; i < creditNumString.length; i++) {

creditNumArrOfStrings.push(parseFloat(creditNumString[i]));

}

// this calculates the numbers

const reducer = (accumulator, currentValue) => accumulator + currentValue;

const sum = creditNumArrOfStrings.reduce(reducer);

if (sum <= 16) {

sumHigherThan16 = false;

} else {

sumHigherThan16 = true;}

// the digits cannot be the same

let notTheSameNum ;

// make it an arry

const allEqual = creditNumArrOfStrings => creditNumArrOfStrings.every( v => v === creditNumArrOfStrings[0] );

if (allEqual(creditNumArrOfStrings)) {

notTheSameNum = false;

} else {

notTheSameNum = true;

}

if (length && notTheSameNum && finalIsEven && sumHigherThan16) {

console.log('Valid credit card Number');

} else { console.log(`${creditNum} is not valid. Please enter another number`);

}

}