/**
 * 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();
}

/**
 * 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.
 */
AutoSuggestControl.prototype.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);
		this.cur = -1;
		//this.highlightSuggestion(this.layer.childNodes[0]);
	} else {
		this.hideSuggestions();
	}
};

/**
 * Creates the dropdown layer to display multiple suggestions.
 * @scope private
 */
AutoSuggestControl.prototype.createDropDown = function () {
	var oThis = this;
	//create the layer and assign styles
	this.layer = document.createElement("div");
	this.layer.innerHTML = '<!--[if lte IE 6.5]><iframe class="frm"></iframe><![endif]-->';
	this.layer.className = "suggestions";
	this.layer.id = "suggestions_layer";
	this.layer.style.visibility = "hidden";
	this.layer.style.width = this.textbox.offsetWidth;
	//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.
 */
AutoSuggestControl.prototype.getLeft = function () /*:int*/ {
	var oNode = this.textbox;
	var iLeft = 0;
	while(oNode.tagName != "BODY") {
		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.
 */
AutoSuggestControl.prototype.getTop = function () /*:int*/ {
	var oNode = this.textbox;
	var iTop = 0;
	while(oNode.tagName != "BODY") {
		iTop += oNode.offsetTop;
		oNode = oNode.offsetParent;
	}
	return iTop;
};

/**
 * Handles three keydown events.
 * @scope private
 * @param oEvent The event object for the keydown event.
 */
AutoSuggestControl.prototype.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.hideSuggestions();
		break;
	}
};

/**
 * Handles keyup events.
 * @scope private
 * @param oEvent The event object for the keyup event.
 */
AutoSuggestControl.prototype.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, true);
	}
};

/**
 * Hides the suggestion dropdown.
 * @scope private
 */
AutoSuggestControl.prototype.hideSuggestions = function () {
	this.cur = -1;
	this.layer.style.visibility = "hidden";
};

/**
 * Highlights the given node in the suggestions dropdown.
 * @scope private
 * @param oSuggestionNode The node representing a suggestion in the dropdown.
 */
AutoSuggestControl.prototype.highlightSuggestion = function (oSuggestionNode) {
	for (var i=0; i < this.layer.childNodes.length; i++) {
		var oNode = this.layer.childNodes[i];
		if (oNode.nodeName.toLowerCase()!='iframe') {
			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
 */
AutoSuggestControl.prototype.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);
	};
	//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
 */
AutoSuggestControl.prototype.nextSuggestion = function () {
	var cSuggestionNodes = this.layer.childNodes;
	if (cSuggestionNodes.length > 0) {
		if (++this.cur != cSuggestionNodes.length-1) {
			var oNode = cSuggestionNodes[this.cur];
			this.textbox.value = oNode.firstChild.nodeValue;
			this.highlightSuggestion(oNode);
		} else {
			this.cur = 0;
			this.textbox.value = cSuggestionNodes[0].firstChild.nodeValue;
			this.highlightSuggestion(cSuggestionNodes[0]);
		}
	}
};

/**
 * Highlights the previous suggestion in the dropdown and
 * places the suggestion into the textbox.
 * @scope private
 */
AutoSuggestControl.prototype.previousSuggestion = function () {
	var cSuggestionNodes = this.layer.childNodes;
	if (cSuggestionNodes.length > 0) {
		if (this.cur > 0) {
			var oNode = cSuggestionNodes[--this.cur];
			this.highlightSuggestion(oNode);
			this.textbox.value = oNode.firstChild.nodeValue;
		} else {
			if (!cSuggestionNodes[cSuggestionNodes.length-2].firstChild) {
				alert(cSuggestionNodes[cSuggestionNodes.length-2]);
			}
			this.cur = cSuggestionNodes.length-2;
			this.textbox.value = cSuggestionNodes[cSuggestionNodes.length-2].firstChild.nodeValue;
			this.highlightSuggestion(cSuggestionNodes[cSuggestionNodes.length-2]);
		}
	}
};

/**
 * 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.
 */
AutoSuggestControl.prototype.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.
 */
AutoSuggestControl.prototype.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.innerHTML += '<!--[if lte IE 6.5]><iframe class="frm" style="height:'+this.layer.offsetHeight+'px;"></iframe><![endif]-->';
	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.
 */
AutoSuggestControl.prototype.typeAhead = function (sSuggestion /*:String*/) {
	//check for support of typeahead functionality
	//we don't need to select range - FESTER
	/*if (this.textbox.createTextRange || this.textbox.setSelectionRange){
		var iLen = this.textbox.value.length;
		this.textbox.value = sSuggestion; 
		this.selectRange(iLen, sSuggestion.length);
	}*/
};