text: import toDate from '../toDate/index.js'
  import toInteger from '../_lib/toInteger/index.js'
  import requiredArgs from '../_lib/requiredArgs/index.js'
  
  /**
   * @name startOfWeek
   * @category Week Helpers
   * @summary Return the start of a week for the given date.
   *
   * @description
   * Return the start of a week for the given date.
   * The result will be in the local timezone.
   *
   * ### v2.0.0 breaking changes:
   *
   * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
   *
   * @param {Date|Number} date - the original date
   * @param {Object} [options] - an object with options.
   * @param {Locale} [options.locale=defaultLocale] - the locale object. See [Locale]{@link https://date-fns.org/docs/Locale}
   * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
   * @returns {Date} the start of a week
   * @throws {TypeError} 1 argument required
   * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
   *
   * @example
   * // The start of a week for 2 September 2014 11:55:00:
   * var result = startOfWeek(new Date(2014, 8, 2, 11, 55, 0))
   * //=> Sun Aug 31 2014 00:00:00
   *
   * @example
   * // If the week starts on Monday, the start of the week for 2 September 2014 11:55:00:
   * var result = startOfWeek(new Date(2014, 8, 2, 11, 55, 0), { weekStartsOn: 1 })
   * //=> Mon Sep 01 2014 00:00:00
   */
  export default function startOfWeek(dirtyDate, dirtyOptions) {
    requiredArgs(1, arguments)
  
    var options = dirtyOptions || {}
    var locale = options.locale
    var localeWeekStartsOn =
      locale && locale.options && locale.options.weekStartsOn
    var defaultWeekStartsOn =
      localeWeekStartsOn == null ? 0 : toInteger(localeWeekStartsOn)
    var weekStartsOn =
      options.weekStartsOn == null
        ? defaultWeekStartsOn
        : toInteger(options.weekStartsOn)
  
    // Test if weekStartsOn is between 0 and 6 _and_ is not NaN
    if (!(weekStartsOn >= 0 && weekStartsOn <= 6)) {
      throw new RangeError('weekStartsOn must be between 0 and 6 inclusively')
    }
  
    var date = toDate(dirtyDate)
    var day = date.getDay()
    var diff = (day < weekStartsOn ? 7 : 0) + day - weekStartsOn
  
    date.setDate(date.getDate() - diff)
    date.setHours(0, 0, 0, 0)
    return date
  }
  