Allow Modal to be used with async-loaded components

Add Modal.createDialogAsync, which can be used to display asynchronously-loaded
React components. Also make EncryptedEventDialog use it as a handy
demonstration.

src/Modal.js

@@ -19,6 +19,53 @@ limitations under the License.
 
 var React = require('react');
 var ReactDOM = require('react-dom');
+import sdk from './index';
+
+/**
+ * Wrap an asynchronous loader function with a react component which shows a
+ * spinner until the real component loads.
+ */
+const AsyncWrapper = React.createClass({
+    propTypes: {
+        /** A function which takes a 'callback' argument which it will call
+         * with the real component once it loads.
+         */
+        loader: React.PropTypes.func.isRequired,
+    },
+
+    getInitialState: function() {
+        return {
+            component: null,
+        }
+    },
+
+    componentWillMount: function() {
+        this._unmounted = false;
+        this.props.loader((e) => {
+            if (this._unmounted) {
+                return;
+            }
+            this.setState({component: e});
+        });
+    },
+
+    componentWillUnmount: function() {
+        this._unmounted = true;
+    },
+
+    render: function() {
+        const {loader, ...otherProps} = this.props;
+
+        if (this.state.component) {
+            const Component = this.state.component;
+            return <Component {...otherProps} />;
+        } else {
+            // show a spinner until the component is loaded.
+            const Spinner = sdk.getComponent("elements.Spinner");
+            return <Spinner />;
+        }
+    },
+});
 
 module.exports = {
     DialogContainerId: "mx_Dialog_Container",
@@ -36,8 +83,30 @@ module.exports = {
     },
 
     createDialog: function (Element, props, className) {
-        var self = this;
+        return this.createDialogAsync((cb) => {cb(Element)}, props, className);
+    },
 
+    /**
+     * Open a modal view.
+     *
+     * This can be used to display a react component which is loaded as an asynchronous
+     * webpack component. To do this, set 'loader' as:
+     *
+     *   (cb) => {
+     *       require(['<module>'], cb);
+     *   }
+     *
+     * @param {Function} loader   a function which takes a 'callback' argument,
+     *   which it should call with a React component which will be displayed as
+     *   the modal view.
+     *
+     * @param {Object} props   properties to pass to the displayed
+     *    component. (We will also pass an 'onFinished' property.)
+     *
+     * @param {String} className   CSS class to apply to the modal wrapper
+     */
+    createDialogAsync: function (loader, props, className) {
+        var self = this;
         // never call this via modal.close() from onFinished() otherwise it will loop
         var closeDialog = function() {
             if (props && props.onFinished) props.onFinished.apply(null, arguments);
@@ -49,7 +118,7 @@ module.exports = {
         var dialog = (
             <div className={"mx_Dialog_wrapper " + className}>
                 <div className="mx_Dialog">
-                    <Element {...props} onFinished={closeDialog}/>
+                     <AsyncWrapper loader={loader} {...props} onFinished={closeDialog}/>
                 </div>
                 <div className="mx_Dialog_background" onClick={ closeDialog.bind(this, false) }></div>
             </div>

src/component-index.js

@@ -75,8 +75,6 @@ import views$dialogs$ChatInviteDialog from './components/views/dialogs/ChatInvit
 views$dialogs$ChatInviteDialog && (module.exports.components['views.dialogs.ChatInviteDialog'] = views$dialogs$ChatInviteDialog);
 import views$dialogs$DeactivateAccountDialog from './components/views/dialogs/DeactivateAccountDialog';
 views$dialogs$DeactivateAccountDialog && (module.exports.components['views.dialogs.DeactivateAccountDialog'] = views$dialogs$DeactivateAccountDialog);
-import views$dialogs$EncryptedEventDialog from './components/views/dialogs/EncryptedEventDialog';
-views$dialogs$EncryptedEventDialog && (module.exports.components['views.dialogs.EncryptedEventDialog'] = views$dialogs$EncryptedEventDialog);
 import views$dialogs$ErrorDialog from './components/views/dialogs/ErrorDialog';
 views$dialogs$ErrorDialog && (module.exports.components['views.dialogs.ErrorDialog'] = views$dialogs$ErrorDialog);
 import views$dialogs$InteractiveAuthDialog from './components/views/dialogs/InteractiveAuthDialog';

src/components/views/rooms/EventTile.js

@@ -366,10 +366,11 @@ module.exports = WithMatrixClient(React.createClass({
     },
 
     onCryptoClicked: function(e) {
-        var EncryptedEventDialog = sdk.getComponent("dialogs.EncryptedEventDialog");
         var event = this.props.mxEvent;
 
-        Modal.createDialog(EncryptedEventDialog, {
+        Modal.createDialogAsync((cb) => {
+            require(['../../../async-components/views/dialogs/EncryptedEventDialog'], cb)
+        }, {
             event: event,
         });
     },