se-panfilov/jsvat

import { Country, Rules } from '../jsvat';

export const russia: Country = {
  name: 'Russian Federation',
  codes: ['RU', 'RUS', '643'],
  calcFn: (vat: string): boolean => {
    // See http://russianpartner.biz/test_inn.html for algorithm
    return _check10DigitINN(vat, russia.rules) || _check12DigitINN(vat, russia.rules);
  },
  rules: {
    multipliers: {
      m_1: [2, 4, 10, 3, 5, 9, 4, 6, 8, 0],
      m_2: [7, 2, 4, 10, 3, 5, 9, 4, 6, 8, 0],
      m_3: [3, 7, 2, 4, 10, 3, 5, 9, 4, 6, 8, 0]
    },
    regex: [/^(RU)(\d{10}|\d{12})$/]
  }
};

function _check10DigitINN(vat: string, rules: Rules): boolean {
  let total = 0;

  if (vat.length === 10) {
    for (let i = 0; i < 10; i++) {
      total += Number(vat.charAt(i)) * rules.multipliers.m_1[i];
    }

    total = total % 11;
    if (total > 9) {
      total = total % 10;
    }

    // Compare it with the last character of the VAT number. If it is the same, then it's valid
    const expect = Number(vat.slice(9, 10));
    return total === expect;
  }

  return false;
}

function _check12DigitINN(vat: string, rules: Rules): boolean {
  let total1 = 0;
  let total2 = 0;

  if (vat.length === 12) {
    for (let j = 0; j < 11; j++) {
      total1 += Number(vat.charAt(j)) * rules.multipliers.m_2[j];
    }

    total1 = total1 % 11;

    if (total1 > 9) {
      total1 = total1 % 10;
    }

    for (let k = 0; k < 11; k++) {
      total2 += Number(vat.charAt(k)) * rules.multipliers.m_3[k];
    }

    total2 = total2 % 11;
    if (total2 > 9) {
      total2 = total2 % 10;
    }

    // Compare the first check with the 11th character and the second check with the 12th and last
    // character of the VAT number. If they're both the same, then it's valid
    const expect = total1 === Number(vat.slice(10, 11));
    const expect2 = total2 === Number(vat.slice(11, 12));
    return expect && expect2;
  }

  return false;
}