jQuery DropDown Menu

/*
    jQuery DropDown menu
*/
var ddmenu={
    buildmenu:function(menuid){
        $(document).ready(function($){
            var $mainmenu=$("#"+menuid+">ul");
            $mainmenu.children('li:first').addClass('first');
            $mainmenu.children('li:last').addClass('last');

            $("#"+menuid+">ul>li.parent").each(function(){
                var level2 = $(this).find('ul:eq(0)');
                if ( level2.width() < $(this).outerWidth(true) ) {
                    level2.width($(this).outerWidth(true));
                }
            });

            var $headers=$mainmenu.find("ul").parent();
            $headers.each(function(i){
                var $subul=$(this).find('ul:eq(0)');
                this._dimensions={
                    w:this.offsetWidth,
                    h:this.offsetHeight,
                    subulw:$subul.outerWidth(),
                    subulh:$subul.outerHeight()
                }
                this.istopheader=$(this).parents("ul").length==1? true : false;
                $subul.css({top:this.istopheader? this._dimensions.h+"px" : 0});

                $(this).hover(
                    function(e){
                        $(this).addClass('ddhover').children("a").addClass('ddhover');
                        var $targetul=$(this).children("ul:eq(0)");
                        if ( $(this).data('direction') ) {
                            this._offsets={
                                right:$(this).offset().right,
                                top:$(this).offset().top
                            }
                            var menuright=this.istopheader? 0 : this._dimensions.w;
                            menuright=(this._offsets.right+menuright+this._dimensions.subulw>$(window).width())? (this.istopheader? -this._dimensions.subulw+this._dimensions.w : -this._dimensions.w) : menuright;
                            $targetul.css({
                                right:menuright+"px",
                                width:this._dimensions.subulw+'px',
                                visibility: 'visible'
                            });
                        } else {
                            this._offsets={
                                left:$(this).offset().left,
                                top:$(this).offset().top
                            }
                            var menuleft=this.istopheader? 0 : this._dimensions.w;
                            menuleft=(this._offsets.left+menuleft+this._dimensions.subulw>$(window).width())? (this.istopheader? -this._dimensions.subulw+this._dimensions.w : -this._dimensions.w) : menuleft;
                            $targetul.css({
                                left:menuleft+"px",
                                width:this._dimensions.subulw+'px',
                                visibility: 'visible'
                            });
                        }
                    },
                    function(e){
                        $(this).children("ul:eq(0)").css('visibility', 'hidden');
                        $(this).removeClass('ddhover').children("a:eq(0)").removeClass('ddhover');
                    }
                ); //end hover
                $(this).click(function(){
                    $(this).children("ul:eq(0)").hide()
                });
            }); //end $headers.each()
        });
    }
}
ddmenu.buildmenu("menu");