'use client';

import { useEffect, useRef } from 'react';
import { useAuth } from '@/components/AuthProvider';
import { getSettings, saveDriverLocation, isAuthenticated } from '@/lib/pocketbase';

export default function LocationTracker() {
  const { isLoggedIn } = useAuth();
  const watchRef = useRef<number | null>(null);
  const intervalRef = useRef<ReturnType<typeof setInterval> | null>(null);
  const wakeLockRef = useRef<WakeLockSentinel | null>(null);

  useEffect(() => {
    // Skip entirely when not signed in — previously the watcher
    // was set up regardless of auth, which meant we requested a
    // GPS lock on the login screen (and ate battery doing nothing).
    if (!isLoggedIn) return;
    if (!('geolocation' in navigator)) return;

    const settings = getSettings();
    const intervalMs = Math.max(30000, settings.locationInterval * 1000);

    const sendLocation = (position: GeolocationPosition) => {
      if (!isAuthenticated()) return;
      if (position.coords.accuracy > settings.minimumAccuracy) return;

      const auth = JSON.parse(localStorage.getItem('pocketbase_auth') || '{}');
      const user = auth?.model;
      if (!user) return;

      saveDriverLocation({
        // PB schema note: driver_locations stores the user relation under
        // `relation`, not `driver`. Using the wrong key here silently
        // 400'd inside a try/catch — see lib/types.ts DriverLocation.
        relation: user.id,
        latitude: position.coords.latitude,
        longitude: position.coords.longitude,
        accuracy: position.coords.accuracy || undefined,
        altitude: position.coords.altitude || undefined,
        speed: position.coords.speed || undefined,
        heading: position.coords.heading || undefined,
        timestamp: new Date().toISOString(),
      });
    };

    // 1. watchPosition keeps GPS active (helps Android stay alive longer)
    watchRef.current = navigator.geolocation.watchPosition(
      sendLocation,
      () => {},
      {
        enableHighAccuracy: settings.enableHighAccuracy,
        maximumAge: 5000,        // fresh GPS every 5s
        timeout: 30000,
      }
    );

    // 2. Interval fallback (for when watchPosition is throttled)
    intervalRef.current = setInterval(() => {
      navigator.geolocation.getCurrentPosition(
        sendLocation,
        () => {},
        { enableHighAccuracy: settings.enableHighAccuracy, maximumAge: intervalMs, timeout: 30000 }
      );
    }, intervalMs);

    // 3. Screen Wake Lock — keeps phone awake while app is open
    if ('wakeLock' in navigator) {
      navigator.wakeLock.request('screen')
        .then((lock) => { wakeLockRef.current = lock; })
        .catch(() => {});
      // Re-acquire if page regains focus
      const onFocus = () => {
        if (!wakeLockRef.current) {
          navigator.wakeLock.request('screen')
            .then((lock) => { wakeLockRef.current = lock; })
            .catch(() => {});
        }
      };
      document.addEventListener('visibilitychange', () => {
        if (document.visibilityState === 'visible') onFocus();
      });
    }

    return () => {
      if (watchRef.current !== null) {
        navigator.geolocation.clearWatch(watchRef.current);
        watchRef.current = null;
      }
      if (intervalRef.current !== null) {
        clearInterval(intervalRef.current);
        intervalRef.current = null;
      }
      if (wakeLockRef.current) {
        wakeLockRef.current.release();
        wakeLockRef.current = null;
      }
    };
  }, [isLoggedIn]);

  return null;
}