var CurrentStyleSheet = 1;
var AvailableStyleSheets = new Array("A-", "A", "A+");

function setActiveStyleSheet(title) {
  	var i, a, main;
  	for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    	if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {
      		a.disabled = true;
      		if (a.getAttribute("title") == title) {
	  			a.disabled = false;
	  		}
    	}
  	}
}

function setBigger(){
	title = getActiveStyleSheet();
	for(i=0; (i <= AvailableStyleSheets.length); i++) {
		if (AvailableStyleSheets[i] == title) {
			CurrentStyleSheet = i;
		}
	}
	
	if ((CurrentStyleSheet + 1) < AvailableStyleSheets.length) {
		setActiveStyleSheet(AvailableStyleSheets[CurrentStyleSheet + 1]);
	}
}

function setSmaller(){
	title = getActiveStyleSheet();
	for(i=0; (i <= AvailableStyleSheets.length); i++) {
		if (AvailableStyleSheets[i] == title) {
			CurrentStyleSheet = i;
		}
	}
	
	if ((CurrentStyleSheet - 1) >= 0) {
		setActiveStyleSheet(AvailableStyleSheets[CurrentStyleSheet - 1]);
	}
}

function getActiveStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && !a.disabled) return a.getAttribute("title");
  }
  return null;
}

function getPreferredStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
   	if(a.getAttribute("rel").indexOf("style") != -1
       && a.getAttribute("rel").indexOf("alt") == -1
       && a.getAttribute("title")
       ) return a.getAttribute("title");
  }
  return "A";
}

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 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;
}

window.onload = function(e) {
  var cookie = readCookie("style");
  var title = cookie ? cookie : getPreferredStyleSheet();
  setActiveStyleSheet(title);
}

window.onunload = function(e) {
  var title = getActiveStyleSheet();
  createCookie("style", title, 365);
}

var cookie = readCookie("style");
var title = cookie ? cookie : getPreferredStyleSheet();
setActiveStyleSheet(title);