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")) {
      if (a.getAttribute("title") != 'kontrast') {
      	a.disabled = true;
        if(a.getAttribute("title") == title) a.disabled = false;
      } else {
      	a.disabled = false;      	
      }
    }
  }
}

function switchActiveStyleSheetKontrast() {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && a.getAttribute("title") == 'kontrast') {
      a.disabled = a.disabled ? false : true;
      document.getElementById('kontrast_waehler').src = a.disabled ? weitere_ebene + 'img/icon_plus.gif' : weitere_ebene + 'img/icon_minus.gif';
    }
  }
}

function setActiveStyleSheetKontrast(deactivate) {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && a.getAttribute("title") == 'kontrast') {
      a.disabled = true;
      if (deactivate == 'false')
      {
      	a.disabled = false;
      }
      document.getElementById('kontrast_waehler').src = a.disabled ? weitere_ebene + 'img/icon_plus.gif' : weitere_ebene + 'img/icon_minus.gif';
    }
  }
}

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

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 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);  
  
  var cookie_kontrast = readCookie("kontrast");
  var kontrast = cookie_kontrast ? cookie_kontrast : true;
  setActiveStyleSheetKontrast(kontrast);
}

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

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