// http://www.javascriptsearch.com/articles/alphabetical/n/authors/Nicholas_C__Zakas.html
function RemoteStateSuggestions() {

    if (typeof XMLHttpRequest != "undefined") {
        this.http = new XMLHttpRequest();		// other browsers (such as Mozilla, Safari, and Opera),
    } else if (typeof ActiveXObject != "undefined") {
        this.http = new ActiveXObject("MSXML2.XmlHttp");	//Internet Explorer
    } else {
        //alert("No XMLHttpRequest object available. This functionality will not work.");
    }
}
RemoteStateSuggestions.prototype.requestSuggestions = function (oAutoSuggestControl, bTypeAhead) {
    var oHttp = this.http;		//store XMLHttpRequest object reference (done for convenience and also to work around an issue with Microsoft's implementation)
    if (oHttp.readyState != 0) {	//check to see if a request is already in progress
        oHttp.abort();
    } 
    var sURL = sBaseURL + "/suggestions.html?ui=" + encodeURIComponent(oAutoSuggestControl.textbox.value);
    oHttp.open("get", sURL , true);		// last argument specifies asynchronous request
    oHttp.onreadystatechange = function () {
        if (oHttp.readyState == 4) {	// request has completed when readyState = 4
            var aSuggestions = eval(oHttp.responseText);
            oAutoSuggestControl.autosuggest(aSuggestions, bTypeAhead); 
        } 
    };
    oHttp.send(null);
};
/** An autosuggest textbox control. - @class - @scope public (HTMLInputElement, SuggestionProvider) */
function AutoSuggestControl(oTextbox, oProvider) {

	this.cur = -1;		// The currently selected suggestions. :int 
	this.layer = null;		// The dropdown list layer. 
	this.provider = oProvider;		// Suggestion provider for the autosuggest feature.. 
	this.textbox = oTextbox;	// The textbox to capture. :HTMLInputElement 
	this.init();		// initialize the control
}

/**
 * Autosuggests one or more suggestions for what the user has typed.
 * If no suggestions are passed in, then no autosuggest occurs.
 * @param:array aSuggestions An array of suggestion strings.
 * @param:boolean bTypeAhead If the control should provide a type ahead suggestion.
 */
AutoSuggestControl.prototype.autosuggest = function (aSuggestions, bTypeAhead) {
    
	if (!aSuggestions) {
		//User types too fast or response is too slow - nls 1/29/2009
	}
    //make sure there's at least one suggestion
    else if (aSuggestions.length > 0) {
        if (bTypeAhead) {
           this.typeAhead(aSuggestions[0]);
        }
        this.showSuggestions(aSuggestions);
    } else {
        this.hideSuggestions();
    }
};

// Creates the dropdown layer to display multiple suggestions.
AutoSuggestControl.prototype.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; - disabled nls 1/29/2009
    
    //when the user clicks on 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. @return:int The left coordinate of the textbox in pixels. */
AutoSuggestControl.prototype.getLeft = function () {

    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. @return:int The top coordinate of the textbox in pixels. */
AutoSuggestControl.prototype.getTop = function () {

    var oNode = this.textbox;
    var iTop = 0;
    while(oNode.tagName != "BODY") {
        iTop += oNode.offsetTop;
        oNode = oNode.offsetParent;
    }
    return iTop;
};

/** Handles three keydown events. @param:Event oEvent The event object for the keydown event. */
AutoSuggestControl.prototype.handleKeyDown = function (oEvent) {
    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. @param:Event oEvent The event object for the keyup event. */
AutoSuggestControl.prototype.handleKeyUp = function (oEvent) {

    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 switch (true = yes; false = no)
        this.provider.requestSuggestions(this, false);
    }
};

// Hides the suggestion dropdown.
AutoSuggestControl.prototype.hideSuggestions = function () {
    this.layer.style.visibility = "hidden";
};

// Highlights the given node in the suggestions dropdown. @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 == oSuggestionNode) {
            oNode.className = "current"
        } else if (oNode.className == "current") {
            oNode.className = "";
        }
    }
};

// Initializes the textbox with event handlers for auto suggest functionality.
AutoSuggestControl.prototype.init = function () {

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

// Highlights the next suggestion in the dropdown and places the suggestion into the textbox.
AutoSuggestControl.prototype.nextSuggestion = function () {
    var cSuggestionNodes = this.layer.childNodes;
	// change cSuggestionNodes.length > -1 to 0 if you wish to use typeAhead
    if (cSuggestionNodes.length > -1 && 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.
AutoSuggestControl.prototype.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:int iStart The start index (base 0) of the selection.
 * @param:int iLength The number of characters to select.
 */
AutoSuggestControl.prototype.selectRange = function (iStart, iLength) {

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

/**
 * Builds the suggestion layer contents, moves it into position, and displays the layer.
 * @param:Array aSuggestions An array of suggestions for the control.
 */
AutoSuggestControl.prototype.showSuggestions = function (aSuggestions) {
    
    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.
 * @param:String sSuggestion The suggestion for the textbox.
 */
AutoSuggestControl.prototype.typeAhead = function (sSuggestion) {
    //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);
    }
};