function createCookie(name,value,days) {
	if (days) {
		var date = new Date();
		date.setTime(date.getTime()+(days*24*60*60*1000));
		var expires = "; expires="+date.toGMTString();
	}
	else var expires = "";
	document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
	var nameEQ = 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;
}

function eraseCookie(name) {
	createCookie(name,"",-1);
}

function changeBg(imgnum) {
	var placeholder = document.getElementById("placeholder");
	var plimg = document.createElement("img");
	plimg.src = "imgs/homepage/img-" + imgnum + ".jpg";
	placeholder.appendChild(plimg);
	imgnum++;
	if (imgnum > 5) imgnum = 1;
	createCookie('waimg', imgnum);
}

function defaultBg() {
	var imgnum = readCookie('waimg');
	if (!imgnum) {
		createCookie('waimg', 1);
		changeBg(1);
	}
	else
		changeBg(imgnum);
}

addLoadEvent (defaultBg);