(function($)
{
  jQuery.extend(
  {
    edotScrollBar: function(settings)
    {
      settings = jQuery.extend(
      {
        mousewheel         : true,
        relativeDivId      : "scrollbarContainer",
        absoluteDivId      : "scrollbarElement",
        scrollButtonUpId   : "scrollbarUp",
        scrollButtonDownId : "scrollbarDown",
        buttonStepPx       : 5,
        mouseStepPx        : 10,
        scrollbarDelay     : 15
      },settings);

      var relative   = $("#" + settings.relativeDivId);
      var absolute   = $("#" + settings.absoluteDivId);
      var buttonUp   = $("#" + settings.scrollButtonUpId);
      var buttonDown = $("#" + settings.scrollButtonDownId);
      
      if (!absolute || absolute.length == 0 || !relative || relative.length == 0) return;

      var relativeHeight = relative.height();
      var aOffset = absolute.offset({margin: true});
      var rOffset = relative.offset({margin: true});
      var absoluteHeight = absolute.height();
      absoluteHeight += Math.abs(aOffset.top - rOffset.top);

      var maxTop = relativeHeight - absoluteHeight;

      var timer;

      jQuery.edotScrollBar.scroll = function(direction)
      {
        /**
         * Needs to recalculate because of changing contents
         */
        absoluteHeight = absolute.height();
        absoluteHeight += Math.abs(aOffset.top - rOffset.top);
        maxTop = relativeHeight - absoluteHeight;
      
        if (maxTop >= 0) return;
        var actualTop = parseInt(absolute.css("top"));

        var newTop = Math.max(Math.min(direction + actualTop, 0), maxTop);
        absolute.css("top", newTop + "px");
      }

      /**
       * If buttons not null
       */
      if (settings.scrollButtonUpId && settings.scrollButtonDownId)
      {
        /**
         * Down arrow mouse pressed
         */
        buttonDown.mousedown(function()
        {
          if (timer)
          {
            clearTimeout(timer);
            timer = null;
          }
          timer = setInterval("jQuery.edotScrollBar.scroll(-" + settings.buttonStepPx + ");", settings.scrollbarDelay);
        });
        
        /**
         * Down arrow mouse released
         */
        buttonDown.mouseup(function()
        {
          if (timer)
          {
            clearTimeout(timer);
            timer = null;
          }
        });

        /**
         * Up arrow mouse pressed
         */
        buttonUp.mousedown(function()
        {
          if (timer)
          {
            clearTimeout(timer);
            timer = null;
          }
          timer = setInterval("jQuery.edotScrollBar.scroll(" + settings.buttonStepPx + ");", settings.scrollbarDelay);
        });

        /**
         * Up arrow mouse released
         */
        buttonUp.mouseup(function()
        {
          if (timer)
          {
            clearTimeout(timer);
            timer = null;
          }
        });
        
        /**
         * Mouse leaves down the button
         */
        buttonDown.mouseout(function()
        {
          if (timer)
          {
            clearTimeout(timer);
            timer = null;
          }
        });

        /**
         * Mouse leaves up the button
         */
        buttonUp.mouseout(function()
        {
          if (timer)
          {
            clearTimeout(timer);
            timer = null;
          }
        });
      }

      /**
       * If mousewheel is allowed
       */
      if (settings.mousewheel)
      {
        absolute.mousewheel(function(event, direction)
        {

          jQuery.edotScrollBar.scroll(direction > 0? settings.mouseStepPx : settings.mouseStepPx * (-1));
          return false;
        }, null, true);
      }
    }
  });
})(jQuery);