/*
 * Supposition v0.2 - an optional enhancer for Superfish jQuery menu widget
 *
 * Copyright (c) 2008 Joel Birch - based mostly on work by Jesse Klaasse and credit goes largely to him.
 * Special thanks to Karl Swedberg for valuable input.
 *
 * Dual licensed under the MIT and GPL licenses:
 *     http://www.opensource.org/licenses/mit-license.php
 *     http://www.gnu.org/licenses/gpl.html
 */

(function($){

    $.fn.supposition = function(){
        var $w = $(window), /*do this once instead of every onBeforeShow call*/
            _offset = function(dir) {
                return window[dir == 'y' ? 'pageYOffset' : 'pageXOffset']
                || document.documentElement && document.documentElement[dir=='y' ? 'scrollTop' : 'scrollLeft']
                || document.body[dir=='y' ? 'scrollTop' : 'scrollLeft'];
            },
            onInit = function(){
                /* I haven't touched this bit - needs work as there are still z-index issues */
                $topNav = $('li',this);
                var cZ=parseInt($topNav.css('z-index')) + $topNav.length;
                $topNav.each(function() {
                    $(this).css({zIndex:--cZ});
                });
            },
            onHide = function(){
                this.css({marginTop:'',marginLeft:''});
            },
            onBeforeShow = function(){
                this.each(function(){
                    var $u = $(this);
                    $u.css('display','block');
                    var menuWidth = $u.width(),
                        parentWidth = $u.parents('ul').width(),
                        totalRight = $w.width() + _offset('x'),
                        menuRight = $u.offset().left + menuWidth;
                    if (menuRight > totalRight) {
                        $u.css('margin-left', ($u.parents('ul').length == 1 ? totalRight - menuRight : -(menuWidth + parentWidth)) + 'px');
                    }

                    var windowHeight = $w.height(),
                        offsetTop = $u.offset().top,
                        menuHeight = $u.height(),
                        baseline = windowHeight + _offset('y');
                    var expandUp = (offsetTop + menuHeight > baseline);
                    if (expandUp) {
                        $u.css('margin-top',baseline - (menuHeight + offsetTop));
                    }
                    $u.css('display','none');
                });
            };
        
        return this.each(function() {
            var o = $.superfish.o[this.serial]; /* get this menu's options */
            
            /* if callbacks already set, store them */
            var _onInit = o.onInit,
                _onBeforeShow = o.onBeforeShow,
                _onHide = o.onHide;
                
            $.extend($.superfish.o[this.serial],{
                onInit        : function() {
                    onInit.call(this); /* fire our Supposition callback */
                    _onInit.call(this); /* fire stored callbacks */
                },
                onBeforeShow: function() {
                    onBeforeShow.call(this); /* fire our Supposition callback */
                    _onBeforeShow.call(this); /* fire stored callbacks */
                },
                onHide        : function() {
                    onHide.call(this); /* fire our Supposition callback */
                    _onHide.call(this); /* fire stored callbacks */
                }
            });
        });
    };

})(jQuery);