import { useEffect, useRef } from 'react';
import { refreshManager } from '@/lib/supertokens/refresh-manager';
import { logger } from '@/lib/supertokens';
import { ensureSuperTokensFrontend } from '@/lib/supertokens/client';

export function SessionMonitor() {
  const lastRefreshTimeRef = useRef<number>(0);
  const REFRESH_COOLDOWN = 5 * 1000;

  useEffect(() => {
    if (typeof window === 'undefined') return;

    const handleVisibilityChange = async () => {
      if (document.visibilityState !== 'visible') return;

      const publicRoutes = ['/login', '/logout', '/refresh-session'];
      if (publicRoutes.some(route => window.location.pathname === route)) {
        return;
      }

      const now = Date.now();
      const timeSinceLastRefresh = now - lastRefreshTimeRef.current;

      if (timeSinceLastRefresh < REFRESH_COOLDOWN) {
        logger.info(`Session monitor: skipping refresh (refreshed ${timeSinceLastRefresh}ms ago)`);
        return;
      }

      try {
        ensureSuperTokensFrontend();

        const { doesSessionExist } = await import('supertokens-web-js/recipe/session');

        const sessionExists = await doesSessionExist();
        if (!sessionExists) {
          logger.info('Session monitor: no session exists, skipping refresh');
          return;
        }

        logger.info('Session monitor: tab became visible, checking session freshness');

        const refreshed = await refreshManager.refresh();

        if (refreshed) {
          lastRefreshTimeRef.current = Date.now();
          logger.info('Session monitor: session refreshed successfully');
        } else {
          logger.warn('Session monitor: refresh returned false');
        }
      } catch (error: any) {
        logger.error('Session monitor: error refreshing session', error?.message);
      }
    };

    document.addEventListener('visibilitychange', handleVisibilityChange);

    return () => {
      document.removeEventListener('visibilitychange', handleVisibilityChange);
    };
  }, []);

  return null;
}