/*
 * stickyfloat - jQuery plugin for verticaly floating anything in a constrained area
 * 
 * Example: jQuery('#menu').stickyfloat({duration: 400});
 * parameters:
 *      duration    - the duration of the animation
 *      startOffset - the amount of scroll offset after it the animations kicks in
 *      offsetY     - the offset from the top when the object is animated
 *      lockBottom  - 'true' by default, set to false if you don't want your floating box to stop at parent's bottom
 * $Version: 05.16.2009 r1
 * Copyright (c) 2009 Yair Even-Or
 * vsync.design@gmail.com
 */

$.fn.stickyfloat = function(options, lockBottom) {
    var $obj                = this;
    var parentPaddingTop    = parseInt($obj.parent().css('padding-top'));
    var startOffset         = $obj.parent().offset().top;
    var opts                = $.extend({ startOffset: startOffset, offsetY: parentPaddingTop+25, duration: 400, lockBottom:true }, options);
    
    $obj.css({ position: 'absolute' });
    
    if(opts.lockBottom){
        var bottomPos = $obj.parent().height() - $obj.height() + parentPaddingTop; //get the maximum scrollTop value
        if( bottomPos < 0 )
            bottomPos = 0;
    }
    
    $(window).scroll(function () { 
        $obj.stop(); // stop all calculations on scroll event

        var pastStartOffset         = $(document).scrollTop() > opts.startOffset;   // check if the window was scrolled down more than the start offset declared.
        var objFartherThanTopPos    = $obj.offset().top > startOffset;  // check if the object is at it's top position (starting point)
        var objBiggerThanWindow     = $obj.outerHeight() < $(window).height();  // if the window size is smaller than the Obj size, then do not animate.
        
        // if window scrolled down more than startOffset OR obj position is greater than
        // the top position possible (+ offsetY) AND window size must be bigger than Obj size
        if( (pastStartOffset || objFartherThanTopPos) && objBiggerThanWindow ){ 
            var newpos = ($(document).scrollTop() -startOffset + opts.offsetY );
            if ( newpos > bottomPos )
                newpos = bottomPos;
            if ( $(document).scrollTop() < opts.startOffset ) // if window scrolled < starting offset, then reset Obj position (opts.offsetY);
                newpos = parentPaddingTop;

            $obj.animate({ top: newpos }, opts.duration );
        }
    });
};
$('#sidebar').stickyfloat({ duration: 300 });