/*
* Example: jQuery('#menu').float({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
*/
$.fn.floatbox=function(options, lockBottom) {
    var $obj 				= this;
    var $par=$('body');
    var parentPaddingTop 	= parseInt($par.css('padding-top'));
    var startOffset 		= $par.offset().top;
    var opts 			= $.extend({ startOffset: startOffset, offsetY: parentPaddingTop, duration: 200, lockBottom:true, right:'20px' }, options);

    $obj.css({ position: 'absolute', display:'block', top: startOffset, right: opts.right });

    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 );
            }
    });
};