element-call/src/lotus/lotusScreenshareAudio.ts

/*
Copyright 2026 Lotus Guild

SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE in the repository root for full details.
*/

import { BehaviorSubject } from "rxjs";

import { globalScope } from "../state/ObservableScope";
import { LotusWidgetActions } from "./lotusActions";
import { lotusSendToHost } from "./lotusWidget";

/**
 * Whether the host has muted remote screenshare AUDIO (`io.lotus.set_deafen`
 * `screenshareAudioMuted`). Consumed by `LivekitRoomAudioRenderer` exactly the
 * way `muteAllAudio$` is: it becomes the `muted` prop of every
 * `Track.Source.ScreenShareAudio` element, so it survives re-renders, applies
 * to tracks that are published LATER (a sharer stopping and re-sharing, a late
 * joiner) and never fights EC's per-tile volume controls — which was the
 * failure mode of the old `RemoteParticipant.setVolume(0, ScreenShareAudio)`
 * approach: `createVolumeControls` writes its own volume (1) through the same
 * sink the moment a new screenshare media item appears, un-muting it.
 */
export const setScreenshareAudioMuted$ = new BehaviorSubject(false);

export const muteScreenshareAudio$ = globalScope.behavior(
  setScreenshareAudioMuted$,
);

/**
 * [cinny #277] Whether any remote participant's screenshare AUDIO is being
 * received, so the host shows its "Mute Screenshare Audio" control only when
 * there is something to mute. Each `LivekitRoomAudioRenderer` (one per SFU)
 * reports for its own room; the host gets `io.lotus.screenshare_audio_state
 * { present }` whenever the combined answer changes.
 */
const presentByRoom = new Map<string, boolean>();
let lastSent: boolean | undefined;

function sendIfChanged(): void {
  const present = [...presentByRoom.values()].some(Boolean);
  if (present === lastSent) return;
  lastSent = present;
  lotusSendToHost(LotusWidgetActions.ScreenshareAudioState, { present });
}

export function reportScreenshareAudio(
  roomKey: string,
  present: boolean,
): void {
  presentByRoom.set(roomKey, present);
  sendIfChanged();
}

/** The renderer for `roomKey` went away (call left, SFU switched). */
export function clearScreenshareAudio(roomKey: string): void {
  presentByRoom.delete(roomKey);
  sendIfChanged();
}

/** Test-only: forget all reports. */
export function resetScreenshareAudioPresence(): void {
  presentByRoom.clear();
  lastSent = undefined;
}