'use strict';

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

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

var _index2 = _interopRequireDefault(_index);

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

var MILLISECONDS_IN_DAY = 24 * 60 * 60 * 1000;

/**
 * @name getOverlappingDaysInIntervals
 * @category Interval Helpers
 * @summary Get the number of days that overlap in two time intervals
 *
 * @description
 * Get the number of days that overlap in two time intervals
 *
 *
 * ### 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).
 *
 * - The function was renamed from `getOverlappingDaysInRanges` to `getOverlappingDaysInIntervals`.
 *   This change was made to mirror the use of the word "interval" in standard ISO 8601:2004 terminology:
 *
 *   ```
 *   2.1.3
 *   time interval
 *   part of the time axis limited by two instants
 *   ```
 *
 *   Also, this function now accepts an object with `start` and `end` properties
 *   instead of two arguments as an interval.
 *   This function now throws `RangeError` if the start of the interval is after its end
 *   or if any date in the interval is `Invalid Date`.
 *
 *   ```javascript
 *   // Before v2.0.0
 *
 *   getOverlappingDaysInRanges(
 *     new Date(2014, 0, 10), new Date(2014, 0, 20),
 *     new Date(2014, 0, 17), new Date(2014, 0, 21)
 *   )
 *
 *   // v2.0.0 onward
 *
 *   getOverlappingDaysInIntervals(
 *     { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
 *     { start: new Date(2014, 0, 17), end: new Date(2014, 0, 21) }
 *   )
 *   ```
 *
 * @param {Interval} intervalLeft - the first interval to compare. See [Interval]{@link docs/Interval}
 * @param {Interval} intervalRight - the second interval to compare. See [Interval]{@link docs/Interval}
 * @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 days that overlap in two time intervals
 * @throws {TypeError} 2 arguments required
 * @throws {RangeError} `options.additionalDigits` must be 0, 1 or 2
 * @throws {RangeError} The start of an interval cannot be after its end
 * @throws {RangeError} Date in interval cannot be `Invalid Date`
 *
 * @example
 * // For overlapping time intervals adds 1 for each started overlapping day:
 * getOverlappingDaysInIntervals(
 *   { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
 *   { start: new Date(2014, 0, 17), end: new Date(2014, 0, 21) }
 * )
 * //=> 3
 *
 * @example
 * // For non-overlapping time intervals returns 0:
 * getOverlappingDaysInIntervals(
 *   { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
 *   { start: new Date(2014, 0, 21), end: new Date(2014, 0, 22) }
 * )
 * //=> 0
 */
function getOverlappingDaysInIntervals(dirtyIntervalLeft, dirtyIntervalRight, dirtyOptions) {
  if (arguments.length < 2) {
    throw new TypeError('2 arguments required, but only ' + arguments.length + ' present');
  }

  var intervalLeft = dirtyIntervalLeft || {};
  var intervalRight = dirtyIntervalRight || {};
  var leftStartTime = (0, _index2.default)(intervalLeft.start, dirtyOptions).getTime();
  var leftEndTime = (0, _index2.default)(intervalLeft.end, dirtyOptions).getTime();
  var rightStartTime = (0, _index2.default)(intervalRight.start, dirtyOptions).getTime();
  var rightEndTime = (0, _index2.default)(intervalRight.end, dirtyOptions).getTime();

  // Throw an exception if start date is after end date or if any date is `Invalid Date`
  if (!(leftStartTime <= leftEndTime && rightStartTime <= rightEndTime)) {
    throw new RangeError('Invalid interval');
  }

  var isOverlapping = leftStartTime < rightEndTime && rightStartTime < leftEndTime;

  if (!isOverlapping) {
    return 0;
  }

  var overlapStartDate = rightStartTime < leftStartTime ? leftStartTime : rightStartTime;

  var overlapEndDate = rightEndTime > leftEndTime ? leftEndTime : rightEndTime;

  var differenceInMs = overlapEndDate - overlapStartDate;

  return Math.ceil(differenceInMs / MILLISECONDS_IN_DAY);
}
module.exports = exports['default'];