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 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 setBackground() {
	var activeStyle = getActiveStyleSheet();
	
	if (activeStyle == 'highcontrast')
		setActiveStyleSheet('highcontrastnoback');
	else if (activeStyle == 'highcontrastnoback')
		setActiveStyleSheet('highcontrast');
	else if (activeStyle == 'highcontrastlarge')
		setActiveStyleSheet('highcontrastlargenoback');
	else if (activeStyle == 'highcontrastlargenoback')
		setActiveStyleSheet('highcontrastlarge');
	else if (activeStyle == 'basiclarge')
		setActiveStyleSheet('basiclargenoback');
	else if (activeStyle == 'basiclargenoback')
		setActiveStyleSheet('basiclarge');
	else if (activeStyle == 'basicnoback')
		setActiveStyleSheet('default');
	else if (activeStyle == 'cold')
		setActiveStyleSheet('coldnoback');
	else if (activeStyle == 'coldnoback')
		setActiveStyleSheet('cold');
	else if (activeStyle == 'coldlargenoback')
		setActiveStyleSheet('coldlarge');
	else if (activeStyle == 'coldlarge')
		setActiveStyleSheet('coldlargenoback');
	else setActiveStyleSheet('basicnoback');
}


function setDefaultFont() {
	var activeStyle = getActiveStyleSheet();
	if (activeStyle == 'highcontrast')
		return null;
	else if (activeStyle == 'highcontrastlarge')
		setActiveStyleSheet('highcontrast');
	else if (activeStyle == 'highcontrastnoback')
		return null;
	else if (activeStyle == 'highcontrastlargenoback')
		setActiveStyleSheet('highcontrastnoback');
	else if (activeStyle == 'basicnoback')
		return null;
	else if (activeStyle == 'basiclargenoback')
		setActiveStyleSheet('basicnoback');
	else if (activeStyle == 'basiclarge')
		setActiveStyleSheet('default');
	else if (activeStyle == 'coldlargenoback')
		setActiveStyleSheet('coldnoback');
	else if (activeStyle == 'coldlarge')
		setActiveStyleSheet('cold');
}


function setLargerFont() {
	var activeStyle = getActiveStyleSheet();
	if (activeStyle == 'highcontrast')
		setActiveStyleSheet('highcontrastlarge');
	else if (activeStyle == 'highcontrastlarge')
		return null;
	else if (activeStyle == 'highcontrastnoback')
		setActiveStyleSheet('highcontrastlargenoback');
	else if (activeStyle == 'highcontrastlargenoback')
		return null;
	else if (activeStyle == 'basicnoback')
		setActiveStyleSheet('basiclargenoback');
	else if (activeStyle == 'basiclargenoback')
		return null;
	else if (activeStyle == 'coldnoback')
		setActiveStyleSheet('coldlargenoback');
	else if (activeStyle == 'coldlargenoback')
		return null;
	else if (activeStyle == 'cold')
		setActiveStyleSheet('coldlarge');
	else if (activeStyle == 'coldlarge')
		return null;
	else setActiveStyleSheet('basiclarge');
}

function setColour(title) {
	var activeStyle = getActiveStyleSheet();
	if (title == 'highcontrast') {
		if ((activeStyle == 'highcontrast') || (activeStyle == 'highcontrastnoback') || (activeStyle == 'highcontrastlarge') || (activeStyle == 'highcontrastlargenoback'))
			return null;
		else if ((activeStyle == 'basicnoback') || (activeStyle == 'coldnoback'))
			setActiveStyleSheet('highcontrastnoback');
		else if ((activeStyle == 'basiclargenoback') || (activeStyle == 'coldlargenoback'))
			setActiveStyleSheet('highcontrastlargenoback');
		else if ((activeStyle == 'basiclarge') || (activeStyle == 'coldlarge'))
			setActiveStyleSheet('highcontrastlarge');
		else
			setActiveStyleSheet('highcontrast');
	}
	else if (title == 'cold') {
		if ((activeStyle == 'cold') || (activeStyle == 'coldnoback') || (activeStyle == 'coldlarge') || (activeStyle == 'coldlargenoback'))
			return null;
		else if ((activeStyle == 'basicnoback') || (activeStyle == 'highcontrastnoback'))
			setActiveStyleSheet('coldnoback');
		else if ((activeStyle == 'basiclargenoback') || (activeStyle == 'highcontrastlargenoback'))
			setActiveStyleSheet('coldlargenoback');
		else if ((activeStyle == 'basiclarge') || (activeStyle == 'highcontrastlarge'))
			setActiveStyleSheet('coldlarge');
		else
			setActiveStyleSheet('cold');
	}
	else {
		if ((activeStyle == 'default') || (activeStyle == 'basicnoback') || (activeStyle == 'basiclarge') || (activeStyle == 'basiclargenoback'))
			return null;
		else if ((activeStyle == 'highcontrastnoback') || (activeStyle == 'coldnoback'))
			setActiveStyleSheet('basicnoback');
		else if ((activeStyle == 'highcontrastlargenoback') || (activeStyle == 'coldlargenoback'))
			setActiveStyleSheet('basiclargenoback');
		else if ((activeStyle == 'highcontrastlarge') || (activeStyle == 'coldlarge'))
			setActiveStyleSheet('basiclarge');
		else
			setActiveStyleSheet('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;
}

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);