( function() {
    'use strict';

    if ( 'getElementById' in document && 'addEventListener' in window ) {

    //Create the cookie object
    const cookieStorage = {
        setCookie: function setCookie(key, value, time, path) {
            var expires = new Date();
            expires.setTime(expires.getTime() + time);
            var pathValue = '';
            if (typeof path !== 'undefined') {
                pathValue = 'path=' + path + ';';
            }
            document.cookie = key + '=' + value + ';' + pathValue + 'expires=' + expires.toUTCString();
        },
        getCookie: function getCookie(key) {
            var keyValue = document.cookie.match('(^|;) ?' + key + '=([^;]*)(;|$)');
            return keyValue ? keyValue[2] : null;
        },
        removeCookie: function removeCookie(key) {
            document.cookie = key + '=; Max-Age=0; path=/';
        }
    };

    //Click on dark mode icon. Add dark mode classes and wrappers. Store user preference through sessions

    const swichi = document.getElementById( 'switch' );
    const bode = document.getElementById( 'site-body' );
    swichi.addEventListener( 'click', ()=> {
        //show either moon or sun
        swichi.classList.toggle( 'activu' );
        //if dark mode is selected
        if ( swichi.classList.contains( 'activu' ) ) {
            //add dark mode into body 
            bode.classList.add( 'dark-mode' );
            cookieStorage.setCookie('tsNightMode', 'true', 2628000000, '/');
        } else {
            bode.classList.remove( 'dark-mode' );
            setTimeout( ()=> {
                cookieStorage.removeCookie('tsNightMode');
            }, 100);
        }
    });

    swichi.addEventListener( 'keypress', (evt) => {
        if ( evt.key === 'Enter' ) {
            evt.preventDefault();
            bode.classList.add( 'dark-mode');
        }
    });

    //Check Storage. Display user preference 
    if (cookieStorage.getCookie('tsNightMode')) {
        bode.classList.add( 'dark-mode' );
        swichi.classList.add( 'activu' );
    }
}
}) ();