var bannerCount = 3;
var randomNumber;
var currentBannerNumber = '';

sfHover = function() {
	var sfEls = document.getElementById('main_navigation').getElementsByTagName('LI');
	for (var i=0; i<sfEls.length; i++) {
		sfEls[i].onmouseover=function() {
			this.className+=' sfhover';
		}
		sfEls[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(' sfhoverb'), '');
		}
	}
}



//	Grab the list items in the main navigation list and run hide or show functions as appropriate.
function drop_down() {
	//	Make sure browser is capable to doing the things we need.
	if(!document.getElementsByTagName) return false;
	if(!document.getElementById) return false;
	
	//	Do the class changes as appropriate.
	var list_items = document.getElementById("main_navigation").getElementsByTagName("li");
	var i = 0;
	while (i < list_items.length) 
	{
		list_items[i].onmouseover=function() 
		{
			this.className+=" drop_down";
		}
		list_items[i].onmouseout=function() 
		{
			this.className=this.className.replace(new RegExp(" drop_down\\b"), ""); 
		}
		
		i++;
	}
}


function switch_banner() {
	 //this function gets all divs in a page and checks their classes
	 //if the div has a banner class it is added to a bannerDivs array
	 //a function is then called that displays a random banner
	 
	  var divs = document.getElementsByTagName("div");
		var bannerDivs = new Array();
		var classes;

		for ( var i=0; i<divs.length; i++ ) {
				//there may be multiple class assignments
				//separates the div class into an array
				classes = divs[i].className.split(" ");
				
				//checks if div has a class of menu
				//if so, add it to menuDivs array
				if ( inArray("banner", classes) ) {bannerDivs.push(divs[i]);}
		}
		display_banner();
}

function inArray( value, array ) {
//passed a value and an array, this function returns true
//if the value is contained with in the array,
//false if it is not

	for ( var i = 0; i < array.length; i++ )
		if ( array[i] == value )
			return true;
	return false;
} 


function display_banner() {
//displays a random banner 

	randomNumber = Math.floor((Math.random() * bannerCount));
	randomNumber = randomNumber + 1;
	
	if (document.getElementById("placeholder")) {
		document.getElementById("placeholder").style.display = "none";
	}

	if (document.getElementById("banner_" + currentBannerNumber)) {
		document.getElementById("banner_" + currentBannerNumber).style.display = "none";
	}
	
	if (document.getElementById("banner_" + randomNumber)) {
		currentBannerNumber = randomNumber;														
		document.getElementById("banner_" + randomNumber).style.display = "block";
		}

	setTimeout("display_banner()", 5000);	
}

function show_hide(which)   {
//toggles visibility of an element
        if (document.getElementById(which)) {

           if (document.getElementById(which).style.display == "block") {
		      document.getElementById(which).style.display = "none";			
        	} else  {
		      document.getElementById(which).style.display = "block";
        	}
         }		
}


//adds functions to the windows onload event
function addOnload(newFunction) {
  var oldOnload = window.onload;
    // does window.onload exist
  if (typeof oldOnload == "function") {
            //overwriting existing onload
              window.onload = function() {
                  if (oldOnload) {oldOnload();}
                  newFunction();
              }
          }
          else {
              window.onload = newFunction;
          }
} 

addOnload(drop_down);
//addOnload(sfHover);
addOnload(switch_banner);


//if (window.attachEvent) window.attachEvent('onload', sfHover);