import { useCallback, useEffect, useState } from 'react';
import * as Location from 'expo-location';
import AsyncStorage from '@react-native-async-storage/async-storage';

export interface Coords {
  latitude: number;
  longitude: number;
}

const LAST_LOC_KEY = 'ps_last_location';

/** Persist the most recent fix so the "near my last location" button works cold. */
async function saveLastLocation(c: Coords) {
  await AsyncStorage.setItem(LAST_LOC_KEY, JSON.stringify(c));
}
export async function getLastKnownSavedLocation(): Promise<Coords | null> {
  const raw = await AsyncStorage.getItem(LAST_LOC_KEY);
  return raw ? (JSON.parse(raw) as Coords) : null;
}

/**
 * Foreground location. On GrapheneOS this uses the OS location provider directly
 * (no Google Play Services). We prefer a fast last-known fix, then refine.
 */
export function useLocation() {
  const [coords, setCoords] = useState<Coords | null>(null);
  const [granted, setGranted] = useState<boolean | null>(null);
  const [error, setError] = useState<string | null>(null);

  const refresh = useCallback(async () => {
    try {
      const { status } = await Location.requestForegroundPermissionsAsync();
      const ok = status === 'granted';
      setGranted(ok);
      if (!ok) {
        setError('Location permission denied.');
        return null;
      }
      const last = await Location.getLastKnownPositionAsync();
      if (last) {
        const c = { latitude: last.coords.latitude, longitude: last.coords.longitude };
        setCoords(c);
        void saveLastLocation(c);
      }
      const cur = await Location.getCurrentPositionAsync({
        accuracy: Location.Accuracy.Balanced,
      });
      const c = { latitude: cur.coords.latitude, longitude: cur.coords.longitude };
      setCoords(c);
      void saveLastLocation(c);
      return c;
    } catch (e: any) {
      setError(e?.message ?? 'Failed to get location.');
      return null;
    }
  }, []);

  useEffect(() => {
    void refresh();
  }, [refresh]);

  return { coords, granted, error, refresh };
}