var cookie_name = "style";

function switchMode() {
	cookie = readCookie();
	mode = (cookie == null) ? "night" : cookie;
	
	//switch mode
	mode = (mode == "night") ? "day" : "night";
	setCookie(mode);
	
	setStyle(mode);
	//window.location.reload();
}

function setStyle(mode) {
	if (mode == "night") {
		document.getElementById('css_link').href = "./conf/css_night.css";
		document.getElementById('mode_link').innerHTML = "[day mode]";
	} else {
		document.getElementById('css_link').href = "./conf/css_day.css";
		document.getElementById('mode_link').innerHTML = "[night mode]";
	}
}

function setCookie(cookie_value) {
	var days = 30;

	var date = new Date();
	date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
	var expires = "; expires=" + date.toGMTString();
	document.cookie = cookie_name + "=" + cookie_value + expires + "; path=/";
}

function readCookie() {
	var nameEQ = cookie_name + "=";
	var ca = document.cookie.split(';');
	for (var i=0; i < ca.length; i++) {
		var c = ca[i];
		while (c.charAt(0) == ' ') {
			c = c.substring(1, c.length);
		}
		if (c.indexOf(nameEQ) == 0) {
			return c.substring(nameEQ.length, c.length);
		}
	}
	return null;
}