/* initialize ourselves when the page is finished loading */
window.onload = initialize;

/* Our function that initializes when the page is finished loading. */
function initialize() {
   dhtmlHistory.initialize();	// initialize the DHTML History framework
   dhtmlHistory.addListener(handleHistoryChange); // add ourselves as a DHTML History listener

   /* subscribe to mouse clicks on the menu */
   var menu = document.getElementById("menu");
   var submenu = document.getElementById("submenu");
   if (typeof window.attachEvent != "undefined") { /* Internet Explorer */ 
      menu.attachEvent("onclick", handleMouseClick);
      submenu.attachEvent("onclick", handleMouseClick);
   } else { /* W3C standards */
      menu.addEventListener("click", handleMouseClick, false);
      submenu.addEventListener("click", handleMouseClick, false);
   }
   
   /* determine what our initial location is by retrieving it from the browser's
      location after the hash */
   var currentLocation = dhtmlHistory.getCurrentLocation();
      
   /* if there is no location then display the default, which is home */
   if (currentLocation == "") {
      currentLocation = "section:home";
   }
   
   /* extract the section to display from the initial location */
   currentLocation = currentLocation.replace(/section\:/, "");
   /* display this initial location */
   displayLocation(currentLocation, null);
}

/* Handles history change events. */
function handleHistoryChange(newLocation, historyData) {
   /* if there is no location then display the default, which is the inbox */
   if (newLocation == "") {
      newLocation = "section:home";
   }
   
   /* extract the section to display from the location change; newLocation will
      begin with the word "section:" */
   newLocation = newLocation.replace(/section\:/, ""); 
   
   /* update the browser to respond to this DHTML history change */
   displayLocation(newLocation, historyData);
}

/* Displays the given location in the right-hand side content area. */
function displayLocation(newLocation, sectionData) {
  	ajaxload("pages/"+newLocation+".html", "content");
}

/* Responds to mouse clicks on the left-hand side menu area. */
function handleMouseClick(e) {
//alert("handleMouseClick()");
   /* normalize events */
   var evt;
   if (typeof window.event != "undefined") // IE
      evt = window.event;
   else // W3C
      evt = e;
      
   // normalize event target
   var target;
   if (typeof evt.srcElement != "undefined") // IE
      target = evt.srcElement;
   else // W3C
      target = evt.target;
      
   // get the location the user clicked on
   var newLocation = target.id;
   
   /* Register a history event so this action gets recorded in the browser; Internet
      Explorer has a bug that prevents us from setting a location value if there
   	are ANY HTML elements in the document that have the same ID already. For example,
   	if we tell dhtmlHistory to add the location 'inbox' to our browser's history, and there
   	is an element in the document with the ID 'inbox', then Internet Explorer will 
   	misbehave. We must accomodate this problem in IE by changing the location so it does
   	not match a pre-existing HTML id */
   var modifiedLocation = "section:" + newLocation;
   
   var historyData = "<p>The following location was loaded from our DHTML history: "+modifiedLocation+"</p>";
   dhtmlHistory.add(modifiedLocation, historyData);
   
   // display this location
   displayLocation(newLocation, null);
}