[Edit] Add toolbar representer

Add a representer to handle exposing toolbars for views in
edit mode. WTD-878.

platform/commonUI/edit/src/representers/EditToolbarRepresenter.js

@@ -1,8 +1,95 @@
 /*global define*/
 
 define(
-    [],
-    function () {
+    ['./EditToolbar'],
+    function (EditToolbar) {
         "use strict";
+
+        // No operation
+        function noop() {}
+
+        /**
+         * The EditToolbarRepresenter populates the toolbar in Edit mode
+         * based on a view's definition.
+         * @param {Scope} scope the Angular scope of the representation
+         * @constructor
+         */
+        function EditToolbarRepresenter(scope, element, attrs) {
+            var definition,
+                unwatch,
+                toolbar,
+                toolbarObject = {};
+
+            // Handle changes to the current selection
+            function updateSelection(selection) {
+                // Make sure selection is array-like
+                selection = Array.isArray(selection) ?
+                        selection :
+                        (selection ? [selection] : []);
+
+                // Instantiate a new toolbar...
+                toolbar = new EditToolbar(definition, selection);
+
+                // ...and expose its structure/state
+                toolbarObject.structure = toolbar.getStructure();
+                toolbarObject.state = toolbar.getState();
+            }
+
+            // Update selection models to match changed toolbar state
+            function updateState(state) {
+                state.forEach(toolbar.updateState);
+            }
+
+            // Represent a domain object using this definition
+            function represent(representation) {
+                // Clear any existing selection
+                scope.selection = [];
+                // Get the newest toolbar definition from the view
+                definition = (representation || {}).toolbar || {};
+                // Initialize toolbar to an empty selection
+                updateSelection([]);
+            }
+
+            // Destroy; stop watching the parent for changes in
+            // toolbar state.
+            function destroy() {
+                if (unwatch) {
+                    unwatch();
+                    unwatch = undefined;
+                }
+            }
+
+            // If we have been asked to expose toolbar state...
+            if (attrs.toolbar) {
+                // Expose toolbar state under that name
+                scope.$parent[attrs.toolbar] = toolbarObject;
+                // Detect and handle changes to state from the toolbar
+                unwatch = scope.$parent.$watchCollection(
+                    attrs.toolbar + ".state",
+                    updateState
+                );
+                // Watch for changes in the current selection state
+                scope.$watchCollection("selection", updateSelection);
+            }
+
+            return {
+                /**
+                 * Set the current representation in use, and the domain
+                 * object being represented.
+                 *
+                 * @param {RepresentationDefinition} representation the
+                 *        definition of the representation in use
+                 * @param {DomainObject} domainObject the domain object
+                 *        being represented
+                 */
+                represent: (attrs || {}).toolbar ? represent : noop,
+                /**
+                 * Release any resources associated with this representer.
+                 */
+                destroy: (attrs || {}).toolbar ? destroy : noop
+            };
+        }
+
+        return EditToolbarRepresenter;
     }
 );