
;(function( $ ){

	var $scrollTo = $.scrollTo = function( target, duration, settings ){
		$scrollTo.window().scrollTo( target, duration, settings );
	};

	$scrollTo.defaults = {
		axis:'y',
		duration:1
	};

	//returns the element that needs to be animated to scroll the window
	$scrollTo.window = function(){
		return $( $.browser.safari ? 'body' : 'html' );
	};

	$.fn.scrollTo = function( target, duration, settings ){
		if( typeof duration == 'object' ){
			settings = duration;
			duration = 0;
		}
		settings = $.extend( {}, $scrollTo.defaults, settings );
		duration = duration || settings.speed || settings.duration;//speed is still recognized for backwards compatibility
		settings.queue = settings.queue && settings.axis.length > 1;//make sure the settings are given right
		if( settings.queue )
			duration /= 2;//let's keep the overall speed, the same.
		settings.offset = both( settings.offset );
		settings.over = both( settings.over );

		return this.each(function(){
			var elem = this, $elem = $(elem),
				t = target, toff, attr = {},
				win = $elem.is('html,body');
			switch( typeof t ){
				case 'number'://will pass the regex
				case 'string':
					if( /^([+-]=)?\d+(px)?$/.test(t) ){
						t = both( t );
						break;//we are done
					}
					t = $(t,this);// relative selector, no break!
				case 'object':
					if( t.is || t.style )//DOM/jQuery
						toff = (t = $(t)).offset();//get the real position of the target 
			}
			$.each( settings.axis.split(''), function( i, axis ){
				var Pos	= axis == 'x' ? 'Left' : 'Top',
					pos = Pos.toLowerCase(),
					key = 'scroll' + Pos,
					act = elem[key],
					Dim = axis == 'x' ? 'Width' : 'Height',
					dim = Dim.toLowerCase();

				if( toff ){//jQuery/DOM
					attr[key] = toff[pos] + ( win ? 0 : act - $elem.offset()[pos] );

					if( settings.margin ){//if it's a dom element, reduce the margin
						attr[key] -= parseInt(t.css('margin'+Pos)) || 0;
						attr[key] -= parseInt(t.css('border'+Pos+'Width')) || 0;
					}
					
					attr[key] += settings.offset[pos] || 0;//add/deduct the offset
					
					if( settings.over[pos] )//scroll to a fraction of its width/height
						attr[key] += t[dim]() * settings.over[pos];
				}else
					attr[key] = t[pos];//remove the unnecesary 'px'

				if( /^\d+$/.test(attr[key]) )//number or 'number'
					attr[key] = attr[key] <= 0 ? 0 : Math.min( attr[key], max(Dim) );//check the limits

				if( !i && settings.queue ){//queueing each axis is required					
					if( act != attr[key] )//don't waste time animating, if there's no need.
						animate( settings.onAfterFirst );//intermediate animation
					delete attr[key];//don't animate this axis again in the next iteration.
				}
			});			
			animate( settings.onAfter );			

			function animate( callback ){
				$elem.animate( attr, duration, settings.easing, callback && function(){
					callback.call(this, target);
				});
			};
			function max( Dim ){
				var el = win ? $.browser.opera ? document.body : document.documentElement : elem;
				return el['scroll'+Dim] - el['client'+Dim];
			};
		});
	};

	function both( val ){
		return typeof val == 'object' ? val : { top:val, left:val };
	};

})( jQuery );
