'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = differenceInCalendarWeeks;

var _index = require('../_lib/getTimezoneOffsetInMilliseconds/index.js');

var _index2 = _interopRequireDefault(_index);

var _index3 = require('../startOfWeek/index.js');

var _index4 = _interopRequireDefault(_index3);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

var MILLISECONDS_IN_WEEK = 604800000;

/**
 * @name differenceInCalendarWeeks
 * @category Week Helpers
 * @summary Get the number of calendar weeks between the given dates.
 *
 * @description
 * Get the number of calendar weeks between the given dates.
 *
 *
 * ### 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|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}
 * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
 * @param {Locale} [options.locale=defaultLocale] - the locale object. See [Locale]{@link https://date-fns.org/docs/Locale}
 * @returns {Number} the number of calendar weeks
 * @throws {TypeError} 2 arguments required
 * @throws {RangeError} `options.additionalDigits` must be 0, 1 or 2
 * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
 *
 * @example
 * // How many calendar weeks are between 5 July 2014 and 20 July 2014?
 * var result = differenceInCalendarWeeks(
 *   new Date(2014, 6, 20),
 *   new Date(2014, 6, 5)
 * )
 * //=> 3
 *
 * @example
 * // If the week starts on Monday,
 * // how many calendar weeks are between 5 July 2014 and 20 July 2014?
 * var result = differenceInCalendarWeeks(
 *   new Date(2014, 6, 20),
 *   new Date(2014, 6, 5),
 *   { weekStartsOn: 1 }
 * )
 * //=> 2
 */
function differenceInCalendarWeeks(dirtyDateLeft, dirtyDateRight, dirtyOptions) {
  if (arguments.length < 2) {
    throw new TypeError('2 arguments required, but only ' + arguments.length + ' present');
  }

  var startOfWeekLeft = (0, _index4.default)(dirtyDateLeft, dirtyOptions);
  var startOfWeekRight = (0, _index4.default)(dirtyDateRight, dirtyOptions);

  var timestampLeft = startOfWeekLeft.getTime() - (0, _index2.default)(startOfWeekLeft);
  var timestampRight = startOfWeekRight.getTime() - (0, _index2.default)(startOfWeekRight);

  // 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);
}
module.exports = exports['default'];