/*
 * found at http://www.alistapart.com/stories/alternate/
 * Folke extended 0.1 (comments, fallback to default, support of 'none')
 */

/* set stylesheet <title> and return true if found */
function setActiveStyleSheet2(title) {
  var i, a, main;
  var done=false;
  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;
	  done=true;
      }
    }
  }
  /* Folke: compliance to IE7 hacks (http://dean.edwards.name/IE7)
   * needs ie7-recalc.js (not included in ie7-standard-p.js)
   */
  if (document.recalc) document.recalc(true);
  return done;
}

/* set stylesheet <title> and failback to default if not found except if title=='none' */
function setActiveStyleSheet(title){
    if (!setActiveStyleSheet2(title) && title!="none"){
	setActiveStyleSheet2(getPreferredStyleSheet());
    }
}

/* returns the active stylesheet or 'none' if none loaded */
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 "none";
}

/* returns the default stylesheet */
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 null;
}

/* creates a cookie <name>=<value> valid for <days> days*/
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=/";
}

/* returns the value of cookie with <name> */
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;
}

/* changes stylesheet at page load based on cookie */
window.onload = function(e) {
  var cookie = readCookie("style");
  var title = cookie ? cookie : getPreferredStyleSheet();
  setActiveStyleSheet(title);
}

/* saves active stylesheet to cookie when page is left */
window.onunload = function(e) {
  var title = getActiveStyleSheet();
  createCookie("style", title, 365);
}

/* again change stylesheet based on cookie */
var cookie = readCookie("style");
var title = cookie ? cookie : getPreferredStyleSheet();
setActiveStyleSheet(title);