/**
 *
 * UID (Umsatzsteuer-Identifikationsnummer, Austrian VAT number).
 *
 * The Austrian UID is a 9-digit number that starts with a U (optionally
 * preceded with AT). The last digit is a check digit.
 *
 * Sources:
 *   https://www.ruc.com.py/
 *
 * ENTITY
 */

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

function clean(input: string): ReturnType<typeof strings.cleanUnicode> {
  const [value, err] = strings.cleanUnicode(input, ' -./');

  if (err) {
    return [value, err];
  }
  if (value.startsWith('AT')) {
    return [value.substr(2), null];
  }

  return [value, null];
}

const impl: Validator = {
  name: 'Austrian VAT Number',
  localName: 'Umsatzsteuer-Identifikationsnummer',
  abbreviation: 'UID',

  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 (!value.startsWith('U') || !strings.isdigits(value.substr(1))) {
      return { isValid: false, error: new exceptions.InvalidComponent() };
    }

    const [, front, check] = strings.splitAt(value, 1, 8);

    const digit = String((16 - luhnChecksumValue(front)) % 10);

    if (check !== digit) {
      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;