(function($){

    $.ui = $.ui || {};
    
    $.ui.accordion = {};
    $.extend($.ui.accordion, {
        defaults: {
            selectedClass: "selected",
            alwaysOpen: true,
            animated: 'slide',
            event: "click",
            header: "a",
            autoheight: true
        },
        animations: {
            slide: function(settings, additions){
                settings = $.extend({
                    easing: "swing",
                    duration: 300
                }, settings, additions);
                if (!settings.toHide.size()) {
                    settings.toShow.animate({
                        height: "show"
                    }, {
                        duration: settings.duration,
                        easing: settings.easing,
                        complete: settings.finished
                    });
                    return;
                }
                var hideHeight = settings.toHide.height(), showHeight = settings.toShow.height(), difference = showHeight / hideHeight;
                settings.toShow.css({
                    height: 0,
                    overflow: 'hidden'
                }).show();
                settings.toHide.filter(":hidden").each(settings.finished).end().filter(":visible").animate({
                    height: "hide"
                }, {
                    step: function(now){
                        settings.toShow.height((hideHeight - (now)) * difference);
                    },
                    duration: settings.duration,
                    easing: settings.easing,
                    complete: settings.finished
                });
            },
            bounceslide: function(settings){
                this.slide(settings, {
                    easing: settings.down ? "bounceout" : "swing",
                    duration: settings.down ? 1000 : 200
                });
            },
            easeslide: function(settings){
                this.slide(settings, {
                    easing: "easeinout",
                    duration: 700
                })
            }
        }
    });
    
    $.fn.extend({
        accordion: function(settings){
            if (!this.length) 
                return this;
            
            // setup configuration
            settings = $.extend({}, $.ui.accordion.defaults, settings);
            
            if (settings.navigation) {
                var current = this.find("a").filter(function(){
                    return this.href == location.href;
                });
                if (current.length) {
                    if (current.filter(settings.header).length) {
                        settings.active = current;
                    }
                    else {
                        settings.active = current.parent().parent().prev();
                        current.addClass("current");
                    }
                }
            }
            
            // calculate active if not specified, using the first header
            var container = this, headers = container.find(settings.header), active = findActive(settings.active), running = 0;
            
            if (settings.fillSpace) {
                var maxHeight = this.parent().height();
                headers.each(function(){
                    maxHeight -= $(this).outerHeight();
                });
                var maxPadding = 0;
                headers.next().each(function(){
                    maxPadding = Math.max(maxPadding, $(this).innerHeight() - $(this).height());
                }).height(maxHeight - maxPadding);
            }
            else 
                if (settings.autoheight) {
                    var maxHeight = 0;
                }
            
            headers.not(active || "").next().hide();
            active.parent().andSelf().addClass(settings.selectedClass);
            
            
            function findActive(selector){
                return selector != undefined ? typeof selector == "number" ? headers.filter(":eq(" + selector + ")") : headers.not(headers.not(selector)) : selector === false ? $("<div>") : headers.filter(":eq(0)");
            }
            
            function toggle(toShow, toHide, data, clickedActive, down){
                var finished = function(cancel){
                    running = cancel ? 0 : --running;
                    if (running) 
                        return;
                    // trigger custom change event
                    container.trigger("change", data);
                };
                
                // count elements to animate
                running = toHide.size() == 0 ? toShow.size() : toHide.size();
                
                if (settings.animated) {
                    if (!settings.alwaysOpen && clickedActive) {
                        toShow.slideToggle(settings.animated);
                        finished(true);
                    }
                    else {
                        $.ui.accordion.animations[settings.animated]({
                            toShow: toShow,
                            toHide: toHide,
                            finished: finished,
                            down: down
                        });
                    }
                }
                else {
                    if (!settings.alwaysOpen && clickedActive) {
                        toShow.toggle();
                    }
                    else {
                        toHide.hide();
                        toShow.show();
                    }
                    finished(true);
                }
            }
            
            function clickHandler(event){
                // called only when using activate(false) to close all parts programmatically
                if (!event.target && !settings.alwaysOpen) {
                    active.parent().andSelf().toggleClass(settings.selectedClass);
                    var toHide = active.next();
                    var toShow = active = $([]);
                    toggle(toShow, toHide);
                    return;
                }
                // get the click target
                var clicked = $(event.target);
                
                // due to the event delegation model, we have to check if one
                // of the parent elements is our actual header, and find that
                if (clicked.parents(settings.header).length) 
                    while (!clicked.is(settings.header)) 
                        clicked = clicked.parent();
                
                var clickedActive = clicked[0] == active[0];
                
                // if animations are still active, or the active header is the target, ignore click
                if (running || (settings.alwaysOpen && clickedActive) || !clicked.is(settings.header)) 
                    return;
                
                // switch classes
                active.parent().andSelf().toggleClass(settings.selectedClass);
                if (!clickedActive) {
                    clicked.parent().andSelf().addClass(settings.selectedClass);
                }
                
                // find elements to show and hide
                var toShow = clicked.next(), toHide = active.next(), data = [clicked, active, toShow, toHide], down = headers.index(active[0]) > headers.index(clicked[0]);
                
                active = clickedActive ? $([]) : clicked;
                toggle(toShow, toHide, data, clickedActive, down);
                
                return false;
            };
            function activateHandler(event, index){
                // IE manages to call activateHandler on normal clicks
                if (arguments.length == 1) 
                    return;
                // call clickHandler with custom event
                clickHandler({
                    target: findActive(index)[0]
                });
            };
            
            return container.bind(settings.event || "", clickHandler).bind("activate", activateHandler);
        },
        activate: function(index){
            return this.trigger('activate', [index]);
        },
        unaccordion: function(){
            return this.find("*").andSelf().unbind().end().end();
        }
    });
    
})(jQuery);