cinny/src/app/hooks/useTauriFocusAssist.ts

import { useEffect } from 'react';
import { useSetAtom } from 'jotai';
import { focusAssistActiveAtom } from '../state/focusAssist';
import { tauriInvoke, useTauriEvent } from './useTauri';

/** Detail shape of the `focus-assist-changed` event emitted by the native side. */
type FocusAssistChangedDetail = {
  active: boolean;
};

/**
 * P5-56 — Windows Focus Assist ↔ Do-Not-Disturb sync (desktop). Subscribes to
 * the native `focus-assist-changed` event (Windows `SHQueryUserNotificationState`
 * poll, `{ active }`) and mirrors it into `focusAssistActiveAtom`, which the
 * notification gate reads to suppress notifications while the shell is in Focus
 * Assist / Quiet Hours, presenting, gaming full-screen, or busy. Inert in the
 * browser, since `useTauriEvent` only listens under Tauri.
 */
export function useTauriFocusAssist(): void {
  const setFocusAssist = useSetAtom(focusAssistActiveAtom);

  useTauriEvent<FocusAssistChangedDetail>('focus-assist-changed', ({ active }) =>
    setFocusAssist(active),
  );

  // Hydrate on mount. The native poll only emits on a transition, and its first
  // reading lands during app setup before this page is listening — so with Focus
  // Assist already on at launch (or after a reload) notifications leaked until
  // the OS state next flipped (cinny-desktop #15). `null` = no reading yet.
  useEffect(() => {
    tauriInvoke()?.('get_focus_assist')
      .then((active) => {
        if (typeof active === 'boolean') setFocusAssist(active);
      })
      .catch(() => undefined);
  }, [setFocusAssist]);
}