"use client";

/**
 * Which conversation the chat screen is currently showing, for surfaces
 * outside the chat route (the sidebar list highlights it). A tiny external
 * store instead of reading `?c=` from the URL, because the sidebar renders on
 * every page and `useSearchParams` there would force pages dynamic.
 */

let active: string | null = null;
const listeners = new Set<() => void>();

export const chatActive = {
  set(id: string | null): void {
    if (active === id) return;
    active = id;
    listeners.forEach((listener) => listener());
  },
  subscribe(listener: () => void): () => void {
    listeners.add(listener);
    return () => listeners.delete(listener);
  },
  getSnapshot(): string | null {
    return active;
  },
  getServerSnapshot(): string | null {
    return null;
  },
};