/*
 * jQuery UI Position @VERSION
 *
 * Copyright (c) 2009 AUTHORS.txt (http://jqueryui.com/about)
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 *
 * TODO: create document page for position and add link here
 */
(function($) {

var horizontalPositions = /left|center|right/,
	horizontalDefault = 'center',
	verticalPositions = /top|center|bottom/,
	verticalDefault = 'center',
	_position = $.fn.position;

$.fn.position = function(options) {    
	if (!options || !options.of) {
		return _position.apply(this, arguments);
	}

	options = $.extend({
		stackFix: true
	}, options);

	var target = $(options.of),
		collision = (options.collision || 'flip').split(' '),
		offset = options.offset ? options.offset.split(' ') : [0, 0],
		targetWidth,
		targetHeight,
		basePosition;

	if (options.of == document) {
		targetWidth = target.width();
		targetHeight = target.height();
		basePosition = { top: 0, left: 0 };
	} else if (options.of == window) {
		targetWidth = target.width();
		targetHeight = target.height();
		basePosition = { top: target.scrollTop(), left: target.scrollLeft() };
	} else if (options.of.preventDefault) {
		targetWidth = targetHeight = 0;
		basePosition = { top: options.of.pageY, left: options.of.pageX };
	} else {
		targetWidth = target.outerWidth();
		targetHeight = target.outerHeight();
		basePosition = target.offset();
	}

	// force my and at to have valid horizontal and veritcal positions
	// if a value is missing or invalid, it will be converted to center 
	$.each(['my', 'at'], function() {
		var pos = options[this].split(' ');
		pos = pos.length == 1
			? horizontalPositions.test(pos[0])
				? pos.concat([verticalDefault])
				: verticalPositions.test(pos[0])
					? [horizontalDefault].concat(pos)
					: [horizontalDefault, verticalDefault]
			: pos;
		pos[0] = horizontalPositions.test(pos[0]) ? pos[0] : horizontalDefault;
		pos[1] = verticalPositions.test(pos[1]) ? pos[1] : verticalDefault;
        
		options[this] = pos;
	});

	// normalize collision option
	if (collision.length == 1) {
		collision[1] = collision[0];
	}

	// normalize offset option
	offset[0] = parseInt(offset[0], 10) || 0;
	if (offset.length == 1) {
		offset[1] = offset[0];
	}
	offset[1] = parseInt(offset[1], 10) || 0;

	switch (options.at[0]) {
		case 'right':
			basePosition.left += targetWidth;
			break;
		case horizontalDefault:
			basePosition.left += targetWidth / 2;
			break;
	}

	switch (options.at[1]) {
		case 'bottom':
			basePosition.top += targetHeight;
			break;
		case verticalDefault:
			basePosition.top += targetHeight / 2;
			break;
	}

	basePosition.left += offset[0];
	basePosition.top += offset[1];

	return this.each(function() {
		var elem = $(this),
			elemWidth = elem.outerWidth(),
			elemHeight = elem.outerHeight(),
			position = $.extend({}, basePosition),
			over,
			myOffset,
			atOffset;

		switch (options.my[0]) {
			case 'right':
				position.left -= elemWidth;
				break;
			case horizontalDefault:
				position.left -= elemWidth / 2;
				break;
		}

		switch (options.my[1]) {
			case 'bottom':
				position.top -= elemHeight;
				break;
			case verticalDefault:
				position.top -= elemHeight / 2;
				break;
		}

		$.each(['left', 'top'], function(i, dir) {
			($.ui.position[collision[i]] &&
				$.ui.position[collision[i]][dir](position, {
					targetWidth: targetWidth,
					targetHeight: targetHeight,
					elemWidth: elemWidth,
					elemHeight: elemHeight,
					offset: offset,
					my: options.my,
					at: options.at
				}));
		});

		(options.stackfix && $.fn.stackfix && elem.stackfix());
		// the by function is passed the offset values, not the position values
		// we'll need the logic from the .offset() setter to be accessible for
		// us to calculate the position values to make the by option more useful
		($.isFunction(options.by) ? options.by.call(this, position) : elem.offset(position));
	});
};

$.ui.position = {
	fit: {
		left: function(position, data) {
			var over = position.left + data.elemWidth - $(window).width() - $(window).scrollLeft();
			position.left = over > 0 ? position.left - over : Math.max(0, position.left);
		},
		top: function(position, data) {
			var over = position.top + data.elemHeight - $(window).height() - $(window).scrollTop();
			position.top = over > 0 ? position.top - over : Math.max(0, position.top);
		}
	},

	flip: {
		left: function(position, data) {
			var over = position.left + data.elemWidth - $(window).width() - $(window).scrollLeft(),
				myOffset = data.my[0] == 'left' ? -data.elemWidth : data.elemWidth,
				offset = -2 * data.offset[0];
			position.left += position.left < 0 ? myOffset + data.targetWidth + offset : over > 0 ? myOffset - data.targetWidth + offset : 0;
		},
		top: function(position, data) {
			var over = position.top + data.elemHeight - $(window).height() - $(window).scrollTop(),
				myOffset = data.my[1] == 'top' ? -data.elemHeight : data.elemHeight,
				atOffset = data.at[1] == 'top' ? data.targetHeight : -data.targetHeight,
				offset = -2 * data.offset[1];
			position.top += position.top < 0 ? myOffset + data.targetHeight + offset : over > 0 ? myOffset + atOffset + offset : 0;
		}
	}
};


// the following functionality is planned for jQuery 1.4
// copied from http://plugins.jquery.com/files/offset.js.txt
$.fn.extend({

	/**
	 * Stores the original version of offset(), so that we don't lose it
	 */
	_offset : $.fn.offset,
	
	/**
	 * Set or get the specific left and top position of the matched
	 * elements, relative the the browser window by calling setXY
	 * @param {Object} newOffset
	 */
	offset : function(newOffset){
	    return !newOffset ? this._offset() : this.each(function(){
			var el = this;
			
			var hide = false;
			
			if($(el).css('display')=='none'){
				hide = true;
				$(el).show();
			};
			
			var style_pos = $(el).css('position');
			
			// default to relative
			if (style_pos == 'static') {
				$(el).css('position','relative');
				style_pos = 'relative';
			};
			
			var offset = $(el).offset();
			
			if (offset){
				var delta = {
					left : parseInt($(el).css('left'), 10),
					top: parseInt($(el).css('top'), 10)
				};
				
				// in case of 'auto'
				if (isNaN(delta.left)) 
					delta.left = (style_pos == 'relative') ? 0 : el.offsetLeft;
				if (isNaN(delta.top))
					delta.top = (style_pos == 'relative') ? 0 : el.offsetTop;
				
				if (newOffset.left || newOffset.left===0)
					$(el).css('left',newOffset.left - offset.left + delta.left + 'px');
			
				if (newOffset.top || newOffset.top===0)
					$(el).css('top',newOffset.top - offset.top + delta.top + 'px');
			};
			if(hide) $(el).hide();
		});
	}

});

})(jQuery);