/**
 * TIN (Anguilla Tax Identification Number).
 *
 * The Anguilla Tax Identification Number is issued to individuals and entities
 * for tax purposes. The number consists of 10 digits in the format XXXXX-XXXXX
 * where the first 5 digits represent the taxpayer's registration number and
 * the last 5 digits are a sequence number (including prefix and check digit).
 *
 * TINs are unique numbers automatically generated by the tax administration system
 * and consist of 10 digits, including prefix digit and check digit.
 *   - Individual TINs start with prefix 1
 *   - Non-Individual (business) TINs start with prefix 2
 *
 * Source
 *   https://www.oecd.org/tax/automatic-exchange/crs-implementation-and-assistance/tax-identification-numbers/Anguilla-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, ' -');
}

const impl: Validator = {
  name: 'Anguilla Tax Identification Number',
  localName: 'Tax Identification Number',
  abbreviation: 'TIN',

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

    if (err) {
      throw err;
    }

    return value;
  },

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

    if (value.length !== 10) {
      return value;
    }

    return `${value.substring(0, 5)}-${value.substring(5)}`;
  },

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

    if (error) {
      return { isValid: false, error };
    }

    if (value.length !== 10) {
      return { isValid: false, error: new exceptions.InvalidLength() };
    }

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

    const prefix = value[0];

    if (prefix !== '1' && prefix !== '2') {
      return { isValid: false, error: new exceptions.InvalidComponent() };
    }

    // Validate checksum
    //     const [front, check] = strings.splitAt(value, 8);
    //     const sum = weightedSum(front, {
    //       weights: [7, 3, 1, 7, 3, 1, 7, 3],
    //       modulus: 10,
    //     });

    //     if (String(sum) !== check) {
    //       return { isValid: false, error: new exceptions.InvalidChecksum() };
    //     }

    return {
      isValid: true,
      compact: value,
      isIndividual: prefix === '1',
      isCompany: prefix === '2',
    };
  },
};

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