$(function() {
  $.widget("custom.combobox", {
    _create: function() {
      this.wrapper = $("<span>").addClass("custom-combobox").insertAfter(this.element);
      this.element.hide();
      this._createAutocomplete();
      this._createShowAllButton();
    },
    _createAutocomplete: function() {
      var selected = this.element.children(":selected"),
          value = selected.val() ? selected.text() : "All";
 
      this.input = $("<input>").appendTo( this.wrapper ).val( value ).attr( "title", "" ).addClass( "custom-combobox-input ui-widget ui-widget-content ui-state-default ui-corner-left" ).autocomplete({
        delay: 0,
        minLength: 0,
        source: $.proxy(this, "_source")
        }).tooltip({tooltipClass: "ui-state-highlight"});

      this._on( this.input, {
        autocompleteselect: function( event, ui ) {
          ui.item.option.selected = true;
          this._trigger( "select", event, {
            item: ui.item.option
          });
        },
        autocompletechange: "_removeIfInvalid"
      });
    },
    _createShowAllButton: function() {
      var input = this.input,
          wasOpen = false;
 
      $('<a>').attr("tabIndex", -1).attr("title", "Show All Items").tooltip().appendTo(this.wrapper).button({icons:{primary:"ui-icon-triangle-1-s"}, text: false}).removeClass("ui-corner-all")
          .addClass( "custom-combobox-toggle ui-corner-right" )
          .mousedown(function() {
            wasOpen = input.autocomplete( "widget" ).is( ":visible" );
          })
          .click(function() {
            input.focus();
 
            // Close if already visible
            if ( wasOpen ) {
              return;
            }
            
            // Pass empty string as value to search for, displaying all results
            input.autocomplete("search", "");
          });
      },
      _source: function(request, response) {
        var matcher = new RegExp($.ui.autocomplete.escapeRegex(request.term), "i");
        response( this.element.children( "option" ).map(function() {
          var text = $( this ).text();
          if ( this.value && ( !request.term || matcher.test(text) ) )
            return {
              label: text,
              value: text,
              option: this
            };
        }));
      },
 
      _removeIfInvalid: function( event, ui ) {
 
        // Selected an item, nothing to do
        if ( ui.item ) {
          return;
        }
 
        // Search for a match (case-insensitive)
        var value = this.input.val(),
          valueLowerCase = value.toLowerCase(),
          valid = false;
        this.element.children( "option" ).each(function() {
          if ( $( this ).text().toLowerCase() === valueLowerCase ) {
            this.selected = valid = true;
            return false;
          }
        });
 
        // Found a match, nothing to do
        if ( valid ) {
          return;
        }
 
        // Remove invalid value
        this.input
          .val( "" )
          .attr( "title", value + " didn't match any item" )
          .tooltip( "open" );
        this.element.val( "" );
        this._delay(function() {
          this.input.tooltip( "close" ).attr( "title", "" );
        }, 2500 );
        this.input.autocomplete( "instance" ).term = "";
      },
 
      _destroy: function() {
        this.wrapper.remove();
        this.element.show();
      }
  });
});