/**
 * MVA (Merverdiavgift, Norwegian VAT number).
 *
 * The VAT number is the standard Norwegian organisation number
 * (Organisasjonsnummer) with 'MVA' as suffix.
 *
 * Source
 *    https://www.oecd.org/tax/automatic-exchange/crs-implementation-and-assistance/tax-identification-numbers/Norway-TIN.pdf
 *
 * PERSON/ENTITY
 */

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

function clean(input: string): ReturnType<typeof strings.cleanUnicode> {
  return strings.cleanUnicode(input, ' ', 'NO');
}

const impl: Validator = {
  name: 'Norwegian VAT Number',
  localName: 'Merverdiavgift',
  abbreviation: 'MVA',

  compact(input: string): string {
    const [value, err] = clean(input);

    if (err) {
      throw err;
    }

    return value;
  },

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

    return `NO ${strings.splitAt(value, 3, 6, 9).join(' ')}`;
  },

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

    if (error) {
      return { isValid: false, error };
    }
    if (value.length !== 12) {
      return { isValid: false, error: new exceptions.InvalidLength() };
    }
    if (!strings.isdigits(value.substr(0, 9))) {
      return { isValid: false, error: new exceptions.InvalidFormat() };
    }

    const [front, end] = strings.splitAt(value, 9);
    if (end !== 'MVA') {
      return { isValid: false, error: new exceptions.InvalidFormat() };
    }

    const sum = weightedSum(front, {
      weights: [3, 2, 7, 6, 5, 4, 3, 2, 1],
      modulus: 11,
    });

    if (sum !== 0) {
      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;