function ListFacet(div, config, options, selection) {
    this._div = div;
    this._config = config;
    
    this._options = options || {};
    if (!("sort" in this._options)) {
        this._options.sort = "name";
    }
    
    this._selection = selection || [];
    this._blankChoice = null;
    this._errorChoice = null;
    
    this._data = null;
    
    this.render();
}

ListFacet.reconstruct = function(div, uiState) {
    return new ListFacet(div, uiState.c, uiState.o, uiState.s);
};

ListFacet.prototype.getUIState = function() {
    var json = {
        c: this.getJSON(),
        o: this._options
    };
    
    json.s = json.c.selection;
    delete json.c.selection;
    
    return json;
}

ListFacet.prototype.getJSON = function() {
    var o = {
        type: "list",
        name: this._config.name,
        columnName: this._config.columnName,
        expression: this._config.expression,
        selection: [],
        selectBlank: this._blankChoice != null && this._blankChoice.s,
        selectError: this._errorChoice != null && this._errorChoice.s
    }
    for (var i = 0; i < this._selection.length; i++) {
        var choice = {
            v: cloneDeep(this._selection[i].v)
        };
        o.selection.push(choice);
    }
    return o;
};

ListFacet.prototype.hasSelection = function() {
    return this._selection.length > 0 || 
        (this._blankChoice != null && this._blankChoice.s) || 
        (this._errorChoice != null && this._errorChoice.s);
};

ListFacet.prototype.updateState = function(data) {
    this._data = data;
    
    var selection = [];
    var choices = data.choices;
    for (var i = 0; i < choices.length; i++) {
        var choice = choices[i];
        if (choice.s) {
            selection.push(choice);
        }
    }
    this._selection = selection;
    this._reSortChoices();
    
    this._blankChoice = data.blankChoice || null;
    this._errorChoice = data.errorChoice || null;
    
    this.render();
};

ListFacet.prototype._reSortChoices = function() {
    this._data.choices.sort(this._options.sort == "name" ?
        function(a, b) {
            return a.v.l.localeCompare(b.v.l);
        } :
        function(a, b) {
            return b.c - a.c;
        }
    );
};

ListFacet.prototype.render = function() {
    var self = this;
    
    var scrollTop = 0;
    try {
        scrollTop = this._div[0].childNodes[1].scrollTop;
    } catch (e) {
    }
    var container = this._div.empty();
    
    var headerDiv = $('<div></div>').addClass("facet-title").appendTo(container);
    $('<span></span>').text(this._config.name).appendTo(headerDiv);
    
    var removeButton = $('<img>')
        .attr("src", "images/close.png")
        .attr("title", "Remove this facet")
        .addClass("facet-choice-link")
        .click(function() {
            self._remove();
        }).prependTo(headerDiv);
    
    var bodyDiv = $('<div></div>').addClass("facet-body");
    if (!("scroll" in this._options) || this._options.scroll) {
        bodyDiv.addClass("facet-body-scrollable");
    }
    
    if (this._data == null) {
        bodyDiv.appendTo(container);
        bodyDiv.html("Loading...");
    } else {
        var selectionCount = this._selection.length
            + (this._blankChoice != null && this._blankChoice.s ? 1 : 0)
            + (this._errorChoice != null && this._errorChoice.s ? 1 : 0);
            
        if (selectionCount > 0) {
            var reset = function() {
                self._reset();
            };
            removeButton.after(
                $('<a href="javascript:{}"></a>').addClass("facet-choice-link").text("reset").click(reset)
            );
        }
        
        var renderChoice = function(choice, customLabel) {
            var label = customLabel || choice.v.l;
            var count = choice.c;
            
            var choiceDiv = $('<div></div>').addClass("facet-choice").appendTo(bodyDiv);
            if (choice.s) {
                choiceDiv.addClass("facet-choice-selected");
            }
            
            var a = $('<a href="javascript:{}"></a>').addClass("facet-choice-label").text(label).appendTo(choiceDiv);
            $('<span></span>').addClass("facet-choice-count").text(count).appendTo(choiceDiv);
            
            var select = function() {
                self._select(choice, false);
            };
            var selectOnly = function() {
                self._select(choice, true);
            };
            var deselect = function() {
                self._deselect(choice);
            };
            
            if (choice.s) { // selected
                if (selectionCount > 1) {
                    // select only
                    a.click(selectOnly);
                } else {
                    // deselect
                    a.click(deselect);
                }
                
                // remove link
                $('<a href="javascript:{}"></a>').addClass("facet-choice-link").text("remove").click(deselect).prependTo(choiceDiv);
            } else if (selectionCount > 0) {
                a.click(selectOnly);
                
                // include link
                $('<a href="javascript:{}"></a>').addClass("facet-choice-link").text("include").click(select).appendTo(choiceDiv);
            } else {
                a.click(select);
            }
            
        };
        
        var choices = this._data.choices;
        for (var i = 0; i < choices.length; i++) {
            renderChoice(choices[i]);
        }
        if (this._blankChoice != null) {
            renderChoice(this._blankChoice, "(blank)");
        }
        if (this._errorChoice != null) {
            renderChoice(this._errorChoice, "(error)");
        }
        
        bodyDiv.appendTo(container);
        bodyDiv[0].scrollTop = scrollTop;
        
        var footerDiv = $('<div></div>').addClass("facet-footer").appendTo(container);
        
        $('<span>').text(choices.length + " choices: ").appendTo(footerDiv);
        if (this._options.sort == "name") {
            $('<a href="javascript:{}"></a>').addClass("action").text("re-sort by count").click(function() {
                self._options.sort = "count";
                self._reSortChoices();
                self.render();
            }).appendTo(footerDiv);
        } else {
            $('<a href="javascript:{}"></a>').addClass("action").text("re-sort by name").click(function() {
                self._options.sort = "name";
                self._reSortChoices();
                self.render();
            }).appendTo(footerDiv);
        }
        
        $('<span>').html(" &bull; ").appendTo(footerDiv);
        $('<a href="javascript:{}"></a>').addClass("action").text("edit").click(function() {
            self._doEdit();
        }).appendTo(footerDiv);
    }
};

ListFacet.prototype._doEdit = function() {
    var entries = [];
    for (var i = 0; i < this._data.choices.length; i++) {
        var choice = this._data.choices[i];
        entries.push({
            v: choice.v,
            c: choice.c
        });
    }
    new FacetBasedEditDialog(this._config.columnName, this._config.expression, entries);
};

ListFacet.prototype._select = function(choice, only) {
    if (only) {
        this._selection = [];
        if (this._blankChoice != null) {
            this._blankChoice.s = false;
        }
        if (this._errorChoice != null) {
            this._errorChoice.s = false;
        }
    }
    
    choice.s = true;
    if (choice !== this._errorChoice && choice !== this._blankChoice) {
        this._selection.push(choice);
    }
    
    this._updateRest();
};

ListFacet.prototype._deselect = function(choice) {
    if (choice === this._errorChoice || choice === this._blankChoice) {
        choice.s = false;
    } else {
        for (var i = this._selection.length - 1; i >= 0; i--) {
            if (this._selection[i] === choice) {
                this._selection.splice(i, 1);
                break;
            }
        }
    }
    this._updateRest();
};

ListFacet.prototype._reset = function() {
    this._selection = [];
    this._blankChoice = null;
    this._errorChoice = null;
    
    this._updateRest();
};

ListFacet.prototype._remove = function() {
    ui.browsingEngine.removeFacet(this);
    
    this._div = null;
    this._config = null;
    
    this._selection = null;
    this._blankChoice = null;
    this._errorChoice = null;
    this._data = null;
};

ListFacet.prototype._updateRest = function() {
    Gridworks.update({ engineChanged: true });
};