element-call/src/lotus/lotusDenoise.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 {
  type LocalAudioTrack,
  ParticipantEvent,
  type Room as LivekitRoom,
  Track,
} from "livekit-client";
import { logger } from "matrix-js-sdk/lib/logger";

import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
import { lotusFlag, lotusParam } from "./lotusWidget";
import {
  type LotusDenoiseConfig,
  LotusDenoiseProcessor,
} from "./lotusDenoiseProcessor";

/**
 * Apply Lotus ML noise suppression to the local mic track as a first-class
 * Element Call audio TrackProcessor (#1), replacing the host's build-time
 * `getUserMedia` monkeypatch.
 *
 * Opt-in via `lotusDenoise=ml` (+ `lotusModel`, `lotusGate`,
 * `lotusGateThreshold`, `lotusDenoiseBase`). Because the processor is attached
 * to the mic publication and re-attached on every (re)publish, denoise
 * survives EC's mid-call reconnect — fixing the A7 "mic dead after reconnect"
 * bug. Additive: no-op without the flag.
 */
export function startLotusDenoise(vm: CallViewModel): () => void {
  if (lotusParam("lotusDenoise") !== "ml") return () => undefined;

  const config: LotusDenoiseConfig = {
    model: lotusParam("lotusModel") === "speex" ? "speex" : "rnnoise",
    assetBase: lotusParam("lotusDenoiseBase") || "./denoise/",
    gate: lotusFlag("lotusGate"),
    gateThreshold: Number(lotusParam("lotusGateThreshold")) || -50,
  };

  const micOf = (room: LivekitRoom): LocalAudioTrack | undefined =>
    room.localParticipant.getTrackPublication(Track.Source.Microphone)
      ?.track as LocalAudioTrack | undefined;

  const apply = (room: LivekitRoom): void => {
    const mic = micOf(room);
    if (mic && !mic.getProcessor()) {
      void mic
        .setProcessor(new LotusDenoiseProcessor(config))
        .catch((e) => logger.warn("[lotus] denoise setProcessor failed", e));
    }
  };

  const roomListeners = new Map<LivekitRoom, () => void>();
  let rooms: LivekitRoom[] = [];

  const sub = vm.livekitRoomItems$.subscribe((items) => {
    const next = items.map((i) => i.livekitRoom);
    rooms = next;
    for (const [room, off] of roomListeners) {
      if (!next.includes(room)) {
        off();
        roomListeners.delete(room);
      }
    }
    for (const room of next) {
      if (!roomListeners.has(room)) {
        // Re-attach on every (re)publish — this is what makes denoise survive
        // reconnects (A7), unlike the old getUserMedia patch.
        const onPublished = (): void => apply(room);
        room.localParticipant.on(
          ParticipantEvent.LocalTrackPublished,
          onPublished,
        );
        roomListeners.set(room, () =>
          room.localParticipant.off(
            ParticipantEvent.LocalTrackPublished,
            onPublished,
          ),
        );
        apply(room);
      }
    }
  });

  return () => {
    sub.unsubscribe();
    for (const off of roomListeners.values()) off();
    roomListeners.clear();
    for (const room of rooms) {
      const mic = micOf(room);
      if (mic?.getProcessor()) void mic.stopProcessor();
    }
  };
}