import { constructFrom } from "./constructFrom.js";
import { isSaturday } from "./isSaturday.js";
import { isSunday } from "./isSunday.js";
import { isWeekend } from "./isWeekend.js";
import { toDate } from "./toDate.js";
/**
* The {@link addBusinessDays} function options.
*/
/**
* @name addBusinessDays
* @category Day Helpers
* @summary Add the specified number of business days (mon - fri) to the given date.
*
* @description
* Add the specified number of business days (mon - fri) to the given date, ignoring weekends.
*
* @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
* @typeParam ResultDate - The result `Date` type, it is the type returned from the context function if it is passed, or inferred from the arguments.
*
* @param date - The date to be changed
* @param amount - The amount of business days to be added.
* @param options - An object with options
*
* @returns The new date with the business days added
*
* @example
* // Add 10 business days to 1 September 2014:
* const result = addBusinessDays(new Date(2014, 8, 1), 10)
* //=> Mon Sep 15 2014 00:00:00 (skipped weekend days)
*/
export function addBusinessDays(date, amount, options) {
const _date = toDate(date, options?.in);
const startedOnWeekend = isWeekend(_date, options);
if (isNaN(amount)) return constructFrom(options?.in, NaN);
const hours = _date.getHours();
const sign = amount < 0 ? -1 : 1;
const fullWeeks = Math.trunc(amount / 5);
_date.setDate(_date.getDate() + fullWeeks * 7);
// Get remaining days not part of a full week
let restDays = Math.abs(amount % 5);
// Loops over remaining days
while (restDays > 0) {
_date.setDate(_date.getDate() + sign);
if (!isWeekend(_date, options)) restDays -= 1;
}
// If the date is a weekend day and we reduce a dividable of
// 5 from it, we land on a weekend date.
// To counter this, we add days accordingly to land on the next business day
if (startedOnWeekend && isWeekend(_date, options) && amount !== 0) {
// If we're reducing days, we want to add days until we land on a weekday
// If we're adding days we want to reduce days until we land on a weekday
if (isSaturday(_date, options))
_date.setDate(_date.getDate() + (sign < 0 ? 2 : -1));
if (isSunday(_date, options))
_date.setDate(_date.getDate() + (sign < 0 ? 1 : -2));
}
// Restore hours to avoid DST lag
_date.setHours(hours);
return _date;
}
// Fallback for modularized imports:
export default addBusinessDays;