/**
* An autosuggest textbox control.
* @class
* @scope public
*/
function AutoSuggestControl(oTextbox /*:HTMLInputElement*/, oProvider /*:SuggestionProvider*/) 
{
		
	/**
	* The currently selected suggestions.
	* @scope private
	*/   
	this.cur /*:int*/ = -1;

	/**
	* The dropdown list layer.
	* @scope private
	*/
	this.layer = null;
	
	/**
	* Suggestion provider for the autosuggest feature.
	* @scope private.
	*/
	this.provider /*:SuggestionProvider*/ = oProvider;
	
	/**
	* The textbox to capture.
	* @scope private
	*/
	this.textbox /*:HTMLInputElement*/ = oTextbox;
	
	//initialize the control
	this.init();
	
};

AutoSuggestControl.prototype = {

	/**
	* Autosuggests one or more suggestions for what the user has typed.
	* If no suggestions are passed in, then no autosuggest occurs.
	* @scope private
	* @param aSuggestions An array of suggestion strings.
	* @param bTypeAhead If the control should provide a type ahead suggestion.
	*/
	autosuggest: function (aSuggestions /*:Array*/, bTypeAhead /*:boolean*/) 
	{
		//make sure there's at least one suggestion
		if (aSuggestions.length > 0) {
			if (bTypeAhead) {
			this.typeAhead(aSuggestions[0]);
			}
	        
			this.showSuggestions(aSuggestions);
		} else {
			this.hideSuggestions();
		}
	},

	/**
	* Creates the dropdown layer to display multiple suggestions.
	* @scope private
	*/
	createDropDown: function () 
	{

		var oThis = this;

		//create the layer and assign styles
		this.layer = document.createElement("div");
		this.layer.className = "suggestions";
		this.layer.style.visibility = "hidden";
		this.layer.style.width = this.textbox.offsetWidth - 2;
	    
		//when the user clicks on the a suggestion, get the text (innerHTML)
		//and place it into a textbox
		this.layer.onmousedown = 
		this.layer.onmouseup = 
		this.layer.onmouseover = function (oEvent) {
			oEvent = oEvent || window.event;
			oTarget = oEvent.target || oEvent.srcElement;

			if (oEvent.type == "mousedown") {
				oThis.textbox.value = oTarget.firstChild.nodeValue;
				oThis.hideSuggestions();
			} else if (oEvent.type == "mouseover") {
				oThis.highlightSuggestion(oTarget);
			} else {
				oThis.textbox.focus();
			}
		};
		document.body.appendChild(this.layer);

	},

	/**
	* Gets the left coordinate of the textbox.
	* @scope private
	* @return The left coordinate of the textbox in pixels.
	*/
	getLeft: function () /*:int*/ 
	{

		var oNode = this.textbox;
		var iLeft = 0;

		while(oNode.tagName != "BODY" && oNode.tagName != "HTML") {
			iLeft += oNode.offsetLeft;
			oNode = oNode.offsetParent;
	        
		}
	    
		return iLeft;
	},

	/**
	* Gets the top coordinate of the textbox.
	* @scope private
	* @return The top coordinate of the textbox in pixels.
	*/
	getTop: function () /*:int*/ 
	{

		var oNode = this.textbox;
		var iTop = 0;

		while(oNode.tagName != "BODY" && oNode.tagName != "HTML") {
			iTop += oNode.offsetTop;
			oNode = oNode.offsetParent;
		}

		return iTop;
	},

	/**
	* Handles three keydown events.
	* @scope private
	* @param oEvent The event object for the keydown event.
	*/
	handleKeyDown: function (oEvent /*:Event*/) 
	{
		switch(oEvent.keyCode) {
			case 38: //up arrow
				this.previousSuggestion();
				break;
			case 40: //down arrow 
				this.nextSuggestion();
				break;
			case 13: //enter
				this.hideSuggestionsOrSearch();
				break;
		}
	},

	/**
	* Handles keyup events.
	* @scope private
	* @param oEvent The event object for the keyup event.
	*/
	handleKeyUp: function (oEvent /*:Event*/) 
	{

		var iKeyCode = oEvent.keyCode;

		//for backspace (8) and delete (46), shows suggestions without typeahead
		if (iKeyCode == 8 || iKeyCode == 46) {
			this.provider.requestSuggestions(this, false);
	        
		//make sure not to interfere with non-character keys
		} else if (iKeyCode < 32 || (iKeyCode >= 33 && iKeyCode < 46) || (iKeyCode >= 112 && iKeyCode <= 123)) {
			//ignore
		} else {
			//request suggestions from the suggestion provider with typeahead
			this.provider.requestSuggestions(this, false);
		}
	},

	/**
	* Hides the suggestion dropdown.
	* @scope private
	*/
	hideSuggestions: function () 
	{
		this.layer.style.visibility = "hidden";
	    
	},
	hideSuggestionsOrSearch: function () 
	{
		if(this.layer.style.visibility == "hidden"){
    			goSearch();
		}else{
			this.hideSuggestions();
		}
	},

	/**
	* Highlights the given node in the suggestions dropdown.
	* @scope private
	* @param oSuggestionNode The node representing a suggestion in the dropdown.
	*/
	highlightSuggestion: function (oSuggestionNode) 
	{
	    
		for (var i=0; i < this.layer.childNodes.length; i++) {
			var oNode = this.layer.childNodes[i];
			if (oNode == oSuggestionNode) {
				oNode.className = "current";
			} else if (oNode.className == "current") {
				oNode.className = "";
			}
		}
	},

	/**
	* Initializes the textbox with event handlers for
	* auto suggest functionality.
	* @scope private
	*/
	init: function () 
	{

		//save a reference to this object
		var oThis = this;
	    
		//assign the onkeyup event handler
		this.textbox.onkeyup = function (oEvent) {
	    
			//check for the proper location of the event object
			if (!oEvent) {
				oEvent = window.event;
			}    
	        
			//call the handleKeyUp() method with the event object
			oThis.handleKeyUp(oEvent);        
		};
	    
		//assign onkeydown event handler
		this.textbox.onkeydown = function (oEvent) {
	    
			//check for the proper location of the event object
			if (!oEvent) {
				oEvent = window.event;
			}    
	        
			//call the handleKeyDown() method with the event object
			oThis.handleKeyDown(oEvent);
	        
			//Override .NET _doPostBack onEnter
			if(oEvent.keyCode == 13){
				return false;
			}
		};
	    
		//assign onblur event handler (hides suggestions)    
		this.textbox.onblur = function () {
			oThis.hideSuggestions();
		};
	    
		//create the suggestions dropdown
		this.createDropDown();
	},

	/**
	* Highlights the next suggestion in the dropdown and
	* places the suggestion into the textbox.
	* @scope private
	*/
	nextSuggestion: function () 
	{
		var cSuggestionNodes = this.layer.childNodes;

		if (cSuggestionNodes.length > 0 && this.cur < cSuggestionNodes.length-1) {
			var oNode = cSuggestionNodes[++this.cur];
			this.highlightSuggestion(oNode);
			this.textbox.value = oNode.firstChild.nodeValue; 
		}
	},

	/**
	* Highlights the previous suggestion in the dropdown and
	* places the suggestion into the textbox.
	* @scope private
	*/
	previousSuggestion: function () 
	{
		var cSuggestionNodes = this.layer.childNodes;

		if (cSuggestionNodes.length > 0 && this.cur > 0) {
			var oNode = cSuggestionNodes[--this.cur];
			this.highlightSuggestion(oNode);
			this.textbox.value = oNode.firstChild.nodeValue;   
		}
	},

	/**
	* Selects a range of text in the textbox.
	* @scope public
	* @param iStart The start index (base 0) of the selection.
	* @param iLength The number of characters to select.
	*/
	selectRange: function (iStart /*:int*/, iLength /*:int*/) 
	{

		//use text ranges for Internet Explorer
		if (this.textbox.createTextRange) {
			var oRange = this.textbox.createTextRange(); 
			oRange.moveStart("character", iStart); 
			oRange.moveEnd("character", iLength - this.textbox.value.length);      
			oRange.select();
	        
		//use setSelectionRange() for Mozilla
		} else if (this.textbox.setSelectionRange) {
			this.textbox.setSelectionRange(iStart, iLength);
		}     

		//set focus back to the textbox
		this.textbox.focus();      
	},

	/**
	* Builds the suggestion layer contents, moves it into position,
	* and displays the layer.
	* @scope private
	* @param aSuggestions An array of suggestions for the control.
	*/
	showSuggestions: function (aSuggestions /*:Array*/) 
	{
	    
		var oDiv = null;
		this.layer.innerHTML = "";  //clear contents of the layer
	    
		for (var i=0; i < aSuggestions.length; i++) {
			oDiv = document.createElement("div");
			oDiv.appendChild(document.createTextNode(aSuggestions[i]));
			this.layer.appendChild(oDiv);
		}
	    
		this.layer.style.left = this.getLeft() + "px";
		this.layer.style.top = (this.getTop()+this.textbox.offsetHeight) + "px";
		this.layer.style.visibility = "visible";

	},

	/**
	* Inserts a suggestion into the textbox, highlighting the 
	* suggested part of the text.
	* @scope private
	* @param sSuggestion The suggestion for the textbox.
	*/
	typeAhead: function (sSuggestion /*:String*/) 
	{

		//check for support of typeahead functionality
		if (this.textbox.createTextRange || this.textbox.setSelectionRange){
			var iLen = this.textbox.value.length; 
			this.textbox.value = sSuggestion; 
			this.selectRange(iLen, sSuggestion.length);
		}
	}

}