MakeDay.js

'use strict';

var GetIntrinsic = require('../GetIntrinsic');

var $floor = GetIntrinsic('%Math.floor%');
var $DateUTC = GetIntrinsic('%Date.UTC%');

var mod = require('../helpers/mod');
var $isFinite = require('../helpers/isFinite');

var DateFromTime = require('./DateFromTime');
var Day = require('./Day');
var MonthFromTime = require('./MonthFromTime');
var ToInteger = require('./ToInteger');
var YearFromTime = require('./YearFromTime');

// https://ecma-international.org/ecma-262/5.1/#sec-15.9.1.12

module.exports = function MakeDay(year, month, date) {
	if (!$isFinite(year) || !$isFinite(month) || !$isFinite(date)) {
		return NaN;
	}
	var y = ToInteger(year);
	var m = ToInteger(month);
	var dt = ToInteger(date);
	var ym = y + $floor(m / 12);
	var mn = mod(m, 12);
	var t = $DateUTC(ym, mn, 1);
	if (YearFromTime(t) !== ym || MonthFromTime(t) !== mn || DateFromTime(t) !== 1) {
		return NaN;
	}
	return Day(t) + dt - 1;
};