stdnum/src/de/vat.ts

Standard Number Validation

/**
 * Ust ID Nr. (Umsatzsteuer Identifikationsnummer, German VAT number).
 *
 * The number is 9 digits long and uses the ISO 7064 Mod 11, 10 check digit
 * algorithm.
 *
 * ENTITY
 */

import * as exceptions from '../exceptions';
import { strings } from '../util';
import { Validator, ValidateReturn } from '../types';
import { iso7064mod10x11validate } from '../util/iso7064';

function clean(input: string): ReturnType<typeof strings.cleanUnicode> {
  const [value, err] = strings.cleanUnicode(input, ' -./,');
  if (err !== null) {
    return [value, err];
  }
  if (value.startsWith('DE')) {
    return [value.substr(2), null];
  }

  return [value, null];
}

const impl: Validator = {
  name: 'German VAT Number',
  localName: 'Umsatzsteuer Identifikationsnummer',
  abbreviation: 'USt ID Nr.',
  compact(input: string): string {
    const [value, err] = clean(input);

    if (err) {
      throw err;
    }

    return value;
  },

  format(input: string): string {
    const [value] = clean(input);

    return value;
  },

  validate(input: string): ValidateReturn {
    const [value, error] = clean(input);

    if (error) {
      return { isValid: false, error };
    }
    if (value.length !== 9) {
      return { isValid: false, error: new exceptions.InvalidLength() };
    }
    if (!strings.isdigits(value)) {
      return { isValid: false, error: new exceptions.InvalidFormat() };
    }

    if (!iso7064mod10x11validate(value)) {
      return { isValid: false, error: new exceptions.InvalidChecksum() };
    }

    return {
      isValid: true,
      compact: value,
      isIndividual: false,
      isCompany: true,
    };
  },
};

export const { name, localName, abbreviation, validate, format, compact } =
  impl;