text: import getTimezoneOffsetInMilliseconds from '../_lib/getTimezoneOffsetInMilliseconds/index.js'
  import startOfISOWeek from '../startOfISOWeek/index.js'
  
  var MILLISECONDS_IN_WEEK = 604800000
  
  /**
   * @name differenceInCalendarISOWeeks
   * @category ISO Week Helpers
   * @summary Get the number of calendar ISO weeks between the given dates.
   *
   * @description
   * Get the number of calendar ISO weeks between the given dates.
   *
   * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
   *
   * @param {Date|String|Number} dateLeft - the later date
   * @param {Date|String|Number} dateRight - the earlier date
   * @param {Options} [options] - the object with options. See [Options]{@link https://date-fns.org/docs/Options}
   * @param {0|1|2} [options.additionalDigits=2] - passed to `toDate`. See [toDate]{@link https://date-fns.org/docs/toDate}
   * @returns {Number} the number of calendar ISO weeks
   * @throws {TypeError} 2 arguments required
   * @throws {RangeError} `options.additionalDigits` must be 0, 1 or 2
   *
   * @example
   * // How many calendar ISO weeks are between 6 July 2014 and 21 July 2014?
   * var result = differenceInCalendarISOWeeks(
   *   new Date(2014, 6, 21),
   *   new Date(2014, 6, 6)
   * )
   * //=> 3
   */
  export default function differenceInCalendarISOWeeks (dirtyDateLeft, dirtyDateRight, dirtyOptions) {
    if (arguments.length < 2) {
      throw new TypeError('2 arguments required, but only ' + arguments.length + ' present')
    }
  
    var startOfISOWeekLeft = startOfISOWeek(dirtyDateLeft, dirtyOptions)
    var startOfISOWeekRight = startOfISOWeek(dirtyDateRight, dirtyOptions)
  
    var timestampLeft = startOfISOWeekLeft.getTime() -
      getTimezoneOffsetInMilliseconds(startOfISOWeekLeft)
    var timestampRight = startOfISOWeekRight.getTime() -
      getTimezoneOffsetInMilliseconds(startOfISOWeekRight)
  
    // Round the number of days to the nearest integer
    // because the number of milliseconds in a week is not constant
    // (e.g. it's different in the week of the daylight saving time clock shift)
    return Math.round((timestampLeft - timestampRight) / MILLISECONDS_IN_WEEK)
  }
  