var create = true;
var autoSuggest;

function addAutosuggest(elem){
	var text = elem.value;
	// only add an autosuggest box once we have 3 characters
	if(create && text.length == 3){
		create = false;
		autoSuggest = new AutoSuggest(elem);
	}
}

function createSuggestions(text){
	var puzzleURL = '/puzzletag/suggestajax/?tagName='+text;
	http('GET', puzzleURL, createSuggestionsCallback); 
}
    
function createSuggestionsCallback(obj){ 
	var tags = obj.getElementsByTagName("tag");
	
	// build suggestions
	var suggestions = new Array();
	var count = 0;
	for (var i = 0; i < tags.length; i++) {
    	var suggestion = tags[i].firstChild.data;
        if(suggestion){
        	suggestions[count] = suggestion;
        	count++;
   		}
    }
    autoSuggest.setSuggestions(suggestions);
}

function AutoSuggest(elem)
{

	//The 'me' variable allow you to access the AutoSuggest object
	//from the elem's event handlers defined below.
	var me = this;

	//A reference to the element we're binding the list to.
	this.elem = elem;

	// create suggestions using ajax callback
	this.suggestions;
	var searchString = elem.value;
	createSuggestions(searchString);

	//Arrow to store a subset of eligible suggestions that match the user's input
	this.eligible = new Array();

	//The text input by the user.
	this.inputText = null;

	//A pointer to the index of the highlighted eligible item. -1 means nothing highlighted.
	this.highlighted = -1;

	//A div to use to create the dropdown.
	this.div = document.getElementById("autosuggest");


	//Do you want to remember what keycode means what? Me neither.
	var TAB = 9;
	var ESC = 27;
	var KEYUP = 38;
	var KEYDN = 40;
	

	//The browsers' own autocomplete feature can be problematic, since it will 
	//be making suggestions from the users' past input.
	//Setting this attribute should turn it off.
	elem.setAttribute("autocomplete","off");

	//We need to be able to reference the elem by id. If it doesn't have an id, set one.
	if(!elem.id)
	{
		var id = "autosuggest" + idCounter;
		idCounter++;

		elem.id = id;
	}


	/********************************************************
	onkeydown event handler for the input elem.
	Tab key = use the highlighted suggestion, if there is one.
	Esc key = get rid of the autosuggest dropdown
	Up/down arrows = Move the highlight up and down in the suggestions.
	********************************************************/
	elem.onkeydown = function(ev)
	{
		var key = me.getKeyCode(ev);

		switch(key)
		{
			case TAB:
			me.useSuggestion();
			break;

			case ESC:
			me.hideDiv();
			break;

			case KEYUP:
			if (me.highlighted > 0)
			{
				me.highlighted--;
			}
			me.changeHighlight(key);
			break;

			case KEYDN:
			if (me.highlighted < (me.eligible.length - 1))
			{
				me.highlighted++;
			}
			me.changeHighlight(key);
			break;
		}
	};

	/********************************************************
	onkeyup handler for the elem
	If the text is of sufficient length, and has been changed, 
	then display a list of eligible suggestions.
	********************************************************/
	elem.onkeyup = function(ev) 
	{
		var key = me.getKeyCode(ev);
		switch(key)
		{
		//The control keys were already handled by onkeydown, so do nothing.
		case TAB:
		case ESC:
		case KEYUP:
		case KEYDN:
			return;
		default:
		
			// when to reload the suggestions
			if(searchString != this.value && this.value.length == 3){
				// alert('createSuggestions='+this.value);
				searchString = this.value;
				createSuggestions(searchString);
			}
			
			
			if (this.value != me.inputText && this.value.length >= 1)
			{
				me.inputText = this.value;
				me.getEligible();
				me.createDiv();
				me.positionDiv();
				me.showDiv();
			}
			else
			{
				me.hideDiv();
			}
		}
	};


	/********************************************************
	Insert the highlighted suggestion into the input box, and 
	remove the suggestion dropdown.
	********************************************************/
	this.useSuggestion = function()
	{
		if (this.highlighted > -1)
		{
			this.elem.value = this.eligible[this.highlighted];
			this.hideDiv();
			//It's impossible to cancel the Tab key's default behavior. 
			//So this undoes it by moving the focus back to our field right after
			//the event completes.
			setTimeout("document.getElementById('" + this.elem.id + "').focus()",0);
		}
	};

	/********************************************************
	Display the dropdown. Pretty straightforward.
	********************************************************/
	this.showDiv = function()
	{
		this.div.style.display = 'block';
	};

	/********************************************************
	Hide the dropdown and clear any highlight.
	********************************************************/
	this.hideDiv = function()
	{
		this.div.style.display = 'none';
		this.highlighted = -1;
	};

	/********************************************************
	Modify the HTML in the dropdown to move the highlight.
	********************************************************/
	this.changeHighlight = function()
	{
		var lis = this.div.getElementsByTagName('LI');
		for (i in lis)
		{
			var li = lis[i];

			if (this.highlighted == i)
			{
				li.className = "selected";
			}
			else
			{
				li.className = "";
			}
		}
	};

	/********************************************************
	Position the dropdown div below the input text field.
	********************************************************/
	this.positionDiv = function()
	{
		var el = this.elem;
		var x = 0;
		var y = el.offsetHeight;
	
		//Walk up the DOM and add up all of the offset positions.
		while (el.offsetParent && el.tagName.toUpperCase() != 'BODY')
		{
			x += el.offsetLeft;
			y += el.offsetTop;
			el = el.offsetParent;
		}

		x += el.offsetLeft;
		y += el.offsetTop;

		this.div.style.left = x + 'px';
		this.div.style.top = y + 'px';
	};

	/********************************************************
	Build the HTML for the dropdown div
	********************************************************/
	this.createDiv = function()
	{
		var ul = document.createElement('ul');
	
		//Create an array of LI's for the words.
		for (i in this.eligible)
		{
			var word = this.eligible[i];
	
			var li = document.createElement('li');
			var a = document.createElement('a');
			a.href="javascript:false";
			a.innerHTML = word;
			li.appendChild(a);
	
			if (me.highlighted == i)
			{
				li.className = "selected";
			}
	
			ul.appendChild(li);
		}
	
		this.div.replaceChild(ul,this.div.childNodes[0]);
	

		/********************************************************
		mouseover handler for the dropdown ul
		move the highlighted suggestion with the mouse
		********************************************************/
		ul.onmouseover = function(ev)
		{
			//Walk up from target until you find the LI.
			var target = me.getEventSource(ev);
			while (target.parentNode && target.tagName.toUpperCase() != 'LI')
			{
				target = target.parentNode;
			}
		
			var lis = me.div.getElementsByTagName('LI');
			
	
			for (i in lis)
			{
				var li = lis[i];
				if(li == target)
				{
					me.highlighted = i;
					break;
				}
			}
			me.changeHighlight();
		};

		/********************************************************
		click handler for the dropdown ul
		insert the clicked suggestion into the input
		********************************************************/
		ul.onclick = function(ev)
		{
			me.useSuggestion();
			me.hideDiv();
			me.cancelEvent(ev);
			return false;
		};
	
		this.div.className="suggestion_list";
		this.div.style.position = 'absolute';

	};

	/********************************************************
	determine which of the suggestions matches the input
	********************************************************/
	this.getEligible = function()
	{
		this.eligible = new Array();
		for (i in this.suggestions) 
		{
			var suggestion = this.suggestions[i];
			
			if(suggestion.toLowerCase().indexOf(this.inputText.toLowerCase()) == "0")
			{
				this.eligible[this.eligible.length]=suggestion;
			}
		}
	};

	/********************************************************
	Helper function to determine the keycode pressed in a 
	browser-independent manner.
	********************************************************/
	this.getKeyCode = function(ev)
	{
		if(ev)			//Moz
		{
			return ev.keyCode;
		}
		if(window.event)	//IE
		{
			return window.event.keyCode;
		}
	};

	/********************************************************
	Helper function to determine the event source element in a 
	browser-independent manner.
	********************************************************/
	this.getEventSource = function(ev)
	{
		if(ev)			//Moz
		{
			return ev.target;
		}
	
		if(window.event)	//IE
		{
			return window.event.srcElement;
		}
	};

	/********************************************************
	Helper function to cancel an event in a 
	browser-independent manner.
	(Returning false helps too).
	********************************************************/
	this.cancelEvent = function(ev)
	{
		if(ev)			//Moz
		{
			ev.preventDefault();
			ev.stopPropagation();
		}
		if(window.event)	//IE
		{
			window.event.returnValue = false;
		}
	}
	
	// callback function for suggestions
	this.setSuggestions=function(suggestions){
		this.suggestions = suggestions;
		this.eligible = new Array();
		for (i in this.suggestions) 
		{
			var suggestion = this.suggestions[i];
			
			if(suggestion.toLowerCase().indexOf(this.elem.value.toLowerCase()) == "0")
			{
				this.eligible[this.eligible.length]=suggestion;
			}
		}
		
		me.createDiv();
		me.positionDiv();
		me.showDiv();
	}
	
	this.hide=function(){
		me.hideDiv();
	}
}

//counter to help create unique ID's
var idCounter = 0;