import LocalZone from "./zones/localZone.js";
import IANAZone from "./zones/IANAZone.js";
import Locale from "./impl/locale.js";

import { normalizeZone } from "./impl/zoneUtil.js";

let now = () => Date.now(),
  defaultZone = null, // not setting this directly to LocalZone.instance bc loading order issues
  defaultLocale = null,
  defaultNumberingSystem = null,
  defaultOutputCalendar = null,
  throwOnInvalid = false;

/**
 * Settings contains static getters and setters that control Luxon's overall behavior. Luxon is a simple library with few options, but the ones it does have live here.
 */
export default class Settings {
  /**
   * Get the callback for returning the current timestamp.
   * @type {function}
   */
  static get now() {
    return now;
  }

  /**
   * Set the callback for returning the current timestamp.
   * The function should return a number, which will be interpreted as an Epoch millisecond count
   * @type {function}
   * @example Settings.now = () => Date.now() + 3000 // pretend it is 3 seconds in the future
   * @example Settings.now = () => 0 // always pretend it's Jan 1, 1970 at midnight in UTC time
   */
  static set now(n) {
    now = n;
  }

  /**
   * Get the default time zone to create DateTimes in.
   * @type {string}
   */
  static get defaultZoneName() {
    return Settings.defaultZone.name;
  }

  /**
   * Set the default time zone to create DateTimes in. Does not affect existing instances.
   * @type {string}
   */
  static set defaultZoneName(z) {
    if (!z) {
      defaultZone = null;
    } else {
      defaultZone = normalizeZone(z);
    }
  }

  /**
   * Get the default time zone object to create DateTimes in. Does not affect existing instances.
   * @type {Zone}
   */
  static get defaultZone() {
    return defaultZone || LocalZone.instance;
  }

  /**
   * Get the default locale to create DateTimes with. Does not affect existing instances.
   * @type {string}
   */
  static get defaultLocale() {
    return defaultLocale;
  }

  /**
   * Set the default locale to create DateTimes with. Does not affect existing instances.
   * @type {string}
   */
  static set defaultLocale(locale) {
    defaultLocale = locale;
  }

  /**
   * Get the default numbering system to create DateTimes with. Does not affect existing instances.
   * @type {string}
   */
  static get defaultNumberingSystem() {
    return defaultNumberingSystem;
  }

  /**
   * Set the default numbering system to create DateTimes with. Does not affect existing instances.
   * @type {string}
   */
  static set defaultNumberingSystem(numberingSystem) {
    defaultNumberingSystem = numberingSystem;
  }

  /**
   * Get the default output calendar to create DateTimes with. Does not affect existing instances.
   * @type {string}
   */
  static get defaultOutputCalendar() {
    return defaultOutputCalendar;
  }

  /**
   * Set the default output calendar to create DateTimes with. Does not affect existing instances.
   * @type {string}
   */
  static set defaultOutputCalendar(outputCalendar) {
    defaultOutputCalendar = outputCalendar;
  }

  /**
   * Get whether Luxon will throw when it encounters invalid DateTimes, Durations, or Intervals
   * @type {boolean}
   */
  static get throwOnInvalid() {
    return throwOnInvalid;
  }

  /**
   * Set whether Luxon will throw when it encounters invalid DateTimes, Durations, or Intervals
   * @type {boolean}
   */
  static set throwOnInvalid(t) {
    throwOnInvalid = t;
  }

  /**
   * Reset Luxon's global caches. Should only be necessary in testing scenarios.
   * @return {void}
   */
  static resetCaches() {
    Locale.resetCache();
    IANAZone.resetCache();
  }
}