Add managed hybrid call widgets when supported

If your homeserver is configured with an experiment `widget_build_url`, this
will take over the functionality of the call buttons and turn them into a
general widget installer.

src/widgets/ManagedHybrid.ts

@@ -0,0 +1,102 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { IWidget } from "matrix-widget-api";
+import { MatrixClientPeg } from "../MatrixClientPeg";
+import { getCallBehaviourWellKnown } from "../utils/WellKnownUtils";
+import WidgetUtils from "../utils/WidgetUtils";
+import { IStoredLayout, WidgetLayoutStore } from "../stores/widgets/WidgetLayoutStore";
+import WidgetEchoStore from "../stores/WidgetEchoStore";
+import WidgetStore from "../stores/WidgetStore";
+
+/* eslint-disable camelcase */
+interface IManagedHybridWidgetData {
+    widget_id: string;
+    widget: IWidget;
+    layout: IStoredLayout;
+}
+/* eslint-enable camelcase */
+
+export function isManagedHybridWidgetEnabled(): boolean {
+    const callBehaviour = getCallBehaviourWellKnown();
+    /* eslint-disable-next-line camelcase */
+    return !!callBehaviour?.widget_build_url;
+}
+
+export async function addManagedHybridWidget(roomId: string) {
+    const cli = MatrixClientPeg.get();
+    const room = cli.getRoom(roomId);
+    if (!room) {
+        return;
+    }
+
+    // Check for permission
+    if (!WidgetUtils.canUserModifyWidgets(roomId)) {
+        console.error(`User not allowed to modify widgets in ${roomId}`);
+        return;
+    }
+
+    // Get widget data
+    /* eslint-disable-next-line camelcase */
+    const widgetBuildUrl = getCallBehaviourWellKnown()?.widget_build_url;
+    if (!widgetBuildUrl) {
+        return;
+    }
+    let widgetData: IManagedHybridWidgetData;
+    try {
+        const response = await fetch(`${widgetBuildUrl}?roomId=${roomId}`);
+        widgetData = await response.json();
+    } catch (e) {
+        console.error(`Managed hybrid widget builder failed for room ${roomId}`, e);
+        return;
+    }
+    if (!widgetData) {
+        return;
+    }
+    const { widget_id: widgetId, widget: widgetContent, layout } = widgetData;
+
+    // Ensure the widget is not already present in the room
+    let widgets = WidgetStore.instance.getApps(roomId);
+    const existing = (
+        widgets.some(w => w.id === widgetId) ||
+        WidgetEchoStore.roomHasPendingWidgets(roomId, [])
+    );
+    if (existing) {
+        console.error(`Managed hybrid widget already present in room ${roomId}`);
+        return;
+    }
+
+    // Add the widget
+    try {
+        await WidgetUtils.setRoomWidgetContent(roomId, widgetId, widgetContent);
+    } catch (e) {
+        console.error(`Unable to add managed hybrid widget in room ${roomId}`, e);
+        return;
+    }
+
+    // Move the widget into position
+    if (!WidgetLayoutStore.instance.canCopyLayoutToRoom(room)) {
+        return;
+    }
+    widgets = WidgetStore.instance.getApps(roomId);
+    const installedWidget = widgets.find(w => w.id === widgetId);
+    if (!installedWidget) {
+        return;
+    }
+    WidgetLayoutStore.instance.moveToContainer(room, installedWidget, layout.container);
+    WidgetLayoutStore.instance.setContainerHeight(room, layout.container, layout.height);
+    WidgetLayoutStore.instance.copyLayoutToRoom(room);
+}