//
 // Redirect to a Random Book
 // maintained by [[User:Darklama|darklama]]
 //
 
 // Gets a page from the wiki and runs function action on it
 function GetPage(page, action)
 {
   var doc = new XMLHttpRequest();
      
   if (doc) {
     var url = wgArticlePath.replace(/\$1$/, page);
     doc.onreadystatechange = function() { action(doc); };
     doc.open('GET', url+'?printable=true',  true);
     if (doc.overrideMimeType)
       doc.overrideMimeType('text/xml');
     else
       doc.setRequestHeader("Content-Type", "text/xml; charset=UTF-8");
     doc.send(null); 
   }
 }
 
 // Get a random page from Wikibooks:Alphabetical_classification
 function RandomBook()
 {
   function random_book(doc) {
     try {
       if (doc.readyState == 4 && doc.status == 200)
       {
         var wiki = doc.responseXML;
         if (wiki)
         {
           var books = wiki.getElementById('books').getElementsByTagName('li');
           if (books && books.length > 0) {
             var page = books.item(Math.floor(Math.random() * books.length + 1)).firstChild;
             while (hasClass(page, "new") || hasClass(page, "external")) {
               page = books.item(Math.floor(Math.random() * books.length + 1)).firstChild;
             }
             window.location = page.href;
           }
         }
       }
     } catch (e) { }
   }
   GetPage("Wikibooks:Alphabetical_classification", random_book);
 }
 
 // Adds a random book link to the navigation toolbar and calls RandomBook when clicked
 function RandomBookLink() {
   var tb = document.getElementById('p-Navigation');
   var link = document.createElement('a');
   var li = document.createElement('li');
   
   if (tb) {
     tb = tb.getElementsByTagName('ul')[0];
     link.title = "Random Book";
     link.href = "javascript:RandomBook();";
     link.onmouseover = function() { window.status = "Random Book"; return true; }
     link.onmouseout = function() { window.status = ""; return true; }
     if (link.addEventListener) {
       link.addEventListener("click", RandomBook, false);
     } else if (link.attachEvent) {
       link.attachEvent("onclick", function() { RandomBook(); });
     } else if (link.onclick) {
       link.onclick = function() { RandomBook(); }
     }
     link.appendChild(document.createTextNode("Random book"));
     li.id = "n-random-book";
     li.appendChild(link);
     tb.appendChild(li);
   }
 }
 
 addOnloadHook( RandomBookLink );