function AutoSuggestControl(oTextbox , 
                            oProvider ) {

    this.cur  = -1;
    this.layer = null;
    this.provider  = oProvider;
    this.textbox  = oTextbox;
    this.timeoutId  = null;
    this.userText  = oTextbox.value;

    this.init();
    
}


AutoSuggestControl.prototype.autosuggest = function (aSuggestions ,
                                                     bTypeAhead ) {
    
    this.cur = -1;

    if (aSuggestions.length > 0) {
        if (bTypeAhead) {
           this.typeAhead(aSuggestions[0]);
        }
        
        this.showSuggestions(aSuggestions);
    } else {
        this.hideSuggestions();
    }
};


AutoSuggestControl.prototype.createDropDown = function () {

    this.layer = document.createElement("div");
    this.layer.className = "suggestions";
    this.layer.style.visibility = "hidden";
    this.layer.style.width = this.textbox.offsetWidth;
    document.body.appendChild(this.layer);    
    
    var oThis = this;
    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();
        }
    };
    
};


AutoSuggestControl.prototype.getLeft = function () /*:int*/ {

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


AutoSuggestControl.prototype.getTop = function (){

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


AutoSuggestControl.prototype.goToSuggestion = function (iDiff /*:int*/) {
    var cSuggestionNodes = this.layer.childNodes;
    
    if (cSuggestionNodes.length > 0) {
        var oNode = null;
    
        if (iDiff > 0) {
            if (this.cur < cSuggestionNodes.length-1) {
                oNode = cSuggestionNodes[++this.cur];
            }        
        } else {
            if (this.cur > 0) {
                oNode = cSuggestionNodes[--this.cur];
            }    
        }
        
        if (oNode) {
            this.highlightSuggestion(oNode);
            this.textbox.value = oNode.firstChild.nodeValue;
        }
    }
};

AutoSuggestControl.prototype.handleKeyDown = function (oEvent /*:Event*/) {

    switch(oEvent.keyCode) {
        case 38: //up arrow
            this.goToSuggestion(-1);
            break;
        case 40: //down arrow 
            this.goToSuggestion(1);
            break;
        case 27: //esc
            this.textbox.value = this.userText;
            this.selectRange(this.userText.length, 0);
            this.hideSuggestions();
            oEvent.returnValue = false;
            if (oEvent.preventDefault) {
                oEvent.preventDefault();
            }
            break;
        case 13: //enter
            this.hideSuggestions();
            oEvent.returnValue = false;
            if (oEvent.preventDefault) {
                oEvent.preventDefault();
            }
            document.searchform.submit();
            //suggestSearch.search(document.getElementById("searchbox").value);
            break;
    }

};


AutoSuggestControl.prototype.handleKeyUp = function (oEvent /*:Event*/) {

    var iKeyCode = oEvent.keyCode;
    var oThis = this;
    
    this.userText = this.textbox.value;
    
    clearTimeout(this.timeoutId);

    if (iKeyCode == 8 || iKeyCode == 46) {
        
        this.timeoutId = setTimeout( function () {
            oThis.provider.requestSuggestions(oThis, false);
        }, 250);
        
    //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.timeoutId = setTimeout( function () {
            oThis.provider.requestSuggestions(oThis, false);
        }, 250);
    }
};


AutoSuggestControl.prototype.hideSuggestions = function () {
    this.layer.style.visibility = "hidden";
};


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 = "";
        }
    }
};


AutoSuggestControl.prototype.init = function () {

    //save a reference to this object
    var oThis = this;
    
    //assign the onkeyup event handler
    this.textbox.onkeyup = function (oEvent) {
        if (!oEvent) {
            oEvent = window.event;
        }    
        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();
};

AutoSuggestControl.prototype.selectRange = function (iStart , iEnd ) {

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

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


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";

};

AutoSuggestControl.prototype.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);
    }
};


function SuggestionProvider() {
    this.http = zXmlHttp.createRequest();
}


SuggestionProvider.prototype.requestSuggestions = function (oAutoSuggestControl, bTypeAhead ) {

    var oHttp = this.http;
                                   
    if (oHttp.readyState != 0) {
        oHttp.abort();
    }                 
    
    //define the data
    var oData = { 
        text: oAutoSuggestControl.userText,
        limit: 15
    };

    oHttp.open("post", "include/suggestions.php", true);
    oHttp.onreadystatechange = function () {
        if (oHttp.readyState == 4) {
            //evaluate the returned text JavaScript (an array)
            var aSuggestions = JSON.parse(oHttp.responseText);

            //provide suggestions to the control
            oAutoSuggestControl.autosuggest(aSuggestions, bTypeAhead);        
        }    
    };
    oHttp.send(JSON.stringify(oData));

};