(function () {

     function Test() {
    let btn = document.querySelector("button");

    btn.addEventListener("click", () => {
        let year = Number(document.getElementById("year").value);
        let month = document.getElementById("month").value;
        let day = Number(document.getElementById("day").value);

        let outputDiv = document.getElementById("output");
        let p = document.createElement("p");


        function isYearLeapAndValid(year) {
            return ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
        }

        function isMonthValid(month) {
            let months = ["January", "February", "March", "Aprim", "May", "June", "July", "August", "September", "October", "November", "December"];
            return (months.includes(month.toString()));
        }

        function isDayValid(day) {
            return day > 0 && day < 32;
        }

        function daysInMonth(m, y) { // m is 0 indexed: 0-11
            switch (m) {
                case "February":
                    return (y % 4 == 0 && y % 100) || y % 400 == 0 ? 29 : 28;
                case "September": case "April": case "July": case "10":
                    return 30;
                default:
                    return 31
            }
        }


        function isInputValid(year, month, day) {


            if (isMonthValid(month) == true && isDayValid(day) == true) {
                if (daysInMonth(month, year) > 0 && daysInMonth(month, year) >= day) {
                    return true;
                }
            } else {
                return false
            }

        }

        function format(d) {
            let x = new String(d);
            if (x.length < 2) {
                return d = "0" + d
            }
            return d;
        }

        function getIndexOfMonth(month) {
            let months = ["January", "February", "March", "Aprim", "May", "June", "July", "August", "September", "October", "November", "December"].indexOf(month);
            return months;
        }

        day = format(day);

        if (isInputValid(year, month, day)) {
            month = getIndexOfMonth(month);
            month = format(month);

            p.innerText = `Date: ${year}-${month}-${day} is valid`;
        } else {
            p.innerHTML = `Date: ${year}-${month}-${day} is not valid`;
        }
        document.getElementById("year").value="";
        document.getElementById("month").value="";
        document.getElementById("day").value="";

        outputDiv.appendChild(p);
    });
    }
    return function () {
        Test();
    }
})();