import differenceInMilliseconds from '../differenceInMilliseconds/index.js'

var MILLISECONDS_IN_HOUR = 3600000

/**
 * @name differenceInHours
 * @category Hour Helpers
 * @summary Get the number of hours between the given dates.
 *
 * @description
 * Get the number of hours 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}
 * @returns {Number} the number of hours
 * @throws {TypeError} 2 arguments required
 * @throws {RangeError} `options.additionalDigits` must be 0, 1 or 2
 *
 * @example
 * // How many hours are between 2 July 2014 06:50:00 and 2 July 2014 19:00:00?
 * var result = differenceInHours(
 *   new Date(2014, 6, 2, 19, 0),
 *   new Date(2014, 6, 2, 6, 50)
 * )
 * //=> 12
 */
export default function differenceInHours (dirtyDateLeft, dirtyDateRight, dirtyOptions) {
  if (arguments.length < 2) {
    throw new TypeError('2 arguments required, but only ' + arguments.length + ' present')
  }

  var diff = differenceInMilliseconds(dirtyDateLeft, dirtyDateRight, dirtyOptions) / MILLISECONDS_IN_HOUR
  return diff > 0 ? Math.floor(diff) : Math.ceil(diff)
}
