gerbeur/api/lib/playlist-members.ts

import type { Playlist } from "../model/interfaces.ts";

/** A playlist's dump, with what deciding who may see it takes. */
export interface PlaylistMember {
  id: string;
  isPrivate: boolean;
  userId: string;
}

/**
 * Whether `viewerId` sees this member when the playlist is shown to them: a
 * public dump, or a private one of the owner's own, to the owner. Everyone
 * else — moderators too — doesn't see private dumps, and neither does the
 * owner see someone else's dump once it has gone private.
 */
export function isMemberVisibleTo(
  member: PlaylistMember,
  playlist: Pick<Playlist, "userId">,
  viewerId: string | null | undefined,
): boolean {
  return !member.isPrivate ||
    (member.userId === viewerId && viewerId === playlist.userId);
}