import { useEffect, useRef } from 'react';
import { useAtomValue } from 'jotai';
import { roomToUnreadAtom } from '../state/room/roomToUnread';

// Tauri v2 injects __TAURI_INTERNALS__ into the webview at runtime.
// We use it directly so cinny doesn't need @tauri-apps/api as a dependency.
type TauriInternals = { invoke: (cmd: string, args?: Record<string, unknown>) => Promise<unknown> };
const tauriInvoke = (): TauriInternals['invoke'] | undefined =>
  (window as unknown as { __TAURI_INTERNALS__?: TauriInternals }).__TAURI_INTERNALS__?.invoke;

export function useTauriNotificationBadge() {
  const roomToUnread = useAtomValue(roomToUnreadAtom);
  const prevHighlightsRef = useRef(0);

  useEffect(() => {
    const invoke = tauriInvoke();
    if (!invoke) return;

    let totalHighlights = 0;
    roomToUnread.forEach((unread) => {
      // Sum only leaf rooms (from === null); roomToUnread also holds per-ancestor
      // space aggregates (from = Set), so counting all entries double-counts a
      // space-nested room. Mirrors the favicon fix in ClientNonUIFeatures.
      if (unread.from !== null) return;
      totalHighlights += unread.highlight;
    });

    invoke('set_badge_count', { count: totalHighlights }).catch(() => {});
    // Mirror the unread state onto the tray icon (visible when minimized to tray).
    invoke('set_tray_unread', { unread: totalHighlights > 0 }).catch(() => {});

    // Flash the taskbar button when new mentions arrive and the window is not
    // focused, then reset the baseline.
    if (totalHighlights > prevHighlightsRef.current && !document.hasFocus()) {
      invoke('flash_window').catch(() => {});
    }
    prevHighlightsRef.current = totalHighlights;
  }, [roomToUnread]);
}