import { useEffect, useRef } from 'react';

import { useAuth } from '../context/AuthContext';
import {
  getAutoLockMinutes,
  subscribeAutoLockSetting,
  type AutoLockMinutes,
} from '../lib/autoLockSettings';

const ACTIVITY_EVENTS: Array<keyof WindowEventMap> = [
  'keydown',
  'mousedown',
  'pointermove',
  'touchstart',
  'wheel',
];

// Throttle activity-event resets to once per second to avoid thrashing the
// timer on rapid mouse movement.
const RESET_THROTTLE_MS = 1000;

export function useIdleAutoLock(): void {
  const { session, signOut } = useAuth();
  const minutesRef = useRef<AutoLockMinutes>(getAutoLockMinutes());
  const timerRef = useRef<number | null>(null);
  const lastResetAtRef = useRef<number>(0);

  // Keep minutesRef live to the setting.
  useEffect(() => {
    const unsub = subscribeAutoLockSetting((v) => {
      minutesRef.current = v;
      scheduleNext();
    });
    return unsub;
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  // Helper: schedule the lock based on the current setting.
  function scheduleNext(): void {
    if (timerRef.current !== null) {
      window.clearTimeout(timerRef.current);
      timerRef.current = null;
    }
    const min = minutesRef.current;
    if (min === 0) return; // disabled
    timerRef.current = window.setTimeout(() => {
      timerRef.current = null;
      // Fire the lock. signOut wipes local state and navigates to /device
      // (PIN re-entry screen).
      void signOut().catch((err) => console.warn('auto-lock signOut failed', err));
    }, min * 60 * 1000);
  }

  useEffect(() => {
    if (!session) return;
    scheduleNext();

    const onActivity = () => {
      const now = Date.now();
      if (now - lastResetAtRef.current < RESET_THROTTLE_MS) return;
      lastResetAtRef.current = now;
      scheduleNext();
    };

    for (const ev of ACTIVITY_EVENTS) {
      window.addEventListener(ev, onActivity, { passive: true });
    }
    return () => {
      for (const ev of ACTIVITY_EVENTS) {
        window.removeEventListener(ev, onActivity);
      }
      if (timerRef.current !== null) {
        window.clearTimeout(timerRef.current);
        timerRef.current = null;
      }
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [session]);
}