refactor: Extract layout mode switch + test

src/state/CallViewModel/CallViewModel.ts

@@ -15,7 +15,6 @@ import {
 } from "livekit-client";
 import { type Room as MatrixRoom } from "matrix-js-sdk";
 import {
-  BehaviorSubject,
   combineLatest,
   distinctUntilChanged,
   filter,
@@ -126,6 +125,7 @@ import {
 } from "./remoteMembers/MatrixMemberMetadata.ts";
 import { Publisher } from "./localMember/Publisher.ts";
 import { type Connection } from "./remoteMembers/Connection.ts";
+import { createLayoutModeSwitch } from "./LayoutSwitch.ts";
 
 const logger = rootLogger.getChild("[CallViewModel]");
 //TODO
@@ -343,6 +343,7 @@ export interface CallViewModel {
   // DISCUSSION own membership manager ALSO this probably can be simplifis
   reconnecting$: Behavior<boolean>;
 }
+
 /**
  * A view model providing all the application logic needed to show the in-call
  * UI (may eventually be expanded to cover the lobby and feedback screens in the
@@ -980,49 +981,11 @@ export function createCallViewModel$(
     spotlightExpandedToggle$.pipe(accumulate(false, (expanded) => !expanded)),
   );
 
-  const gridModeUserSelection$ = new BehaviorSubject<GridMode>("grid");
-
-  // Callback to set the grid mode desired by the user.
-  // Notice that this is only a preference, the actual grid mode can be overridden
-  // if there is a remote screen share active.
-  const setGridMode = (value: GridMode): void => {
-    gridModeUserSelection$.next(value);
-  };
-  /**
-   * The layout mode of the media tile grid.
-   */
-  const gridMode$ =
-    // If the user hasn't selected spotlight and somebody starts screen sharing,
-    // automatically switch to spotlight mode and reset when screen sharing ends
-    scope.behavior<GridMode>(
-      gridModeUserSelection$.pipe(
-        switchMap((userSelection): Observable<GridMode> => {
-          if (userSelection === "spotlight") {
-            // If already in spotlight mode, stay there
-            return of("spotlight");
-          } else {
-            // Otherwise, check if there is a remote screen share active
-            // as this could force us into spotlight mode.
-            return combineLatest([hasRemoteScreenShares$, windowMode$]).pipe(
-              map(([hasScreenShares, windowMode]): GridMode => {
-                const isFlatMode = windowMode === "flat";
-                if (hasScreenShares || isFlatMode) {
-                  logger.debug(
-                    `Forcing spotlight mode, hasScreenShares=${hasScreenShares} windowMode=${windowMode}`,
-                  );
-                  // override to spotlight mode
-                  return "spotlight";
-                } else {
-                  // respect user choice
-                  return "grid";
-                }
-              }),
-            );
-          }
-        }),
-      ),
-      "grid",
-    );
+  const { setGridMode, gridMode$ } = createLayoutModeSwitch(
+    scope,
+    windowMode$,
+    hasRemoteScreenShares$,
+  );
 
   const gridLayoutMedia$: Observable<GridLayoutMedia> = combineLatest(
     [grid$, spotlight$],

src/state/CallViewModel/Layout.switch.test.ts

@@ -0,0 +1,134 @@
+/*
+Copyright 2025 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { afterEach, beforeEach, describe, expect, test } from "vitest";
+import { firstValueFrom, of } from "rxjs";
+
+import { createLayoutModeSwitch } from "./LayoutSwitch";
+import { ObservableScope } from "../ObservableScope";
+import { constant } from "../Behavior";
+import { withTestScheduler } from "../../utils/test";
+
+let scope: ObservableScope;
+beforeEach(() => {
+  scope = new ObservableScope();
+});
+afterEach(() => {
+  scope.end();
+});
+
+describe("Default mode", () => {
+  test("Should be in grid layout by default", async () => {
+    const { gridMode$ } = createLayoutModeSwitch(
+      scope,
+      constant("normal"),
+      of(false),
+    );
+
+    const mode = await firstValueFrom(gridMode$);
+    expect(mode).toBe("grid");
+  });
+
+  test("Should switch to spotlight mode when window mode is flat", async () => {
+    const { gridMode$ } = createLayoutModeSwitch(
+      scope,
+      constant("flat"),
+      of(false),
+    );
+
+    const mode = await firstValueFrom(gridMode$);
+    expect(mode).toBe("spotlight");
+  });
+});
+
+test("Should allow switching modes manually", () => {
+  withTestScheduler(({ cold, behavior, expectObservable, schedule }): void => {
+    const { gridMode$, setGridMode } = createLayoutModeSwitch(
+      scope,
+      behavior("n", { n: "normal" }),
+      cold("f", { f: false, t: true }),
+    );
+
+    schedule("--sgs", {
+      s: () => setGridMode("spotlight"),
+      g: () => setGridMode("grid"),
+    });
+
+    expectObservable(gridMode$).toBe("g-sgs", {
+      g: "grid",
+      s: "spotlight",
+    });
+  });
+});
+
+test("Should switch to spotlight mode when there is a remote screen share", () => {
+  withTestScheduler(({ cold, behavior, expectObservable }): void => {
+    const shareMarble = "f--t";
+    const gridsMarble = "g--s";
+    const { gridMode$ } = createLayoutModeSwitch(
+      scope,
+      behavior("n", { n: "normal" }),
+      cold(shareMarble, { f: false, t: true }),
+    );
+
+    expectObservable(gridMode$).toBe(gridsMarble, {
+      g: "grid",
+      s: "spotlight",
+    });
+  });
+});
+
+test.fails("Can manually force grid when there is a screenshare", () => {
+  withTestScheduler(({ cold, behavior, expectObservable, schedule }): void => {
+    const { gridMode$, setGridMode } = createLayoutModeSwitch(
+      scope,
+      behavior("n", { n: "normal" }),
+      cold("-ft", { f: false, t: true }),
+    );
+
+    schedule("---g", {
+      g: () => setGridMode("grid"),
+    });
+
+    expectObservable(gridMode$).toBe("ggsg", {
+      g: "grid",
+      s: "spotlight",
+    });
+  });
+});
+
+test("Should switch back to grid mode when the remote screen share ends", () => {
+  withTestScheduler(({ cold, behavior, expectObservable }): void => {
+    const shareMarble = "f--t--f-";
+    const gridsMarble = "g--s--g-";
+    const { gridMode$ } = createLayoutModeSwitch(
+      scope,
+      behavior("n", { n: "normal" }),
+      cold(shareMarble, { f: false, t: true }),
+    );
+
+    expectObservable(gridMode$).toBe(gridsMarble, {
+      g: "grid",
+      s: "spotlight",
+    });
+  });
+});
+
+test("Should auto-switch to spotlight when in flat window mode", () => {
+  withTestScheduler(({ cold, behavior, expectObservable }): void => {
+    const { gridMode$ } = createLayoutModeSwitch(
+      scope,
+      behavior("naf", { n: "normal", a: "narrow", f: "flat" }),
+      cold("f", { f: false, t: true }),
+    );
+
+    expectObservable(gridMode$).toBe("g-s-", {
+      g: "grid",
+      s: "spotlight",
+    });
+  });
+});

src/state/CallViewModel/LayoutSwitch.ts

@@ -0,0 +1,89 @@
+/*
+Copyright 2025 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import {
+  BehaviorSubject,
+  combineLatest,
+  map,
+  switchMap,
+  type Observable,
+  of,
+} from "rxjs";
+import { logger } from "matrix-js-sdk/lib/logger";
+
+import { type GridMode, type WindowMode } from "./CallViewModel.ts";
+import { type Behavior } from "../Behavior.ts";
+import { type ObservableScope } from "../ObservableScope.ts";
+
+/**
+ * Creates a layout mode switch that allows switching between grid and spotlight modes.
+ * The actual layout mode can be overridden to spotlight mode if there is a remote screen share active
+ * or if the window mode is flat.
+ *
+ * @param scope - The observable scope to manage subscriptions.
+ * @param windowMode$ - The current window mode observable.
+ * @param hasRemoteScreenShares$ - An observable indicating if there are remote screen shares active.
+ */
+export function createLayoutModeSwitch(
+  scope: ObservableScope,
+  windowMode$: Behavior<WindowMode>,
+  hasRemoteScreenShares$: Observable<boolean>,
+): {
+  gridMode$: Behavior<GridMode>;
+  setGridMode: (value: GridMode) => void;
+} {
+  const gridModeUserSelection$ = new BehaviorSubject<GridMode>("grid");
+
+  // Callback to set the grid mode desired by the user.
+  // Notice that this is only a preference, the actual grid mode can be overridden
+  // if there is a remote screen share active.
+  const setGridMode = (value: GridMode): void => {
+    gridModeUserSelection$.next(value);
+  };
+  /**
+   * The layout mode of the media tile grid.
+   */
+  const gridMode$ =
+    // If the user hasn't selected spotlight and somebody starts screen sharing,
+    // automatically switch to spotlight mode and reset when screen sharing ends
+    scope.behavior<GridMode>(
+      gridModeUserSelection$.pipe(
+        switchMap((userSelection): Observable<GridMode> => {
+          if (userSelection === "spotlight") {
+            // If already in spotlight mode, stay there
+            return of("spotlight");
+          } else {
+            // Otherwise, check if there is a remote screen share active
+            // as this could force us into spotlight mode.
+            return combineLatest([hasRemoteScreenShares$, windowMode$]).pipe(
+              map(([hasScreenShares, windowMode]): GridMode => {
+                // TODO: strange that we do that for flat mode but not for other modes?
+                // TODO: Why is this not handled in layoutMedia$ like other window modes?
+                const isFlatMode = windowMode === "flat";
+                if (hasScreenShares || isFlatMode) {
+                  logger.debug(
+                    `Forcing spotlight mode, hasScreenShares=${hasScreenShares} windowMode=${windowMode}`,
+                  );
+                  // override to spotlight mode
+                  return "spotlight";
+                } else {
+                  // respect user choice
+                  return "grid";
+                }
+              }),
+            );
+          }
+        }),
+      ),
+      "grid",
+    );
+
+  return {
+    gridMode$,
+    setGridMode,
+  };
+}