/*
* JavaScript responsible for activating the appropriate stylesheet.
*
* @last_modified 030816
* @author alistapart.com (modified and commented by Paul Hitz)
*/


/*
* Enable the specified stylesheet and disable all others (except the persistant stylesheet).
*/
function setActiveStyleSheet(title)
{
  var i, a, main;

  //Walk through every link tag in the page.
  for(i = 0; (a = document.getElementsByTagName("link")[i]); i++)
  {
    //Check if the current link tag links to a stylesheet with a title (i.e. a preferred or alternate stylesheet).
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title"))
    {
      a.disabled = true;

      //Enable the stylesheet if it is the one we are searching for.
      if(a.getAttribute("title") == title)
      {
        a.disabled = false;
      }
    }
  }

  //Set the style in the cookie.
  createCookie(title);
}


/*
* Gets the name of the current active stylesheet.
*/
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;
}


/*
* Return the title of the preferred stylesheet. 
* I.e. The stylesheet that should be used by default.
*/
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;
}


/*
* Create a cookie containing the stylesheets to use. Lasts 5 years.
*/
function createCookie(style)
{
  var date = new Date();
  date.setTime(date.getTime() + (3600 * 24 * 365 * 5));
  var expires = "expires="+date.toGMTString();

  document.cookie = "fontsize=" + style +"; "+ 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;
}


/*
* Retrieve the cookie and enable the appropriate stylesheet.
*/
window.onload = function(e) {
  var cookie = readCookie("fontsize");
  var title = cookie ? cookie : getPreferredStyleSheet();
  setActiveStyleSheet(title);
}


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