function ExtendDataPreviewDialog(column, columnIndex, rowIndices, onDone) {
    this._column = column;
    this._columnIndex = columnIndex;
    this._rowIndices = rowIndices;
    this._onDone = onDone;
    this._extension = { properties: [] };

    var self = this;
    var frame = this._frame = DialogSystem.createDialog();
    frame.width("1000px").addClass("extend-data-preview-dialog");
    
    var header = $('<div></div>').addClass("dialog-header").text("Add Columns from Freebase Based on Column " + column.name).appendTo(frame);
    var body = $('<div></div>').addClass("dialog-body").appendTo(frame);
    var footer = $('<div></div>').addClass("dialog-footer").appendTo(frame);
    var html = $(
        '<div class="grid-layout layout-normal layout-full"><table rows="4">' +
            '<tr>' +
                '<td width="300" height="1">Add Property</td>' +
                '<td height="1">Preview</td>' +
                '<td height="1" width="1%"><button bind="resetButton">Reset</button></td>' +
            '</tr>' +
            '<tr>' +
                '<td style="vertical-align: top;" height="1"><div class="input-container"><input bind="addPropertyInput" /></div></td>' +
                '<td style="vertical-align: top;" rowspan="3" colspan="2"><div class="preview-container" bind="previewContainer"></div></td>' +
            '</tr>' +
            '<tr>' +
                '<td height="1">Suggested Properties</td>' +
            '</tr>' +
            '<tr>' +
                '<td><div class="suggested-property-container" bind="suggestedPropertyContainer"></div></td>' +
            '</tr>' +
        '</table></div>'
    ).appendTo(body);
    
    this._elmts = DOM.bind(html);
    
    this._elmts.resetButton.click(function() {
        self._extension.properties = [];
        self._update();
    });
    
    $('<button></button>').html("&nbsp;&nbsp;OK&nbsp;&nbsp;").click(function() {
        if (self._extension.properties.length === 0) {
            alert("Please add some properties first.");
        } else {
            DialogSystem.dismissUntil(self._level - 1);
            self._onDone(self._extension);
        }
    }).appendTo(footer);
    
    $('<button></button>').text("Cancel").click(function() {
        DialogSystem.dismissUntil(self._level - 1);
    }).appendTo(footer);
    
    var dismissBusy = DialogSystem.showBusy();
    var type = "reconConfig" in column && "type" in column.reconConfig ? column.reconConfig.type.id : "/common/topic";
    
    ExtendDataPreviewDialog.getAllProperties(type, function(properties) {
        dismissBusy();
        self._show(properties);
    });
}

ExtendDataPreviewDialog.getAllProperties = function(typeID, onDone) {
    var done = false;
    
    $.getJSON(
        Gridworks.gridworksHelperService + "get_properties_of_type?type=" + typeID + "&callback=?",
        null,
        function(data) {
            if (done) return;
            done = true;
            
            var allProperties = [];
            for (var i = 0; i < data.properties.length; i++) {
                var property = data.properties[i];
                var property2 = {
                    id: property.id,
                    name: property.name
                };
                if ("id2" in property) {
                    property2.expected = property.schema2;
                    property2.properties = [{
                        id: property.id2,
                        name: property.name2,
                        expected: property.expects
                    }];
                } else {
                    property2.expected = property.expects;
                }
                allProperties.push(property2);
            }
            allProperties.sort(function(a, b) { return a.name.localeCompare(b.name); });
            
            onDone(allProperties);
        }
    );
    
    window.setTimeout(function() {
        if (done) return;
        
        done = true;
        onDone([]);
    }, 7000); // time to give up?
};

ExtendDataPreviewDialog.prototype._show = function(properties) {
    this._level = DialogSystem.showDialog(this._frame);
    
    var n = this._elmts.suggestedPropertyContainer.offset().top +
        this._elmts.suggestedPropertyContainer.outerHeight(true) -
        this._elmts.addPropertyInput.offset().top;
        
    this._elmts.previewContainer.height(Math.floor(n));
    
    var self = this;
    var container = this._elmts.suggestedPropertyContainer;
    var renderSuggestedProperty = function(property) {
        var label = ("properties" in property) ? (property.name + " &raquo; " + property.properties[0].name) : property.name;
        var div = $('<div>').addClass("suggested-property").appendTo(container);
        
        $('<a>')
            .attr("href", "javascript:{}")
            .html(label)
            .appendTo(div)
            .click(function() {
                self._addProperty(property);
            });
    };
    for (var i = 0; i < properties.length; i++) {
        renderSuggestedProperty(properties[i]);
    }
    
    var suggestConfig = {
        type: '/type/property'
    };
    if ("reconConfig" in this._column && "type" in this._column.reconConfig) {
        suggestConfig.schema = this._column.reconConfig.type.id;
    }
    
    this._elmts.addPropertyInput.suggestP(suggestConfig).bind("fb-select", function(evt, data) {
        var expected = data.expected_type;
        self._addProperty({
            id : data.id,
            name: data.name,
            expected: {
                id: expected.id,
                name: expected.name
            }
        });
    });
};

ExtendDataPreviewDialog.prototype._update = function() {
    this._elmts.previewContainer.empty().text("Querying Freebase ...");
    
    var self = this;
    var params = {
        project: theProject.id,
        columnName: this._column.name
    };
    
    $.post(
        "/command/preview-extend-data?" + $.param(params), 
        {
            rowIndices: JSON.stringify(this._rowIndices),
            extension: JSON.stringify(this._extension)
        },
        function(data) {
            self._renderPreview(data);
        },
        "json"
    );
};

ExtendDataPreviewDialog.prototype._addProperty = function(p) {
    var addSeveralToList = function(properties, oldProperties) {
        for (var i = 0; i < properties.length; i++) {
            addToList(properties[i], oldProperties);
        }
    };
    var addToList = function(property, oldProperties) {
        for (var i = 0; i < oldProperties.length; i++) {
            var oldProperty = oldProperties[i];
            if (oldProperty.id == property.id) {
                if ("included" in property) {
                    oldProperty.included = "included" in oldProperty ? 
                        (oldProperty.included || property.included) : 
                        property.included;
                }
                
                if ("properties" in property) {
                    if ("properties" in oldProperty) {
                        addSeveralToList(property.properties, oldProperty.properties);
                    } else {
                        oldProperty.properties = property.properties;
                    }
                }
                return;
            }
        }
        
        oldProperties.push(property);
    };
    
    addToList(p, this._extension.properties);
    
    this._update();
};

ExtendDataPreviewDialog.prototype._renderPreview = function(data) {
    var self = this;
    var container = this._elmts.previewContainer.empty();
    if (data.code == "error") {
        container.text("Error.");
        return;
    }
    
    var table = $('<table>')[0];
    var trHead = table.insertRow(table.rows.length);
    $('<th>').appendTo(trHead).text(this._column.name);
    
    var renderColumnHeader = function(column) {
        var th = $('<th>').appendTo(trHead);
        
        $('<span>').html(column.names.join(" &raquo; ")).appendTo(th);
        $('<br>').appendTo(th);
        
        $('<a href="javascript:{}"></a>')
            .text("remove")
            .addClass("action")
            .attr("title", "Remove this column")
            .click(function() {
                self._removeProperty(column.path);
            }).appendTo(th);
            
        $('<a href="javascript:{}"></a>')
            .text("constrain")
            .addClass("action")
            .attr("title", "Add constraints to this column")
            .click(function() {
                self._constrainProperty(column.path);
            }).appendTo(th);
    };
    for (var c = 0; c < data.columns.length; c++) {
        renderColumnHeader(data.columns[c]);
    }
    
    for (var r = 0; r < data.rows.length; r++) {
        var tr = table.insertRow(table.rows.length);
        var row = data.rows[r];
        
        for (var c = 0; c < row.length; c++) {
            var td = tr.insertCell(tr.cells.length);
            var cell = row[c];
            if (cell !== null) {
                if ($.isPlainObject(cell)) {
                    $('<a>').attr("href", "http://www.freebase.com/view" + cell.id).text(cell.name).appendTo(td);
                } else {
                    $('<span>').text(cell).appendTo(td);
                }
            }
        }
    }
    
    container.append(table);
};

ExtendDataPreviewDialog.prototype._removeProperty = function(path) {
    var removeFromList = function(path, index, properties) {
        var id = path[index];
        
        for (var i = properties.length - 1; i >= 0; i--) {
            var property = properties[i];
            if (property.id == id) {
                if (index === path.length - 1) {
                    if ("included" in property) {
                        delete property.included;
                    }
                } else if ("properties" in property && property.properties.length > 0) {
                    removeFromList(path, index + 1, property.properties);
                }
                
                if (!("properties" in property) || property.properties.length === 0) {
                    properties.splice(i, 1);
                }
                
                return;
            }
        }
    };
    
    removeFromList(path, 0, this._extension.properties);
    
    this._update();
};

ExtendDataPreviewDialog.prototype._findProperty = function(path) {
    var find = function(path, index, properties) {
        var id = path[index];
        
        for (var i = properties.length - 1; i >= 0; i--) {
            var property = properties[i];
            if (property.id == id) {
                if (index === path.length - 1) {
                    return property;
                } else if ("properties" in property && property.properties.length > 0) {
                    return find(path, index + 1, property.properties);
                }
                break;
            }
        }
        
        return null;
    };
    
    return find(path, 0, this._extension.properties);
};

ExtendDataPreviewDialog.prototype._constrainProperty = function(path) {
    var self = this;
    var property = this._findProperty(path);
    
    var frame = DialogSystem.createDialog();
    frame.width("500px");
    
    var header = $('<div></div>').addClass("dialog-header").text("Constrain " + path.join(" > ")).appendTo(frame);
    var body = $('<div></div>').addClass("dialog-body").appendTo(frame);
    var footer = $('<div></div>').addClass("dialog-footer").appendTo(frame);
    
    body.html(
        '<div class="grid-layout layout-normal layout-full"><table>' +
            '<tr><td>' +
                'Enter MQL query constraints as JSON' +
            '</td></tr>' +
            '<tr><td>' +
                '<textarea style="width: 100%; height: 300px; font-family: monospace;" bind="textarea"></textarea>' +
            '</td></tr>' +
        '</table></div>'
    );
    var bodyElmts = DOM.bind(body);
    
    if ("constraints" in property) {
        bodyElmts.textarea[0].value = JSON.stringify(property.constraints, null, 2);
    } else {
        bodyElmts.textarea[0].value = JSON.stringify({ "limit" : 10 }, null, 2);
    }
    
    footer.html(
        '<button bind="okButton">&nbsp;&nbsp;OK&nbsp;&nbsp;</button>' +
        '<button bind="cancelButton">Cancel</button>'
    );
    var footerElmts = DOM.bind(footer);
    
    var level = DialogSystem.showDialog(frame);
    var dismiss = function() {
        DialogSystem.dismissUntil(level - 1);
    };
    
    footerElmts.cancelButton.click(dismiss);
    footerElmts.okButton.click(function() {
        try {
            var o = JSON.parse(bodyElmts.textarea[0].value);
            if (o === undefined) {
                alert("Please ensure that the JSON you enter is valid.");
                return;
            }
            
            if ($.isArray(o) && o.length == 1) {
                o = o[0];
            }
            if (!$.isPlainObject(o)) {
                alert("The JSON you enter must be an object, that is, it is of this form { ... }.");
                return;
            }
            
            property.constraints = o;
            
            dismiss();
            
            self._update();
        } catch (e) {
            //console.log(e);
        }
    });
    
    bodyElmts.textarea.focus();
};