/**
 * jQuery.ScrollTo
 * Copyright (c) 2008 Ariel Flesler - aflesler(at)gmail(dot)com | http://flesler.blogspot.com
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 * Date: 2/19/2008
 *
 * @projectDescription Easy element scrolling using jQuery.
 * Tested with jQuery 1.2.1. On FF 2.0.0.11, IE 6, Opera 9.22 and Safari 3 beta. on Windows.
 *
 * @author Ariel Flesler
 * @version 1.3.3
 *
 * @id jQuery.scrollTo
 * @id jQuery.fn.scrollTo
 * @param {String, Number, DOMElement, jQuery, Object} target Where to scroll the matched elements.
 *	  The different options for target are:
 *		- A number position (will be applied to all axes).
 *		- A string position ('44', '100px', '+=90', etc ) will be applied to all axes
 *		- A jQuery/DOM element ( logically, child of the element to scroll )
 *		- A string selector, that will be relative to the element to scroll ( 'li:eq(2)', etc )
 *		- A hash { top:x, left:y }, x and y can be any kind of number/string like above.
 * @param {Number} duration The OVERALL length of the animation, this argument can be the settings object instead.
 * @param {Object} settings Hash of settings, optional.
 *	 @option {String} axis Which axis must be scrolled, use 'x', 'y', 'xy' or 'yx'.
 *	 @option {Number} duration The OVERALL length of the animation.
 *	 @option {String} easing The easing method for the animation.
 *	 @option {Boolean} margin If true, the margin of the target element will be deducted from the final position.
 *	 @option {Object, Number} offset Add/deduct from the end position. One number for both axes or { top:x, left:y }.
 *	 @option {Object, Number} over Add/deduct the height/width multiplied by 'over', can be { top:x, left:y } when using both axes.
 *	 @option {Boolean} queue If true, and both axis are given, the 2nd axis will only be animated after the first one ends.
 *	 @option {Function} onAfter Function to be called after the scrolling ends. 
 *	 @option {Function} onAfterFirst If queuing is activated, this function will be called after the first scrolling ends.
 * @return {jQuery} Returns the same jQuery object, for chaining.
 *
 * @example $('div').scrollTo( 340 );
 *
 * @example $('div').scrollTo( '+=340px', { axis:'y' } );
 *
 * @example $('div').scrollTo( 'p.paragraph:eq(2)', 500, { easing:'swing', queue:true, axis:'xy' } );
 *
 * @example var second_child = document.getElementById('container').firstChild.nextSibling;
 *			$('#container').scrollTo( second_child, { duration:500, axis:'x', onAfter:function(){
 *				alert('scrolled!!');																   
 *			}});
 *
 * @example $('div').scrollTo( { top: 300, left:'+=200' }, { offset:-20 } );
 *
 * Notes:
 *  - jQuery.scrollTo will make the whole window scroll, it accepts the same arguments as jQuery.fn.scrollTo.
 *	- If you are interested in animated anchor navigation, check http://jquery.com/plugins/project/LocalScroll.
 *	- The options margin, offset and over are ignored, if the target is not a jQuery object or a DOM element.
 *	- The option 'queue' won't be taken into account, if only 1 axis is given.
 */
;(function( $ ){

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

	$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, index_old, index_new ){
		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, index_old, index_new );//intermediate animation
					delete attr[key];//don't animate this axis again in the next iteration.
				}
			});		
			animate( settings.onAfter, index_old, index_new );


			// Massive hacks!
			// And yet somehow appropriate
			function animate( callback, index_old, index_new ){
				var steps = 0;
				var pos_a, pos_b, newbgpos;
				var singlebg = false;
				var dir = "none";
				var nav_loc = $('#nav');
				
				if( (index_old || index_new) == undefined ) {
					index_old = $('body').attr('io');
					index_new = $('body').attr('in');
				}
				$('body').attr('io', index_old).attr('in', index_new);
				
				if( index_old < index_new )
					dir = "ltr";
				else if ( index_old > index_new )
					dir = "rtl";
				
				// Get written style attribute (only way to get multiple positions)
				//var bgpos = nav_loc.css('background-position')
				var bgpos = nav_loc.backgroundPosition();
				
				// Edit string to remove fluff
				bgpos = bgpos.replace(',','').replace(';','').replace('px','').replace('px','').replace('px','').replace('%','');
				bgpos = bgpos.split(' ');
				
				//console.log(bgpos.length);
				if(  bgpos.length <= 2 ) {
					//console.log('?');
					singlebg = true; }
				
				//bgpos[0] = bgpos
				
				$elem.animate(
					attr,
					{
						'duration': duration,
						'easing':	settings.easing,
						complete: function(){	
							callback.call(this, target);
						},
						step: function(a,b) {
							// Additional scrolling image effect
							if( dir != "none") {
								if( dir == "ltr" ) {
									pos_a = parseInt(bgpos[0]) - (5 * steps); // front crowd
									pos_b = parseInt(bgpos[2]) - (2 * steps); // back crowd
								} else if( dir == "rtl" ) {
									pos_a = parseInt(bgpos[0]) + (5 * steps); // front crowd
									pos_b = parseInt(bgpos[2]) + (2 * steps); // back crowd
								}
								
								if( !singlebg ) {
									newbgpos = pos_a + "% 50px, " + pos_b + "px 0!important;";
									nav_loc.css('background-position', newbgpos);
									//nav_loc.attr('style', "background-position: " + newbgpos);
								}
							}
							
							steps = steps + 1;
						}
					}
				);
			}
			
			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 );