"use client";

/**
 * True while either wizard is generating. The in-page mode switch reads this
 * and hides itself, so a loading run can't be swapped out mid-flight — the
 * loading screen owns the page until it finishes or is cancelled.
 */

import { useSyncExternalStore } from "react";

let busy = false;
const listeners = new Set<() => void>();

export const wizardBusy = {
  subscribe(listener: () => void): () => void {
    listeners.add(listener);
    return () => listeners.delete(listener);
  },
  getSnapshot(): boolean {
    return busy;
  },
  getServerSnapshot(): boolean {
    return false;
  },
  set(value: boolean): void {
    if (busy === value) return;
    busy = value;
    listeners.forEach((listener) => listener());
  },
};

export function useWizardBusy(): boolean {
  return useSyncExternalStore(wizardBusy.subscribe, wizardBusy.getSnapshot, wizardBusy.getServerSnapshot);
}