var ElementFilter = new Class({

	//implements
	Implements: [Options,Events],

	//options
	options: {
		cache: true,
				caseSensitive: false,
				ignoreKeys: [13, 27, 32, 37, 38, 39, 40],
				matchAnywhere: true,
				property: 'text',
				trigger: 'mouseup',
				onStart: $empty,
				onShow: $empty,
				onHide: $empty,
				onComplete: $empty
	},

	//initialization
	initialize: function(observeElement,elements,options) {
		//set options
				this.setOptions(options);
				//set elements and element
				this.observeElement = document.id(observeElement);
				this.elements = $$(elements);
				this.matches = this.elements;
		this.misses = [];
				//start the listener
				this.listen();
	},

	//adds a listener to the element (if there's a value and if the event code shouldn't be ignored)
	listen: function() {
		//add the requested event
				this.observeElement.addEvent(this.options.trigger,function(e) {
			//if there's a value in the box...
			if(this.observeElement.value.length) {
				//if the key should not be ignored...
				if(!this.options.ignoreKeys.contains(e.code)) {
					this.fireEvent('start');
					this.findMatches(this.options.cache ? this.matches : this.elements);
					this.fireEvent('complete');
				}
			}
			else{
				//show all of the elements
				this.findMatches(this.elements,false);
			}
				}.bind(this));
	},

	//check for matches within specified elements
	findMatches: function(elements,matchOverride) {
		//settings
				var value = this.observeElement.value;
				var regExpPattern = this.options.matchAnywhere ? value : '^' + value;
				var regExpAttrs = this.options.caseSensitive ? '' : 'i';
		var filter = new RegExp(regExpPattern, regExpAttrs);
		var matches = [];				
				//recurse
				elements.each(function(el){
						var match = (matchOverride == undefined ? filter.test(el.get(this.options.property)) : matchOverride);
			//if this element matches, store it...
			if(match) { 
				if(!el.retrieve('showing')){
					this.fireEvent('show',[el]);
				}
				matches.push(el); 
				el.store('showing',true);
			}
			else {
				if(el.retrieve('showing')) {
					this.fireEvent('hide',[el]);
				}
				el.store('showing',false);
			}
			return true;
				}.bind(this));
		return matches;
	}
});