import 'package:flutter_test/flutter_test.dart';

import 'package:emergency/services/country_code_sources/country_code_source.dart';
import 'package:emergency/services/location_service.dart';

/// Einfache manuelle Fake-Quelle statt Mocking-Package (siehe AP4-Vorgabe:
/// kein neues Mocking-Package einführen).
class _FakeSource implements CountryCodeSource {
  _FakeSource(this._result);

  final String? _result;
  int callCount = 0;

  @override
  Future<String?> resolve() async {
    callCount++;
    return _result;
  }
}

class _FakeCache implements CountryCodeCache {
  _FakeCache({String? initial}) : _stored = initial;

  String? _stored;
  int resolveCallCount = 0;
  final List<String> savedCodes = [];

  @override
  Future<String?> resolve() async {
    resolveCallCount++;
    return _stored;
  }

  @override
  Future<void> save(String isoCode) async {
    savedCodes.add(isoCode);
    _stored = isoCode;
  }
}

/// Fake für die manuelle Auswahl (AP6). Ohne explizite Injektion würde
/// `LocationService()` intern ein echtes `ManualCountryCodeSource` (und damit
/// `shared_preferences`) ansprechen, was in diesen reinen Unit-Tests (kein
/// `TestWidgetsFlutterBinding.ensureInitialized()`/Mock-Setup) nicht
/// notwendig sein soll – die bestehenden SIM/GPS/Cache-Tests sollen von der
/// manuellen Auswahl unbeeinflusst bleiben.
class _FakeManualSource implements ManualCountryCodeStore {
  _FakeManualSource([this._result]);

  final String? _result;
  int resolveCallCount = 0;
  final List<String?> savedCodes = [];

  @override
  Future<String?> resolve() async {
    resolveCallCount++;
    return _result;
  }

  @override
  Future<void> save(String? isoCode) async {
    savedCodes.add(isoCode);
  }
}

void main() {
  group('LocationService.resolveCountryCode()', () {
    test(
      'SIM liefert Ergebnis -> wird verwendet, GPS/Cache werden nicht abgefragt, '
      'Ergebnis wird gecacht',
      () async {
        final sim = _FakeSource('DE');
        final gps = _FakeSource('FR');
        final cache = _FakeCache(initial: 'US');
        final service = LocationService(
          simSource: sim,
          gpsSource: gps,
          cacheSource: cache,
          manualSource: _FakeManualSource(),
        );

        final result = await service.resolveCountryCode();

        expect(result, 'DE');
        expect(sim.callCount, 1);
        expect(gps.callCount, 0);
        expect(cache.resolveCallCount, 0);
        expect(cache.savedCodes, ['DE']);
      },
    );

    test(
      'SIM liefert null, GPS liefert Ergebnis -> wird verwendet, Cache wird nicht '
      'gelesen, aber beschrieben',
      () async {
        final sim = _FakeSource(null);
        final gps = _FakeSource('FR');
        final cache = _FakeCache(initial: 'US');
        final service = LocationService(
          simSource: sim,
          gpsSource: gps,
          cacheSource: cache,
          manualSource: _FakeManualSource(),
        );

        final result = await service.resolveCountryCode();

        expect(result, 'FR');
        expect(sim.callCount, 1);
        expect(gps.callCount, 1);
        expect(cache.resolveCallCount, 0);
        expect(cache.savedCodes, ['FR']);
      },
    );

    test('SIM und GPS liefern null, Cache liefert Ergebnis -> wird verwendet', () async {
      final sim = _FakeSource(null);
      final gps = _FakeSource(null);
      final cache = _FakeCache(initial: 'US');
      final service = LocationService(
        simSource: sim,
        gpsSource: gps,
        cacheSource: cache,
        manualSource: _FakeManualSource(),
      );

      final result = await service.resolveCountryCode();

      expect(result, 'US');
      expect(cache.resolveCallCount, 1);
      // Kein erneutes Schreiben, da das Ergebnis ja bereits aus dem Cache kam.
      expect(cache.savedCodes, isEmpty);
    });

    test('Alle drei automatischen Quellen liefern null -> Ergebnis ist null', () async {
      final sim = _FakeSource(null);
      final gps = _FakeSource(null);
      final cache = _FakeCache();
      final service = LocationService(
        simSource: sim,
        gpsSource: gps,
        cacheSource: cache,
        manualSource: _FakeManualSource(),
      );

      final result = await service.resolveCountryCode();

      expect(result, isNull);
      expect(cache.savedCodes, isEmpty);
    });

    test(
      'manuelle Auswahl gesetzt -> hat Vorrang vor SIM/GPS/Cache, die anderen '
      'Quellen werden gar nicht erst abgefragt',
      () async {
        final sim = _FakeSource('DE');
        final gps = _FakeSource('FR');
        final cache = _FakeCache(initial: 'US');
        final manual = _FakeManualSource('IT');
        final service = LocationService(
          simSource: sim,
          gpsSource: gps,
          cacheSource: cache,
          manualSource: manual,
        );

        final result = await service.resolveCountryCode();

        expect(result, 'IT');
        expect(sim.callCount, 0);
        expect(gps.callCount, 0);
        expect(cache.resolveCallCount, 0);
        // Die manuelle Auswahl wird bewusst nicht in den automatischen Cache
        // geschrieben (getrennte Mechanismen, siehe Doc-Kommentar).
        expect(cache.savedCodes, isEmpty);
      },
    );

    test('keine manuelle Auswahl gesetzt -> Kette fällt normal auf SIM zurück', () async {
      final sim = _FakeSource('DE');
      final gps = _FakeSource('FR');
      final cache = _FakeCache(initial: 'US');
      final manual = _FakeManualSource(null);
      final service = LocationService(
        simSource: sim,
        gpsSource: gps,
        cacheSource: cache,
        manualSource: manual,
      );

      final result = await service.resolveCountryCode();

      expect(result, 'DE');
      expect(manual.resolveCallCount, 1);
    });
  });

  group('LocationService.setManualCountryCode()', () {
    test('delegiert an die manuelle Quelle', () async {
      final manual = _FakeManualSource();
      final service = LocationService(
        simSource: _FakeSource(null),
        gpsSource: _FakeSource(null),
        cacheSource: _FakeCache(),
        manualSource: manual,
      );

      await service.setManualCountryCode('IT');
      await service.setManualCountryCode(null);

      expect(manual.savedCodes, ['IT', null]);
    });
  });
}