/*
Script: Selectors.js
	Adds advanced CSS Querying capabilities for targeting elements. Also includes pseudoselectors support.

License:
	MIT-style license.
*/

Native.implement([Document, Element], {

	getElements: function(expression, nocash){
		expression = expression.split(',');
		var items, local = {};
		for (var i = 0, l = expression.length; i < l; i++){
			var selector = expression[i], elements = Selectors.Utils.search(this, selector, local);
			if (i != 0 && elements.item) elements = $A(elements);
			items = (i == 0) ? elements : (items.item) ? $A(items).concat(elements) : items.concat(elements);
		}
		return new Elements(items, {ddup: (expression.length > 1), cash: !nocash});
	}

});

Element.implement({

	match: function(selector){
		if (!selector || (selector == this)) return true;
		var tagid = Selectors.Utils.parseTagAndID(selector);
		var tag = tagid[0], id = tagid[1];
		if (!Selectors.Filters.byID(this, id) || !Selectors.Filters.byTag(this, tag)) return false;
		var parsed = Selectors.Utils.parseSelector(selector);
		return (parsed) ? Selectors.Utils.filter(this, parsed, {}) : true;
	}

});

var Selectors = {Cache: {nth: {}, parsed: {}}};

Selectors.RegExps = {
	id: (/#([\w-]+)/),
	tag: (/^(\w+|\*)/),
	quick: (/^(\w+|\*)$/),
	splitter: (/\s*([+>~\s])\s*([a-zA-Z#.*:\[])/g),
	combined: (/\.([\w-]+)|\[(\w+)(?:([!*^$~|]?=)(["']?)([^\4]*?)\4)?\]|:([\w-]+)(?:\(["']?(.*?)?["']?\)|$)/g)
};

Selectors.Utils = {

	chk: function(item, uniques){
		if (!uniques) return true;
		var uid = $uid(item);
		if (!uniques[uid]) return uniques[uid] = true;
		return false;
	},

	parseNthArgument: function(argument){
		if (Selectors.Cache.nth[argument]) return Selectors.Cache.nth[argument];
		var parsed = argument.match(/^([+-]?\d*)?([a-z]+)?([+-]?\d*)?$/);
		if (!parsed) return false;
		var inta = parseInt(parsed[1], 10);
		var a = (inta || inta === 0) ? inta : 1;
		var special = parsed[2] || false;
		var b = parseInt(parsed[3], 10) || 0;
		if (a != 0){
			b--;
			while (b < 1) b += a;
			while (b >= a) b -= a;
		} else {
			a = b;
			special = 'index';
		}
		switch (special){
			case 'n': parsed = {a: a, b: b, special: 'n'}; break;
			case 'odd': parsed = {a: 2, b: 0, special: 'n'}; break;
			case 'even': parsed = {a: 2, b: 1, special: 'n'}; break;
			case 'first': parsed = {a: 0, special: 'index'}; break;
			case 'last': parsed = {special: 'last-child'}; break;
			case 'only': parsed = {special: 'only-child'}; break;
			default: parsed = {a: (a - 1), special: 'index'};
		}

		return Selectors.Cache.nth[argument] = parsed;
	},

	parseSelector: function(selector){
		if (Selectors.Cache.parsed[selector]) return Selectors.Cache.parsed[selector];
		var m, parsed = {classes: [], pseudos: [], attributes: []};
		while ((m = Selectors.RegExps.combined.exec(selector))){
			var cn = m[1], an = m[2], ao = m[3], av = m[5], pn = m[6], pa = m[7];
			if (cn){
				parsed.classes.push(cn);
			} else if (pn){
				var parser = Selectors.Pseudo.get(pn);
				if (parser) parsed.pseudos.push({parser: parser, argument: pa});
				else parsed.attributes.push({name: pn, operator: '=', value: pa});
			} else if (an){
				parsed.attributes.push({name: an, operator: ao, value: av});
			}
		}
		if (!parsed.classes.length) delete parsed.classes;
		if (!parsed.attributes.length) delete parsed.attributes;
		if (!parsed.pseudos.length) delete parsed.pseudos;
		if (!parsed.classes && !parsed.attributes && !parsed.pseudos) parsed = null;
		return Selectors.Cache.parsed[selector] = parsed;
	},

	parseTagAndID: function(selector){
		var tag = selector.match(Selectors.RegExps.tag);
		var id = selector.match(Selectors.RegExps.id);
		return [(tag) ? tag[1] : '*', (id) ? id[1] : false];
	},

	filter: function(item, parsed, local){
		var i;
		if (parsed.classes){
			for (i = parsed.classes.length; i--; i){
				var cn = parsed.classes[i];
				if (!Selectors.Filters.byClass(item, cn)) return false;
			}
		}
		if (parsed.attributes){
			for (i = parsed.attributes.length; i--; i){
				var att = parsed.attributes[i];
				if (!Selectors.Filters.byAttribute(item, att.name, att.operator, att.value)) return false;
			}
		}
		if (parsed.pseudos){
			for (i = parsed.pseudos.length; i--; i){
				var psd = parsed.pseudos[i];
				if (!Selectors.Filters.byPseudo(item, psd.parser, psd.argument, local)) return false;
			}
		}
		return true;
	},

	getByTagAndID: function(ctx, tag, id){
		if (id){
			var item = (ctx.getElementById) ? ctx.getElementById(id, true) : Element.getElementById(ctx, id, true);
			return (item && Selectors.Filters.byTag(item, tag)) ? [item] : [];
		} else {
			return ctx.getElementsByTagName(tag);
		}
	},

	search: function(self, expression, local){
		var splitters = [];

		var selectors = expression.trim().replace(Selectors.RegExps.splitter, function(m0, m1, m2){
			splitters.push(m1);
			return ':)' + m2;
		}).split(':)');

		var items, filtered, item;

		for (var i = 0, l = selectors.length; i < l; i++){

			var selector = selectors[i];

			if (i == 0 && Selectors.RegExps.quick.test(selector)){
				items = self.getElementsByTagName(selector);
				continue;
			}

			var splitter = splitters[i - 1];

			var tagid = Selectors.Utils.parseTagAndID(selector);
			var tag = tagid[0], id = tagid[1];

			if (i == 0){
				items = Selectors.Utils.getByTagAndID(self, tag, id);
			} else {
				var uniques = {}, found = [];
				for (var j = 0, k = items.length; j < k; j++) found = Selectors.Getters[splitter](found, items[j], tag, id, uniques);
				items = found;
			}

			var parsed = Selectors.Utils.parseSelector(selector);

			if (parsed){
				filtered = [];
				for (var m = 0, n = items.length; m < n; m++){
					item = items[m];
					if (Selectors.Utils.filter(item, parsed, local)) filtered.push(item);
				}
				items = filtered;
			}

		}

		return items;

	}

};

Selectors.Getters = {

	' ': function(found, self, tag, id, uniques){
		var items = Selectors.Utils.getByTagAndID(self, tag, id);
		for (var i = 0, l = items.length; i < l; i++){
			var item = items[i];
			if (Selectors.Utils.chk(item, uniques)) found.push(item);
		}
		return found;
	},

	'>': function(found, self, tag, id, uniques){
		var children = Selectors.Utils.getByTagAndID(self, tag, id);
		for (var i = 0, l = children.length; i < l; i++){
			var child = children[i];
			if (child.parentNode == self && Selectors.Utils.chk(child, uniques)) found.push(child);
		}
		return found;
	},

	'+': function(found, self, tag, id, uniques){
		while ((self = self.nextSibling)){
			if (self.nodeType == 1){
				if (Selectors.Utils.chk(self, uniques) && Selectors.Filters.byTag(self, tag) && Selectors.Filters.byID(self, id)) found.push(self);
				break;
			}
		}
		return found;
	},

	'~': function(found, self, tag, id, uniques){
		while ((self = self.nextSibling)){
			if (self.nodeType == 1){
				if (!Selectors.Utils.chk(self, uniques)) break;
				if (Selectors.Filters.byTag(self, tag) && Selectors.Filters.byID(self, id)) found.push(self);
			}
		}
		return found;
	}

};

Selectors.Filters = {

	byTag: function(self, tag){
		return (tag == '*' || (self.tagName && self.tagName.toLowerCase() == tag));
	},

	byID: function(self, id){
		return (!id || (self.id && self.id == id));
	},

	byClass: function(self, klass){
		return (self.className && self.className.contains(klass, ' '));
	},

	byPseudo: function(self, parser, argument, local){
		return parser.call(self, argument, local);
	},

	byAttribute: function(self, name, operator, value){
		var result = Element.prototype.getProperty.call(self, name);
		if (!result) return (operator == '!=');
		if (!operator || value == undefined) return true;
		switch (operator){
			case '=': return (result == value);
			case '*=': return (result.contains(value));
			case '^=': return (result.substr(0, value.length) == value);
			case '$=': return (result.substr(result.length - value.length) == value);
			case '!=': return (result != value);
			case '~=': return result.contains(value, ' ');
			case '|=': return result.contains(value, '-');
		}
		return false;
	}

};

Selectors.Pseudo = new Hash({

	// w3c pseudo selectors

	checked: function(){
		return this.checked;
	},

	empty: function(){
		return !(this.innerText || this.textContent || '').length;
	},

	not: function(selector){
		return !Element.match(this, selector);
	},

	contains: function(text){
		return (this.innerText || this.textContent || '').contains(text);
	},

	'first-child': function(){
		return Selectors.Pseudo.index.call(this, 0);
	},

	'last-child': function(){
		var element = this;
		while ((element = element.nextSibling)){
			if (element.nodeType == 1) return false;
		}
		return true;
	},

	'only-child': function(){
		var prev = this;
		while ((prev = prev.previousSibling)){
			if (prev.nodeType == 1) return false;
		}
		var next = this;
		while ((next = next.nextSibling)){
			if (next.nodeType == 1) return false;
		}
		return true;
	},

	'nth-child': function(argument, local){
		argument = (argument == undefined) ? 'n' : argument;
		var parsed = Selectors.Utils.parseNthArgument(argument);
		if (parsed.special != 'n') return Selectors.Pseudo[parsed.special].call(this, parsed.a, local);
		var count = 0;
		local.positions = local.positions || {};
		var uid = $uid(this);
		if (!local.positions[uid]){
			var self = this;
			while ((self = self.previousSibling)){
				if (self.nodeType != 1) continue;
				count ++;
				var position = local.positions[$uid(self)];
				if (position != undefined){
					count = position + count;
					break;
				}
			}
			local.positions[uid] = count;
		}
		return (local.positions[uid] % parsed.a == parsed.b);
	},

	// custom pseudo selectors

	index: function(index){
		var element = this, count = 0;
		while ((element = element.previousSibling)){
			if (element.nodeType == 1 && ++count > index) return false;
		}
		return (count == index);
	},

	even: function(argument, local){
		return Selectors.Pseudo['nth-child'].call(this, '2n+1', local);
	},

	odd: function(argument, local){
		return Selectors.Pseudo['nth-child'].call(this, '2n', local);
	}

});
