import differenceInCalendarWeeks from '../differenceInCalendarWeeks/index.js'
import lastDayOfMonth from '../lastDayOfMonth/index.js'
import startOfMonth from '../startOfMonth/index.js'

/**
 * @name getWeeksInMonth
 * @category Week Helpers
 * @summary Get the number of calendar weeks a month spans.
 *
 * @description
 * Get the number of calendar weeks the month in the given date spans.
 *
 *
 * ### 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} date - the given 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 does February 2015 span?
 * var result = getWeeksInMonth(new Date(2015, 1, 8))
 * //=> 4
 *
 * @example
 * // If the week starts on Monday,
 * // how many calendar weeks does July 2017 span?
 * var result = getWeeksInMonth(new Date(2017, 6, 5), { weekStartsOn: 1 })
 * //=> 6
 */
export default function getWeeksInMonth(dirtyDate, dirtyOptions) {
  if (arguments.length < 1) {
    throw new TypeError(
      '1 argument required, but only ' + arguments.length + ' present'
    )
  }

  return (
    differenceInCalendarWeeks(
      lastDayOfMonth(dirtyDate, dirtyOptions),
      startOfMonth(dirtyDate, dirtyOptions),
      dirtyOptions
    ) + 1
  )
}
