/**
 * [Gitea #342] Whether a voice channel with an `io.lotus.voice_limit` is full.
 * Counts distinct PEOPLE, not call memberships: a MatrixRTC membership is per
 * device, so one user on desktop + phone (or with a crashed tab's membership
 * not yet expired) used to fill two slots. This matches the server-side guard
 * (matrix `voice-limit-guard.py`, which reduces LiveKit identities to users).
 */
export type VoiceChannelOccupancy = {
  channelFull: boolean;
  /** Distinct users in the call. */
  current: number;
  max: number;
};

export const voiceChannelOccupancy = (
  memberSenders: Array<string | undefined>,
  myUserId: string,
  maxUsers: number,
): VoiceChannelOccupancy => {
  const users = new Set(memberSenders.filter((s): s is string => !!s));
  // A user already in the call (another device, or rejoining) is never blocked.
  const alreadyMember = users.has(myUserId);
  const channelFull = maxUsers > 0 && !alreadyMember && users.size >= maxUsers;
  return { channelFull, current: users.size, max: maxUsers };
};