import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';

/// Supplies the device's *approximate* location (or null when unavailable or
/// denied). Behind an interface so the UI is fakeable in tests and the concrete
/// platform code stays at the composition root. The caller immediately reduces
/// the result to a low-precision geohash — a precise fix never leaves the device.
abstract interface class CoarseLocationProvider {
  Future<({double lat, double lon})?> currentCoarseLatLon();
}

/// Platform-channel implementation backed by Android's own LocationManager —
/// deliberately no Google Play Services, so the APK stays free of proprietary
/// classes (F-Droid inclusion). The native side handles the permission prompt,
/// a coarse single fix with a timeout, and a last-known-position fallback.
/// Returns null on any denial/error rather than throwing, so the UI can
/// degrade quietly. Android only; other platforms return null.
class NativeCoarseLocation implements CoarseLocationProvider {
  const NativeCoarseLocation();

  static const _channel = MethodChannel('org.comunes.tane/coarse_location');

  @override
  Future<({double lat, double lon})?> currentCoarseLatLon() async {
    if (defaultTargetPlatform != TargetPlatform.android) return null;
    try {
      // Safety net over the native 12s fix timeout; the permission prompt can
      // legitimately keep the call open for a while, hence the wide margin.
      final result = await _channel
          .invokeMapMethod<String, double>('getCoarseLatLon')
          .timeout(const Duration(seconds: 60));
      final lat = result?['lat'];
      final lon = result?['lon'];
      if (lat == null || lon == null) return null;
      return (lat: lat, lon: lon);
    } catch (_) {
      return null; // denied, timeout, channel error…
    }
  }
}