@potchangelo/money-to-thai-word/src/moneyToThaiWord.js

Convert money in currency Baht and Satang to Thai word (Thai or English locale).

const { getBahtAndSatang } = require('./shared');

/**
 * Convert base 10, 100, 1000, 10000, 100000 to word.
 * @param {10|100|1000|10000|100000} base Number in 10, 100, ..., 100000.
 */
function baseToWord(base) {
  if (base === 1e5) return 'แสน';
  if (base === 1e4) return 'หมื่น';
  if (base === 1e3) return 'พัน';
  if (base === 1e2) return 'ร้อย';
  if (base === 1e1) return 'สิบ';
  return '';
}

/**
 * Convert front number and its base number to word.
 * @param {number} front Integer number between 1-9.
 * @param {1|10|100|1000|10000|100000} base Number in 1, 10, ..., 100000.
 * @param {boolean} [hasTen=false] Is x (this front number) behind ten-order number like 1x, 2x
 * @example
 * frontAndBaseToWord(2, 10)
 * // "ยี่" + "สิบ"
 * @example
 * frontAndBaseToWord(7, 100)
 * // "เจ็ด" + "ร้อย"
 * @example
 * frontAndBaseToWord(5)
 * // "ห้า"
 */
function frontAndBaseToWord(front, base, hasTen = false) {
  let frontWord = '';
  if (base === 1e1 && front === 2) {
    frontWord = 'ยี่';
  } else if (base === 1e1 && front === 1) {
    frontWord = '';
  } else if (base === 1 && front === 1 && hasTen) {
    frontWord = 'เอ็ด';
  } else {
    if (front === 9) frontWord = 'เก้า';
    if (front === 8) frontWord = 'แปด';
    if (front === 7) frontWord = 'เจ็ด';
    if (front === 6) frontWord = 'หก';
    if (front === 5) frontWord = 'ห้า';
    if (front === 4) frontWord = 'สี่';
    if (front === 3) frontWord = 'สาม';
    if (front === 2) frontWord = 'สอง';
    if (front === 1) frontWord = 'หนึ่ง';
  }
  return frontWord + baseToWord(base);
}

/**
 * Convert number (1-999999) to word.
 * @param {number} n Integer number between 1-999999.
 * @example
 * numberToWord(357)
 * // "สามร้อยห้าสิบเจ็ด"
 * @example
 * numberToWord(51215)
 * // "ห้าหมื่นหนึ่งพันสองร้อยสิบห้า"
 */
function numberToWord(n) {
  if (n < 1 || n > 999999) return '';

  let word = '';
  let nClone = n;
  let hasTen = false;
  for (let j = `${n}`.length - 1; j >= 0; j--) {
    const base = 10 ** j;
    const dividedMoney = nClone / base;
    if (dividedMoney >= 1) {
      const front = Math.floor(dividedMoney);
      const moneyWord = frontAndBaseToWord(front, base, hasTen);
      word += moneyWord;
      nClone %= base;
      hasTen = base === 1e1;
    }
  }
  return word;
}

/**
 * Convert baht to ordered sub-bahts (Array of numbers between 0-999999).
 * @param {number} baht Integer baht value.
 * @example
 * bahtToSubBahts(10200300)
 * // [10, 200300]
 */
function bahtToSubBahts(baht) {
  // Empty array for zero baht
  if (baht === 0) return [];

  // Slice baht string to sub-bahts (6 digits) array
  const bahtString = `${baht}`;
  const subBahts = [];
  const subBathsCount = Math.ceil(bahtString.length / 6);
  for (let i = 1; i <= Math.min(subBathsCount, 6); i++) {
    let subBaht = '';
    if (i === 1) {
      subBaht = bahtString.slice(-6 * i);
    } else {
      subBaht = bahtString.slice(-6 * i, -6 * (i - 1));
    }
    if (subBaht === '') break;
    subBahts.unshift(+subBaht);
  }
  return subBahts;
}

/**
 * Convert sub-bahts to word.
 * @param {number[]} subBahts Array of integer numbers between 0-999999.
 * @example
 * subBahtToWord([10, 200300])
 * // "สิบล้าน" + "สอนแสนสามร้อย" + "บาท"
 */
function subBahtToWord(subBahts) {
  // Empty string for zero baht
  if (subBahts.length === 0) return '';

  // Convert each ordered sub-bahts to word
  const word = subBahts.reduce((prevWord, subBaht, index) => {
    let currentWord = numberToWord(subBaht);
    if (index !== subBahts.length - 1) {
      currentWord += 'ล้าน';
    }
    return prevWord + currentWord;
  }, '');
  return word + 'บาท';
}

/**
 * Convert satang to word.
 * @param {number} satang Integer satang value between 1-99.
 * @example
 * satangToWord(75);
 * // "เจ็ดสิบห้า" + "สตางค์"
 */
function satangToWord(satang) {
  return satang > 0 ? numberToWord(satang) + 'สตางค์' : '';
}

/**
 * @typedef {object} ThaiWordOptions
 * @property {boolean} showActual
 */

/**
 * @type ThaiWordOptions
 */
const defaultOptions = {
  showActual: true,
};

/**
 * Convert money (number) to Thai word (string).
 * @param {number} money Input money.
 * @param {ThaiWordOptions} [options] Optional configurations.
 */
function moneyToThaiWord(money, options = {}) {
  let { showActual } = { ...defaultOptions, ...options };

  // Lt. zero or mte. quintillion cases
  if (money < 0 || money >= 1e18) return '';

  let { baht, satang } = getBahtAndSatang(money);

  // Zero case
  if (baht === 0 && satang === 0) return `ศูนย์บาท${showActual ? 'ถ้วน' : ''}`;

  // Build baht and satang word
  let word = subBahtToWord(bahtToSubBahts(baht));
  word += satangToWord(satang);
  word += satang === 0 && showActual ? 'ถ้วน' : '';

  return word;
}

module.exports = moneyToThaiWord;