//
// Methods
//


// Switch styles

function setActiveStyleSheet(title) {
    var i, a, main;

    for (i = 0; (a = document.getElementsByTagName("link")[i]); i++) {
        if (a.getAttribute("rel") &&
            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") &&
            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") &&
            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;
}


//
// Event handlers
//


// Set the preferred style sheet on page load

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

// Save the preferred style sheet on page unload

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


//
// Simulate a page load, just in case window.onload is unsupported
//


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

setActiveStyleSheet(title);