/**************************************************************************/
// stylesheets go here
// first one is the default
// href is <style_path><stylesheet><ext>
var stylesheets = Array(
	"default",
	"purple",
	"no"
);
var ext = ".css";

/**************************************************************************/
/* find the first <link rel="stylesheet" type="text/css" ... > */
function getFirstStyleSheetLink() {
	// for each link
	for(i=0; (link = document.getElementsByTagName("link")[i]); i++) {
		// if link is stylesheet and is not alternative
		if(link.getAttribute("rel").indexOf("style") != -1 && 
		   link.getAttribute("rel").indexOf("alt") == -1)
			return link;
	}
	return null;
}

/* given a <link> tag  and an stylesheet index, set the tag properties */
function setLinkTagProperties(tag, styleSheetIndex) {

	tag.setAttribute("title", stylesheets[styleSheetIndex]);
	tag.setAttribute("href", style_path + stylesheets[i] + ext);
	
	tag.disabled = false;
}

/* set active stylesheet */
function setActiveStyleSheet(title) {

	// find <link> tag 
   	link = getFirstStyleSheetLink();
	if (!link) return;
	
	
	// for each stylesheet
	for(i=0; i < stylesheets.length; i++) {
		  // if stylesheet matches the title we want to set
	      if(stylesheets[i] == title) { 
				// set <link> tag attributes
				setLinkTagProperties(link, i);
				return;
		  }
	}
	//  couldn't find so use first one
	setLinkTagProperties(link, 0);
	
	return false;
}

/**************************************************************************/
function getActiveStyleSheet() {
   	link = getFirstStyleSheetLink();
	if (!link) 
		return "";
	else
		return link.getAttribute("title");
}

function getPreferredStyleSheet() {
  return stylesheets[0];
}

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;
}

var set = false;

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

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

if (!set) {
    set = true;
	var cookie = readCookie("style");
	var title = cookie ? cookie : getPreferredStyleSheet();
	setActiveStyleSheet(title);
}
/**************************************************************************/