import { toDate } from "./toDate.mjs";

/**
 * The locale string (see: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl#locales_argument).
 */

/**
 * The format options (see: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat#options)
 */

/**
 * The locale options.
 */

/**
 * @name intlFormat
 * @category Common Helpers
 * @summary Format the date with Intl.DateTimeFormat (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat).
 *
 * @description
 * Return the formatted date string in the given format.
 * The method uses [`Intl.DateTimeFormat`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat) inside.
 * formatOptions are the same as [`Intl.DateTimeFormat` options](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat#using_options)
 *
 * > ⚠️ Please note that before Node version 13.0.0, only the locale data for en-US is available by default.
 *
 * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
 *
 * @param date - The date to format
 *
 * @returns The formatted date string
 *
 * @throws `date` must not be Invalid Date
 *
 * @example
 * // Represent 4 October 2019 in middle-endian format:
 * const result = intlFormat(new Date(2019, 9, 4, 12, 30, 13, 456))
 * //=> 10/4/2019
 */

/**
 * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
 *
 * @param date - The date to format
 * @param localeOptions - An object with locale
 *
 * @returns The formatted date string
 *
 * @throws `date` must not be Invalid Date
 *
 * @example
 * // Represent 4 October 2019 in Korean.
 * // Convert the date with locale's options.
 * const result = intlFormat(new Date(2019, 9, 4, 12, 30, 13, 456), {
 *   locale: 'ko-KR',
 * })
 * //=> 2019. 10. 4.
 */

/**
 * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
 *
 * @param date - The date to format
 * @param formatOptions - The format options
 *
 * @returns The formatted date string
 *
 * @throws `date` must not be Invalid Date
 *
 * @example
 * // Represent 4 October 2019.
 * // Convert the date with format's options.
 * const result = intlFormat.default(new Date(2019, 9, 4, 12, 30, 13, 456), {
 *   year: 'numeric',
 *   month: 'numeric',
 *   day: 'numeric',
 *   hour: 'numeric',
 * })
 * //=> 10/4/2019, 12 PM
 */

/**
 * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
 *
 * @param date - The date to format
 * @param formatOptions - The format options
 * @param localeOptions - An object with locale
 *
 * @returns The formatted date string
 *
 * @throws `date` must not be Invalid Date
 *
 * @example
 * // Represent 4 October 2019 in German.
 * // Convert the date with format's options and locale's options.
 * const result = intlFormat(new Date(2019, 9, 4, 12, 30, 13, 456), {
 *   weekday: 'long',
 *   year: 'numeric',
 *   month: 'long',
 *   day: 'numeric',
 * }, {
 *   locale: 'de-DE',
 * })
 * //=> Freitag, 4. Oktober 2019
 */

export function intlFormat(date, formatOrLocale, localeOptions) {
  let formatOptions;

  if (isFormatOptions(formatOrLocale)) {
    formatOptions = formatOrLocale;
  } else {
    localeOptions = formatOrLocale;
  }

  return new Intl.DateTimeFormat(localeOptions?.locale, formatOptions).format(
    toDate(date),
  );
}

function isFormatOptions(opts) {
  return opts !== undefined && !("locale" in opts);
}

// Fallback for modularized imports:
export default intlFormat;