(function($){
    $.widget( "ui.combobox", $.ui.autocomplete, 
        {
        options: { 
            /* override default values here */
            minLength: 2,
            /* the argument to pass to ajax to get the complete list */
            ajaxGetAll: {get: "all"}
        },
        _create: function(){
            if (this.element.is("SELECT")){
                this._selectInit();
                return;
            }
            $.ui.autocomplete.prototype._create.call(this);
            var input = this.element;
            input.addClass( "ui-widget ui-widget-content ui-corner-left" );
            this.button = $( "<button type='button'>&nbsp;</button>" )
            .attr( "tabIndex", -1 )
            .attr( "title", "Show All Items" )
            .insertAfter( input )
            .button({
                icons: { primary: "ui-icon-triangle-1-s" },
                text: false
            })
            .removeClass( "ui-corner-all" )
            .addClass( "ui-corner-right ui-button-icon" )
            .click(function(event) {
                // close if already visible
                if ( input.combobox( "widget" ).is( ":visible" ) ) {
                    input.combobox( "close" );
                    return;
                }
                // when user clicks the show all button, we display the cached full menu
                var data = input.data("combobox");
                clearTimeout( data.closing );
                if (!input.isFullMenu){
                    data._swapMenu();
                    input.isFullMenu = true;
                }
                /* input/select that are initially hidden (display=none, i.e. second level menus), 
                   will not have position cordinates until they are visible. */
                input.combobox( "widget" ).css( "display", "block" )
                .position($.extend({ of: input },
                    data.options.position
                    ));
                input.focus();
                data._trigger( "open" );
            });
            /* to better handle large lists, put in a queue and process sequentially */
            $(document).queue(function(){
                var data = input.data("combobox");
                if ($.isArray(data.options.source)){ 
                    $.ui.combobox.prototype._renderFullMenu.call(data, data.options.source);
                }else if (typeof data.options.source === "string") {
                    $.getJSON(data.options.source, data.options.ajaxGetAll , function(source){
                        $.ui.combobox.prototype._renderFullMenu.call(data, source);
                    });
                }else {
                    $.ui.combobox.prototype._renderFullMenu.call(data, data.source());
                }
            });
        },
        /* initialize the full list of items, this menu will be reused whenever the user clicks the show all button */
        _renderFullMenu: function(source){
            var self = this,
                input = this.element,
                ul = input.data( "combobox" ).menu.element,
                lis = [];
            source = this._normalize(source); 
            var ulClassIdentificator;
            if (typeof this.options.selectElement.attr('id') != 'undefined') {
                ulClassIdentificator = this.options.selectElement.attr('id');
            } else if (typeof this.options.selectElement.attr('name') != 'undefined') {
                ulClassIdentificator = this.options.selectElement.attr('name');
            }
            if (ulClassIdentificator) {
                ulClassIdentificator = 'ui-autocomplete-menu-' + ulClassIdentificator;
                if (!ul.hasClass(ulClassIdentificator)) {
                    ul.addClass(ulClassIdentificator);
                }
            }
            input.data( "combobox" ).menuAll = input.data( "combobox" ).menu.element.clone(true).appendTo("body");
            for(var i=0; i<source.length; i++){
                lis[i] = "<li class=\"ui-menu-item\" role=\"menuitem\"><a class=\"ui-corner-all\" tabindex=\"-1\">"+source[i].label+"</a></li>";
            }
            ul.append(lis.join(""));
            this._resizeMenu();
            // setup the rest of the data, and event stuff
            setTimeout(function(){
                self._setupMenuItem.call(self, ul.children("li"), source );
            }, 0);
            input.isFullMenu = true;
        },
        /* incrementally setup the menu items, so the browser can remains responsive when processing thousands of items */
        _setupMenuItem: function( items, source ){
            var self = this,
                itemsChunk = items.splice(0, 500),
                sourceChunk = source.splice(0, 500);
            for(var i=0; i<itemsChunk.length; i++){
                $(itemsChunk[i])
                .data( "item.autocomplete", sourceChunk[i])
                .mouseenter(function( event ) {
                    self.menu.activate( event, $(this));
                })
                .mouseleave(function() {
                    self.menu.deactivate();
                });
            }
            if (items.length > 0){
                setTimeout(function(){
                    self._setupMenuItem.call(self, items, source );
                }, 0);
            }else { // renderFullMenu for the next combobox.
                $(document).dequeue();
            }
        },
        /* overwrite. make the matching string bold */
        _renderItem: function( ul, item ) {
            var label = item.label.replace( new RegExp(
                "(?![^&;]+;)(?!<[^<>]*)(" + $.ui.autocomplete.escapeRegex(this.term) + 
                ")(?![^<>]*>)(?![^&;]+;)", "gi"), "<strong>$1</strong>" );
            return $( "<li></li>" )
                .data( "item.autocomplete", item )
                .append( "<a>" + label + "</a>" )
                .appendTo( ul );
        },
        /* overwrite. to cleanup additional stuff that was added */
        destroy: function() {
            if (this.element.is("SELECT")){
                this.input.remove();
                this.element.removeData().show();
                return;
            }
            $.ui.autocomplete.prototype.destroy.call(this);
            // clean up new stuff
            this.element.removeClass( "ui-widget ui-widget-content ui-corner-left" );
            this.button.remove();
        },
        /* overwrite. to swap out and preserve the full menu */ 
        search: function( value, event){
            var input = this.element;
            if (input.isFullMenu){
                this._swapMenu();
                input.isFullMenu = false;
            }
            $.ui.autocomplete.prototype.search.call(this, value, event);
        },
        _change: function( event ){
            abc = this;
            if ( !this.selectedItem ) {
                var matcher = new RegExp( "^" + $.ui.autocomplete.escapeRegex( this.element.val() ) + "$", "i" ),
                    match = $.grep( this.options.source, function(value) {
                        return matcher.test( value.label );
                    });
                if (match.length){
                    match[0].option.selected = true;
                }else {
                    // remove invalid value, as it didn't match anything
                    this.element.val( "" );
                    if (this.options.selectElement) {
                        this.options.selectElement.val( "" );
                    }
                }
            }                
            $.ui.autocomplete.prototype._change.call(this, event);
        },
        _swapMenu: function(){
            var input = this.element, 
                data = input.data("combobox"),
                tmp = data.menuAll;
            data.menuAll = data.menu.element.hide();
            data.menu.element = tmp;
        },
        /* build the source array from the options of the select element */
        _selectInit: function(){
            var select = this.element.hide(),
            selected = select.children( ":selected" ),
            value = selected.val() ? selected.text() : "";
            this.options.source = select.children( "option[value!='']" ).map(function() {
                return { label: $.trim(this.text), option: this };
            }).toArray();
            var userSelectCallback = this.options.select;
            var userSelectedCallback = this.options.selected;
            this.options.select = function(event, ui){
                ui.item.option.selected = true;
                if (userSelectCallback) userSelectCallback(event, ui);
                // compatibility with jQuery UI's combobox.
                if (userSelectedCallback) userSelectedCallback(event, ui);
            };
            this.options.selectElement = select;
            this.input = $( "<input>" ).insertAfter( select )
                .val( value ).combobox(this.options);
        }
    }
);
})(jQuery);