Object.extend(Prototype.Browser, {
  Safari: (function() {
    return navigator.appVersion.match(/Safari/) != null
  })(),
 
  version: (function() {
    if ( Prototype.Browser.WebKit ) {
    	window.console.log(navigator.appVersion);
      var version = navigator.appVersion.match(/Version\/([\d.]+) /);
      return parseFloat(version);
    }
 
    return 10
  })()
});
 
Prototype.History = Class.create({
  initialize: function(callback){
    this.historyCallback = callback;
    var current_hash = location.hash;
    
    this.historyCurrentHash = current_hash;
    if ((Prototype.Browser.IE) ) { // && (jQuery.browser.version < 8)
      // To stop the callback firing twice during initilization if no hash present
      if (this.historyCurrentHash == '') {
      this.historyCurrentHash = '#';
    }
    
      // add hidden iframe for IE
      $$("body").first().innerHTML += '<iframe id="proto_history" style="display: none;"></iframe>';
      var ihistory = $("proto_history");
      var iframe = ihistory.contentWindow.document;
      iframe.open();
      iframe.close();
      iframe.location.hash = current_hash;
    }
    else if (Prototype.Browser.WebKit && ( Prototype.Browser.version < 4 )) {
      // etablish back/forward stacks
      this.historyBackStack = [];
      this.historyBackStack.length = history.length;
      this.historyForwardStack = [];
      
      this.isFirst = true;
    }
    this.historyCallback(current_hash.replace(/^#/, ''));
    setInterval(this.historyCheck.bind(this), 100);
  },
  
  historyAddHistory: function(hash) {
    // This makes the looping function do something
    this.historyBackStack.push(hash);
    
    this.historyForwardStack.length = 0; // clear forwardStack (true click occured)
    this.isFirst = true;
  },
  
  historyCheck: function(){
    if ( Prototype.Browser.IE ) { // && (jQuery.browser.version < 8)
      // On IE, check for location.hash of iframe
      var ihistory = $("proto_history");
      var iframe = ihistory.contentDocument || ihistory.contentWindow.document;
      var current_hash = iframe.location.hash;
      if(current_hash != this.historyCurrentHash) {
      
        location.hash = current_hash;
        this.historyCurrentHash = current_hash;
        this.historyCallback(current_hash.replace(/^#/, ''));
        
      }
    } else if (Prototype.Browser.Safari && ( Prototype.Browser.version < 4 )) {
      if (!this.dontCheck) {
        var historyDelta = history.length - this.historyBackStack.length;
        
        if (historyDelta) { // back or forward button has been pushed
          this.isFirst = false;
          if (historyDelta < 0) { // back button has been pushed
            // move items to forward stack
            for (var i = 0; i < Math.abs(historyDelta); i++) this.historyForwardStack.unshift(this.historyBackStack.pop());
          } else { // forward button has been pushed
            // move items to back stack
            for (var i = 0; i < historyDelta; i++) this.historyBackStack.push(this.historyForwardStack.shift());
          }
          var cachedHash = this.historyBackStack[this.historyBackStack.length - 1];
          if (cachedHash != undefined) {
            this.historyCurrentHash = location.hash;
            this.historyCallback(cachedHash);
          }
        } else if (this.historyBackStack[this.historyBackStack.length - 1] == undefined && !this.isFirst) {
          // back button has been pushed to beginning and URL already pointed to hash (e.g. a bookmark)
          // document.URL doesn't change in Safari
          if (document.location.hash.indexOf('#') >= 0) {
            this.historyCallback(document.location.hash.split('#')[1]);
          } else {
            var current_hash = location.hash;
            this.historyCallback('');
          }
          this.isFirst = true;
        }
      }
    } else {
      // otherwise, check for location.hash
      var current_hash = location.hash;
      if(current_hash != this.historyCurrentHash) {
        this.historyCurrentHash = current_hash;
        this.historyCallback(current_hash.replace(/^#/, ''));
      }
    }
  },
  historyLoad: function(hash){
    var newhash;
    
    if (Prototype.Browser.WebKit && ( Prototype.Browser.version < 4 )) {
      newhash = hash;
    }
    else {
      newhash = '#' + hash;
      location.hash = newhash;
    }
    this.historyCurrentHash = newhash;
    
    if ((Prototype.Browser.IE)) { // && (jQuery.browser.version < 8)
      var ihistory = $("proto_history");
      var iframe = ihistory.contentWindow.document;
      iframe.open();
      iframe.close();
      iframe.location.hash = newhash;
      this.historyCallback(hash);
    }
    else if (Prototype.Browser.WebKit && ( Prototype.Browser.version < 4 )) {
      this.dontCheck = true;
      // Manually keep track of the history values for Safari
      this.historyAddHistory(hash);
      
      // Wait a while before allowing checking so that Safari has time to update the "history" object
      // correctly (otherwise the check loop would detect a false change in hash).
      var fn = function() {this.dontCheck = false;};
      window.setTimeout(fn, 200);
      this.historyCallback(hash);
      // N.B. "location.hash=" must be the last line of code for Safari as execution stops afterwards.
      // By explicitly using the "location.hash" command (instead of using a variable set to "location.hash") the
      // URL in the browser and the "history" object are both updated correctly.
      location.hash = newhash;
    }
    else {
      this.historyCallback(hash);
    }
  }
});