// Create scrolling variable if it doesn't exist
if (!Scrolling) var Scrolling = {};

//Scrollbar constructor
Scrolling.Scrollbar = function (o, s, t) {
        //private variables
        var self = this;
        var _components = {};
        var _dimensions = {};
        var _temporary  = {};
        var _hasTween   = t ? true : false;
        var _timer, _ratio;
        
        //public variables
        this.onMouseDown   = function (){};
        this.onMouseUp     = function (){};
        this.onScroll      = function (){};
        this.scrollAmount  = 5;
        this.scrollSpeed   = 30;
        this.disabled      = false;
        
        //private functions
        function initialize () {
                var c = _components;
                var d = _dimensions;
                var g = s.getDimensions();

                c.up     = findComponent("Scrollbar-Up", o);
                c.down   = findComponent("Scrollbar-Down", o);
                c.track  = findComponent("Scrollbar-Track", o);
                c.handle = findComponent("Scrollbar-Handle", c.track);
                
                d.trackTop     = findOffsetTop(c.track);
                d.trackHeight  = c.track.offsetHeight;
                d.handleHeight = c.handle.offsetHeight;
                d.y = 0
                
                if (_hasTween) t.apply(self);
                
                addEvent(s.getContent(), "mousewheel", scrollbarWheel);
                addEvent(s.getContent(), "DOMMouseScroll", scrollbarWheel);
                addEvent(o, "mousedown", scrollbarClickPrimer);
                
                self.reset();
        };
        
        function findOffsetTop (o) {
                var t = 0;
                if (o.offsetParent) {
                        while (o.offsetParent) {
                                t += o.offsetTop;
                                o  = o.offsetParent;
                        }
                }
                return t;
        };
        
        function addEvent (o, t, f) {
                if (o.attachEvent) o.attachEvent('on'+ t, f);
                else o.addEventListener(t, f, false);
        };
        
        function removeEvent (o, t, f) {
                if (o.detachEvent) o.detachEvent('on'+ t, f);
                else o.removeEventListener(t, f, false);
        };
        
        function findComponent (c, o) {
                var kids = o.childNodes;
                for (var i = 0; i < kids.length; i++) {
                        if (kids[i].className && kids[i].className.indexOf(c) >= 0) {
                                return kids[i];
                        }
                }
        };
        
        function scroll (y) {
                if (y < 0) y = 0;
                if (y > _dimensions.trackHeight - _dimensions.handleHeight)
                        y = _dimensions.trackHeight - _dimensions.handleHeight;

                _components.handle.style.top = y +"px";
                _dimensions.y = y;
                
                s.scrollTo(0, Math.round(_dimensions.y * _ratio));
                self.onScroll();
        };
        
        function scrollbarClickPrimer (e) {
                if (self.disabled) return false;
                
                e = e?e:event;
                if (!e.target) e.target = e.srcElement;
                
                _dimensions.trackTop = findOffsetTop(_components.track);
                scrollbarClick(e.target.className, e);
        };
        
        function scrollbarClick (c, e) {
                var d  = _dimensions;
                var t  = _temporary;
                var cy = e.clientY + document.body.scrollTop;
                
                if (c.indexOf("Scrollbar-Up") >= 0)
                        startScroll(-self.scrollAmount);
                
                if (c.indexOf("Scrollbar-Down") >= 0) 
                        startScroll(self.scrollAmount);
                        
                if (c.indexOf("Scrollbar-Track") >= 0)
                        if (_hasTween) self.tweenTo((cy - d.trackTop - d.handleHeight / 2) * _ratio);
                        else scroll(cy - d.trackTop - d.handleHeight / 2);        
                
                if (c.indexOf("Scrollbar-Handle") >= 0) {
                        t.grabPoint = cy - findOffsetTop(_components.handle);
                        addEvent(document, "mousemove", scrollbarDrag, false);        
                }
                
                t.target = e.target;
                t.select = document.onselectstart;
                
                document.onselectstart = function (){ return false; };
                self.onMouseDown(e.target, c, e);
                
                addEvent(document, "mouseup", stopScroll);
        };
        
        function scrollbarDrag (e) {
                e = e?e:event;
                var d = _dimensions;
                var t = parseInt(_components.handle.style.top);
                var v = e.clientY + document.body.scrollTop - d.trackTop;
                
                if (v >= d.trackHeight - d.handleHeight + _temporary.grabPoint)
                        v = d.trackHeight - d.handleHeight;
                        
                else if (v <= _temporary.grabPoint)
                        v = 0;
                        
                else v = v - _temporary.grabPoint;
                        
                scroll(v);
        };
        
        function scrollbarWheel (e) {
                if (self.disabled) return false;
                
                e = e ? e : event;
                var dir = 0;
                
                if (typeof e.wheelDelta == 'undefined') {
                        if (e.detail > 0) dir = 1;
                        if (e.detail < 0) dir = -1;
                } else {
                        if (e.wheelDelta >= 120) dir = -1;
                        if (e.wheelDelta <= -120) dir = 1;
                }

                self.scrollBy(dir * 20);
                
                if(e.stopPropagation) e.stopPropagation();
                if(e.preventDefault) e.preventDefault();
                e.cancelBubble = true;
                e.cancel = true;
                e.returnValue = false;
                return false;
        };
        
        function startScroll (y) {
                _temporary.disty = y;
                _timer = window.setInterval(function () {
                        self.scrollBy(_temporary.disty);
                }, self.scrollSpeed);
        };
        
        function stopScroll (e) {
                e = e?e:event;
                
                removeEvent(document, "mousemove", scrollbarDrag);
                removeEvent(document, "mouseup", stopScroll);
                
                document.onselectstart = _temporary.select;
                if (_timer) window.clearInterval(_timer);
                
                self.onMouseUp(_temporary.target, _temporary.target.className, e);
        };
        
        //public functions
        this.reset = function () {
                var d = _dimensions;
                var c = _components;
                var g = s.getDimensions();
                
                _ratio = (g.theight - g.vheight) / (d.trackHeight - d.handleHeight);
                
                c.handle.ondragstart = function (){ return false; };
                c.handle.onmousedown = function (){ return false; };
                c.handle.style.top   = "0px";
                d.y = 0;
                
                s.reset();
                scroll(0);
                
                if (g.theight < g.vheight) {
                        this.disable()
                } else this.enable();
        };
        
        this.scrollTo = function (y) {
                scroll(y / _ratio);
        };
        
        this.scrollBy = function (y) {
                scroll((s.getDimensions().y + y) / _ratio);
        };
        
        this.swapContent = function (n) {
                var d = s.getDimensions
                s.swapContent(n, d.vwidth, d.vheight);
                initialize();
        };
        
        this.disable = function () {
                this.disabled = true;
                o.className  += "Scrollbar-Disabled";
                document.getElementById("Scroller-1").style.width = "558px";
        };
        
        this.enable = function () {
                this.disabled = false;
                o.className = o.className.replace(/Scrollbar\-Disabled/, "");
        };
        
        this.getContent = function () {
                return s.getContent();
        };
        
        this.getComponents = function () {
                return _components;
        };
        
        this.getDimensions = function () {
                var d = s.getDimensions();
                d.trackHeight  = _dimensions.trackHeight;
                d.handleHeight = _dimensions.handleHeight;
                d.handleY = _dimensions.y;
                
                return d;
        };
        
        initialize();
};