// Initialize and render the MenuBar when it is available in the page

YAHOO.util.Event.onContentReady("menu", function () {

    /*
         Instantiate a MenuBar.  The first argument passed to the 
         constructor is the id of the element in the page that 
         represents the MenuBar; the second is an object literal 
         representing a set of configuration properties.
    */

    var oMenuBar = new YAHOO.widget.MenuBar("menu", { 
                                            autosubmenudisplay: true, 
                                            lazyload: true });

    /*
         Call the "render" method with no arguments since the 
         markup for this MenuBar already exists in the page.
    */

    oMenuBar.render();

	/*
	     Subscribe to the "beforeShow" and "show" events for 
	     each submenu of the MenuBar instance.
	*/
	
	oMenuBar.subscribe("beforeShow", onSubmenuBeforeShow);
	oMenuBar.subscribe("show", onSubmenuShow);

});

var ua = YAHOO.env.ua,
    oAnim;  // Animation instance


/*
     "beforeshow" event handler for each submenu of the MenuBar
     instance, used to setup certain style properties before
     the menu is animated.
*/

function onSubmenuBeforeShow(p_sType, p_sArgs) {

    var oBody,
        oElement,
        oShadow,
        oUL;


    if (this.parent) {

        oElement = this.element;

        /*
             Get a reference to the Menu's shadow element and 
             set its "height" property to "0px" to syncronize 
             it with the height of the Menu instance.
        */

        oShadow = oElement.lastChild;
        oShadow.style.height = "0px";

        
        /*
            Stop the Animation instance if it is currently 
            animating a Menu.
        */ 
    
        if (oAnim && oAnim.isAnimated()) {
        
            oAnim.stop();
            oAnim = null;
        
        }


        /*
            Set the body element's "overflow" property to 
            "hidden" to clip the display of its negatively 
            positioned <ul> element.
        */ 

        oBody = this.body;


        //  Check if the menu is a submenu of a submenu.

        if (this.parent && 
            !(this.parent instanceof YAHOO.widget.MenuBarItem)) {
        

            /*
                There is a bug in gecko-based browsers where 
                an element whose "position" property is set to 
                "absolute" and "overflow" property is set to 
                "hidden" will not render at the correct width when
                its offsetParent's "position" property is also 
                set to "absolute."  It is possible to work around 
                this bug by specifying a value for the width 
                property in addition to overflow.
            */

            if (ua.gecko) {
            
                oBody.style.width = oBody.clientWidth + "px";
            
            }
            
            
            /*
                Set a width on the submenu to prevent its 
                width from growing when the animation 
                is complete.
            */
            
            if (ua.ie == 7) {

                oElement.style.width = oElement.clientWidth + "px";

            }
        
        }


        oBody.style.overflow = "hidden";


        /*
            Set the <ul> element's "marginTop" property 
            to a negative value so that the Menu's height
            collapses.
        */ 

        oUL = oBody.getElementsByTagName("ul")[0];

        oUL.style.marginTop = ("-" + oUL.offsetHeight + "px");
    
    }

}


/*
    "tween" event handler for the Anim instance, used to 
    syncronize the size and position of the Menu instance's 
    shadow and iframe shim (if it exists) with its 
    changing height.
*/

function onTween(p_sType, p_aArgs, p_oShadow) {

    if (this.cfg.getProperty("iframe")) {
    
        this.syncIframe();

    }

    if (p_oShadow) {

        p_oShadow.style.height = this.element.offsetHeight + "px";
    
    }

}


/*
    "complete" event handler for the Anim instance, used to 
    remove style properties that were animated so that the 
    Menu instance can be displayed at its final height.
*/

function onAnimationComplete(p_sType, p_aArgs, p_oShadow) {

    var oBody = this.body,
        oUL = oBody.getElementsByTagName("ul")[0];

    if (p_oShadow) {
    
        p_oShadow.style.height = this.element.offsetHeight + "px";
    
    }


    oUL.style.marginTop = "";
    oBody.style.overflow = "";
    

    //  Check if the menu is a submenu of a submenu.

    if (this.parent && 
        !(this.parent instanceof YAHOO.widget.MenuBarItem)) {


        // Clear widths set by the "beforeshow" event handler

        if (ua.gecko) {
        
            oBody.style.width = "";
        
        }
        
        if (ua.ie == 7) {

            this.element.style.width = "";

        }
    
    }
    
}


/*
     "show" event handler for each submenu of the MenuBar 
     instance - used to kick off the animation of the 
     <ul> element.
*/

function onSubmenuShow(p_sType, p_sArgs) {

    var oElement,
        oShadow,
        oUL;

    if (this.parent) {

        oElement = this.element;
        oShadow = oElement.lastChild;
        oUL = this.body.getElementsByTagName("ul")[0];
    

        /*
             Animate the <ul> element's "marginTop" style 
             property to a value of 0.
        */

        oAnim = new YAHOO.util.Anim(oUL, 
            { marginTop: { to: 0 } },
            .5, YAHOO.util.Easing.easeOut);


        oAnim.onStart.subscribe(function () {

            oShadow.style.height = "100%";
        
        });


        oAnim.animate();


        /*
            Subscribe to the Anim instance's "tween" event for 
            IE to syncronize the size and position of a 
            submenu's shadow and iframe shim (if it exists)  
            with its changing height.
        */

        if (YAHOO.env.ua.ie) {
            
            oShadow.style.height = oElement.offsetHeight + "px";


            /*
                Subscribe to the Anim instance's "tween"
                event, passing a reference Menu's shadow 
                element and making the scope of the event 
                listener the Menu instance.
            */

            oAnim.onTween.subscribe(onTween, oShadow, this);

        }


        /*
            Subscribe to the Anim instance's "complete" event,
            passing a reference Menu's shadow element and making 
            the scope of the event listener the Menu instance.
        */

        oAnim.onComplete.subscribe(onAnimationComplete, oShadow, this);
    
    }

}