/*
* jQuery verticalScroll
* Copyright (c) 2011 SaCaWeb www.sacaweb.com
* 
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:

* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE. 
*/

/*
* Version: V1.0
* Release: 23-02-2011
* Based on jQuery 1.4.2
*/

function changeBackImage(btnId, imgsrc) {

    if (btnId != null && imgsrc != null) {
        $(btnId).attr("src", imgsrc);
    }
}


(function ($) {
    $.fn.verticalScrollPlus = function (options) {

        var options = $.extend({}, { speed: 1000, step: 60, upID: "#up_btn_scroll", downID: "#down_btn_scroll", scrollerID: "#scroller",imgdownenabled:null, imgdowndisabled: null, imgupenabled:null, imgupdisabled: null }, options);

        return this.each(function () {

            if ($.cookie("scrollerPos") != null) {

                $(options.scrollerID).css("top", $.cookie("scrollerPos"));
                $.cookie("scrollerPos", null);
            }

            obj = $(this); //il wrapper
            obj.css("overflow", "hidden");
            obj.css("position", "relative");
            /*obj.css("height", options.height + "px");*/
            var wrapper_h = obj.outerHeight();
            var m_scroller_h = $(options.scrollerID).outerHeight();

            $(options.scrollerID).css("position", "absolute");


            if(m_scroller_h <= wrapper_h)
            {
                changeBackImage(options.upID,options.imgupdisabled);
                changeBackImage(options.downID,options.imgdowndisabled);
            }
           
            if(parseInt($(options.scrollerID).css("top")) < 0)
            {
                changeBackImage(options.upID,options.imgupenabled);

                if((parseInt($(options.scrollerID).css("top")) - wrapper_h) <= -m_scroller_h)
                {
                    changeBackImage(options.downID,options.imgdowndisabled);
                }
            }



            $(options.scrollerID).mousewheel(function (event, delta) {

                event.preventDefault();
                if (delta > 0) {

                    var scroller_h = $(options.scrollerID).outerHeight();

                    if (scroller_h > wrapper_h) {
                       changeBackImage(options.downID,options.imgdownenabled);
                    }

                    var scroller_top = parseInt($(options.scrollerID).css("top"));

                    var offset = scroller_top + wrapper_h;

                    if (offset > 0) {
                        $(options.scrollerID).stop().animate({ top: 0 }, options.speed);
                         changeBackImage(options.upID,options.imgupdisabled);
                        return;
                    }

                    $(options.scrollerID).stop().animate({
                        top: "+=" + 32 + "px"
                    }, 100);
                    changeBackImage(options.downID,options.imgdownenabled);

                } else {

                    var scroller_h = $(options.scrollerID).outerHeight();

                    if (scroller_h < wrapper_h) {
                        return;
                    }

                    changeBackImage(options.upID,options.imgupenabled);

                    var scroller_top2 = parseInt($(options.scrollerID).css("top"));

                    if ((scroller_top2 - wrapper_h - options.step) < -scroller_h) {
                        var offset2 = scroller_h - wrapper_h;
                        $(options.scrollerID).stop().animate({ top: "-" + offset2 + "px" }, options.speed);

                        changeBackImage(options.downID,options.imgdowndisabled);

                        return;
                    }

                    $(options.scrollerID).stop().animate({
                        top: "-=" + 32 + "px"
                    }, 100);
                    
                }

                return false;
            });



            $(options.downID).click(function () {

               
                var scroller_h = $(options.scrollerID).outerHeight();

                if (scroller_h < wrapper_h) {
                    return;
                }

                changeBackImage(options.upID,options.imgupenabled);

                var scroller_top2 = parseInt($(options.scrollerID).css("top"));

                if ((scroller_top2 - wrapper_h - options.step) < -scroller_h) {
                    var offset2 = scroller_h - wrapper_h;
                    $(options.scrollerID).stop().animate({ top: "-" + offset2 + "px" }, options.speed);

                    changeBackImage(options.downID,options.imgdowndisabled);

                    return;
                }

                $(options.scrollerID).stop().animate({
                    top: "-=" + options.step + "px"
                }, options.speed);

                
            });


            $(options.upID).click(function () {
                
                var scroller_h = $(options.scrollerID).outerHeight();

                if (scroller_h > wrapper_h) {
                   changeBackImage(options.downID,options.imgdownenabled);
                }

                var scroller_top = parseInt($(options.scrollerID).css("top"));

                var offset = scroller_top + wrapper_h;

                if (offset > 0) {
                    $(options.scrollerID).stop().animate({ top: 0 }, options.speed);

                    changeBackImage(options.upID,options.imgupdisabled);
                    return;
                }

                $(options.scrollerID).stop().animate({
                    top: "+=" + options.step + "px"
                }, options.speed);

                
            });

        });

    };

})(jQuery);