script.js

// All valid credit card numbers
const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8];
const valid2 = [5, 5, 3, 5, 7, 6, 6, 7, 6, 8, 7, 5, 1, 4, 3, 9];
const valid3 = [3, 7, 1, 6, 1, 2, 0, 1, 9, 9, 8, 5, 2, 3, 6];
const valid4 = [6, 0, 1, 1, 1, 4, 4, 3, 4, 0, 6, 8, 2, 9, 0, 5];
const valid5 = [4, 5, 3, 9, 4, 0, 4, 9, 6, 7, 8, 6, 9, 6, 6, 6];

// All invalid credit card numbers
const invalid1 = [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5];
const invalid2 = [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3];
const invalid3 = [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4];
const invalid4 = [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5];
const invalid5 = [5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4];

// Can be either valid or invalid
const mystery1 = [3, 4, 4, 8, 0, 1, 9, 6, 8, 3, 0, 5, 4, 1, 4];
const mystery2 = [5, 4, 6, 6, 1, 0, 0, 8, 6, 1, 6, 2, 0, 2, 3, 9];
const mystery3 = [6, 0, 1, 1, 3, 7, 7, 0, 2, 0, 9, 6, 2, 6, 5, 6, 2, 0, 3];
const mystery4 = [4, 9, 2, 9, 8, 7, 7, 1, 6, 9, 2, 1, 7, 0, 9, 3];
const mystery5 = [4, 9, 1, 3, 5, 4, 0, 4, 6, 3, 0, 7, 2, 5, 2, 3];

// An array of all the arrays above
const batch = [valid1, valid2, valid3, valid4, valid5, invalid1, invalid2, invalid3, invalid4, invalid5, mystery1, mystery2, mystery3, mystery4, mystery5];

// Add your functions below:
const validateCred = (arr) => {
  let checkedArr = [];
  let checkDigit = arr[arr.length - 1]; // Store the check digit separately

  for (let i = arr.length - 2; i >= 0; i--) {
    if ((arr.length - i) % 2 === 0) {
      let doubleDigit = arr[i] * 2;

      if (doubleDigit > 9) {
        doubleDigit -= 9;
      }

      checkedArr.push(doubleDigit);
    } else {
      checkedArr.push(arr[i]);
    }
  }

  checkedArr.push(checkDigit);

  let sum = checkedArr.reduce((acc, curr) => acc + curr, 0);

  let modulo = sum % 10;

  return modulo === 0;
};


let invalidCardsStorage = [];

const findInvalidCards = (nestedArray) => {
  const invalidCards = [];
  for (let i = 0; i < nestedArray.length; i++) {
    const currentCard = nestedArray[i];
    if (!validateCred(currentCard)) {
      invalidCards.push(currentCard);
      invalidCardsStorage.push(invalidCards);
    }
  }
  
  return invalidCards;
};

findInvalidCards(batch);

const idInvalidCardCompanies = (nestedArray) =>{
  const companies = [];
  for (let i = 0; i < nestedArray.length; i++) {
    
    const currentCard = nestedArray[i];

    if (currentCard[i][0] === 3) {
      companies.push('Amex');
    }
    else if (currentCard[i][0] === 4) {
      companies.push('Visa');
    }
    else if (currentCard[i][0] === 5) {
      companies.push('Mastercard');
    }
    else if (currentCard[i][0] === 6) {
      companies.push('Discover');
    }
  }
  let uniqueCompanies = [...new Set(companies)];
  return uniqueCompanies;
  //console.log(companies)
}  

console.log(idInvalidCardCompanies(invalidCardsStorage));