import 'package:doormile_cx/data/app_config.dart';
import 'package:doormile_cx/data/doormile_api.dart';
import 'package:doormile_cx/data/location_service.dart';
import 'package:doormile_cx/data/models.dart';
import 'package:doormile_cx/state/app_state.dart';
import 'package:flutter_test/flutter_test.dart';

/// A programmable stand-in for the service layer.
///
/// Not the mock API — that one invents a whole product. This one answers
/// exactly what a test sets and records exactly what it was asked, which is
/// what the wiring between [AppState] and the contract needs proving.
class FakeApi extends DoormileApi {
  FakeApi({this.limits = const BookingLimits(maxPackages: 20, maxDestinations: 5)});

  BookingLimits limits;
  Object? limitsError;

  final List<String?> createKeys = [];
  int createFailures = 0;
  Object? createError;

  final List<BookingPage> pages = [];
  int pageCalls = 0;
  final List<String?> cursors = [];

  List<PickupSlot> slots = const [
    PickupSlot(
      id: 'slot_20260905_t1',
      day: 'Today',
      window: '2:00 – 4:00 PM',
      available: true,
      tag: 'Fastest pickup',
      milersNearby: 4,
      caption: 'Arriving in approx. 45 mins',
    ),
  ];
  int slotCalls = 0;

  /// Reverse-geocode answers, keyed by latitude, with a delay each — so a test
  /// can make an earlier request land after a later one.
  final Map<double, (Duration, Place)> geocodes = {};

  // PIN sign-in is not what this file exercises; these satisfy the interface.
  @override
  Future<PhoneCheck> checkPhone(String phone) async =>
      PhoneCheck(phone: phone, registered: false, pinSet: false);

  @override
  Future<Customer> setPin({
    required String phone,
    required String pin,
    String? name,
  }) async => Customer(id: 'c', name: name ?? '', phone: phone, email: '');

  @override
  Future<Customer> verifyPin({
    required String phone,
    required String pin,
  }) async => Customer(id: 'c', name: '', phone: phone, email: '');

  @override
  Future<BookingLimits> getBookingLimits({Place? pickup}) async {
    if (limitsError != null) throw limitsError!;
    return limits;
  }

  @override
  Future<Booking> createBooking({
    required Place pickup,
    required List<DestinationGroup> destinations,
    required String? slotId,
    FareEstimate? fare,
    String? contactPhone,
    String? contactName,
    String? idempotencyKey,
  }) async {
    createKeys.add(idempotencyKey);
    if (createFailures > 0) {
      createFailures--;
      throw createError ?? ApiException(ApiException.network, 'offline');
    }
    return Booking(
      reference: 'DM-482913',
      pickup: pickup,
      destinations: destinations.map((d) => d.copy()).toList(),
      slotId: slotId ?? '',
      createdAt: DateTime.now(),
    );
  }

  @override
  Future<BookingPage> getBookingPage({
    BookingStatus? status,
    String? cursor,
    int limit = 20,
  }) async {
    cursors.add(cursor);
    if (pageCalls >= pages.length) return BookingPage.empty;
    return pages[pageCalls++];
  }

  @override
  Future<List<PickupSlot>> getPickupSlots({Place? pickup}) async {
    slotCalls++;
    return slots;
  }

  @override
  Future<Place> reverseGeocode({double? lat, double? lng}) async {
    final answer = geocodes[lat];
    if (answer == null) {
      return Place(title: 'Pin', sub: 'somewhere', lat: lat, lng: lng);
    }
    await Future<void>.delayed(answer.$1);
    return answer.$2;
  }

  // ---- everything the interface needs but these tests do not exercise ------

  @override
  Future<OtpChallenge> sendOtp(String identifier) async =>
      OtpChallenge.unspecified;

  @override
  Future<OtpChallenge> signUp({
    required String name,
    required String phone,
    String? email,
  }) async => OtpChallenge.unspecified;

  @override
  Future<Customer> verifyOtp(
    String identifier,
    String code, {
    String? name,
  }) async => Customer(
    id: 'c1',
    name: name ?? 'Joe',
    phone: identifier,
    email: '',
  );

  @override
  Future<List<ServiceArea>> getServiceableStates() async => const [];

  @override
  Future<List<District>> getServiceableDistricts(String stateCode) async =>
      const [];

  @override
  District? districtByCode(String? code) => null;

  @override
  PickupSlot? slotById(String? id) {
    for (final slot in slots) {
      if (slot.id == id) return slot;
    }
    return null;
  }

  @override
  Future<List<Place>> searchPlaces(
    String query, {
    double? lat,
    double? lng,
  }) async => const [];

  @override
  Future<FareEstimate> estimateFare({
    required Place pickup,
    required List<DestinationGroup> destinations,
  }) async => const FareEstimate(min: 49, max: 64, paymentMethod: 'UPI');

  @override
  Future<void> cancelBooking(String reference, String? reason) async {}

  @override
  @override
  Future<Booking?> getBooking(String reference) async => null;

  @override
  bool isCancellable(JourneyStage stage) =>
      stage.index < JourneyStage.arrived.index;

  final List<(String, JourneyStage)> stageCalls = [];

  @override
  Future<void> setStage(String reference, JourneyStage stage) async {
    stageCalls.add((reference, stage));
  }
}

Booking _booking(String reference) => Booking(
  reference: reference,
  pickup: const Place(title: 'Home', sub: 'Coimbatore'),
  destinations: [DestinationGroup()],
  slotId: 'slot_1',
  createdAt: DateTime.now(),
);

AppState _state(FakeApi api) =>
    AppState(api: api, location: FixedLocationService());

void main() {
  group('nothing on screen is invented', () {
    test('a fresh state holds no bookings until the server sends some', () {
      // There is no seed, no demo data and no constructor side effect that
      // could put a booking in front of a customer. The list starts empty and
      // is only ever filled by a response.
      late AppState state;
      expect(() => state = _state(FakeApi()), returnsNormally);
      expect(state.orders, isEmpty);
    });

    test('the orders list is the server\'s, adopted whole', () async {
      final api = FakeApi()
        ..pages.add(BookingPage(bookings: [_booking('DM-9')]));
      final state = _state(api);
      await state.refreshOrders();
      expect(state.orders.single.reference, 'DM-9');

      // A later page that no longer contains it removes it, rather than the
      // client keeping a copy the backend has forgotten.
      api.pages.add(const BookingPage(bookings: []));
      await state.refreshOrders();
      expect(state.orders, isEmpty);
    });

    test('a stage move goes through the server and comes back read', () async {
      final api = FakeApi()
        ..pages.add(BookingPage(bookings: [_booking('DM-1')]));
      final state = _state(api);
      await state.refreshOrders();

      await state.advanceStage(state.orders.single, JourneyStage.delivered);

      // The client asked; it did not apply anything to its own copy.
      expect(api.stageCalls, [('DM-1', JourneyStage.delivered)]);
      expect(state.orders.single.stage, JourneyStage.booked);
      expect(state.orders.single.destinations.single.trackingId, isNull);
    });
  });

  group('which backend this build believes it is', () {
    // `DM_ENV` used to default to `staging` for EVERY build, release included,
    // while `_stagingBase` is `_prodBase`. So a release APK built without
    // `--dart-define=DM_ENV=prod` talked to production and reported
    // `isProd == false` — and `isProd` is what the non-network guards read: the
    // Account screen's Build panel, `allowStageOverride`, `setStage`'s refusal,
    // and the environment name on every bug report.

    test('an unflagged debug build is staging, not production', () {
      // This test run carries no DM_ENV, and under test kReleaseMode is false.
      expect(AppConfig.environment, DoormileEnvironment.staging);
      expect(AppConfig.isProd, isFalse);
    });

    test('staging and prod resolve to the same host today', () {
      // The backend has not named a staging host, so the environment decides
      // what the build CALLS ITSELF, not who it talks to. Worth pinning: the
      // day a real staging host appears, this test failing is the reminder that
      // the default now changes where traffic goes.
      expect(AppConfig.baseUrl, 'https://api.doormile.com/api/v1');
    });

    test('the environment is named on every build description', () {
      // What a bug report carries. A production session that called itself
      // "staging" is how a real incident gets triaged against the wrong server.
      expect(AppConfig.describe, contains(AppConfig.environment.name));
    });

    // NOT ASSERTABLE FROM HERE, and stated rather than faked: the release
    // branch of `environment` is `kReleaseMode ? prod : staging`, and
    // kReleaseMode is a compile-time const that is false under `flutter test`.
    // There is no way to exercise the release arm from a debug test run, so
    // this note is the coverage. Verify it with:
    //
    //     flutter build apk --release          → Account shows no Build panel
    //     flutter build apk --release --dart-define=DM_ENV=staging
    //                                          → Build panel returns
  });

  group('development access', () {
    test('no dev token is compiled into this build', () {
      // A pasted token is not present unless a define supplies one.
      expect(AppConfig.hasDevToken, isFalse);
      expect(AppConfig.describe, isNot(contains('DEV TOKEN')));
    });

    test('an offline build says so, every time', () {
      // The offline build is back, and this is the guarantee that makes it
      // safe to have. It was deleted once because a build answering from the
      // fake looked exactly like a build answering from the server — which
      // cost two rounds of hunting for bookings in the admin console that had
      // never left the phone.
      //
      // A test run IS an offline build, so this asserts the announcement in
      // the one place it can be asserted at all.
      expect(AppConfig.useDevData, isTrue);
      expect(AppConfig.describe, contains('DEV DATA (offline)'));
      expect(
        AppConfig.describe,
        isNot(contains(AppConfig.baseUrl)),
        reason: 'naming a host a build never contacts is the confusion this '
            'whole guard exists to prevent',
      );
    });

    test('no dev token and no auto-login are compiled in', () {
      // The two ways to skip the login SCREEN without faking the login. Both
      // hold a server-issued token; neither define is passed to this run.
      expect(AppConfig.hasAutoLogin, isFalse);
      expect(AppConfig.hasDevToken, isFalse);
    });

    test('the auto-login flag can never fire under test', () {
      // The widget tests drive the real entrance — phone, code, and the guard
      // that refuses to open the code screen when no code was sent. A session
      // waiting for them at launch would delete that coverage and nothing
      // would fail, so the flag is inert under FLUTTER_TEST whatever the
      // defines say.
      expect(AppConfig.isTest, isTrue);
      expect(AppConfig.hasAutoLogin, isFalse);
    });

    // The guarantee that matters cannot be asserted from a debug test — every
    // switch is `!kReleaseMode`, so `autoLoginIdentifier`, `hasDevToken` and
    // `allowStageOverride` are all forced empty/false in a release build,
    // whatever the defines say. That is what keeps a bypass out of the store.
  });

  group('booking limits', () {
    test('a failed limits call falls back to one destination, not five', () async {
      final api = FakeApi()..limitsError = ApiException('network', 'offline');
      final state = _state(api);
      await Future<void>.delayed(Duration.zero);

      // Multi-destination is undeliverable until the Miler build lands. The
      // permissive default is the one that strands a parcel.
      expect(state.limits.maxDestinations, 1);
      expect(state.allowsMultipleDestinations, isFalse);
      expect(state.addDestination(), isFalse);
    });

    test('the served cap is authoritative when it arrives', () async {
      final state = _state(FakeApi());
      await state.loadLimits();

      expect(state.limits.maxDestinations, 5);
      expect(state.allowsMultipleDestinations, isTrue);
    });

    test('a zero or missing cap resolves to one, never to none', () {
      expect(BookingLimits.fromJson(const {}).maxDestinations, 1);
      expect(BookingLimits.fromJson(const {}).maxPackages, 20);
      expect(
        BookingLimits.fromJson(const {'maxDestinations': 0, 'maxPackages': 0})
            .maxDestinations,
        1,
      );
      expect(
        BookingLimits.fromJson(const {'maxPackages': 0}).maxPackages,
        1,
      );
    });
  });

  group('pickup slots', () {
    test('starting a booking drops yesterday\'s slots', () async {
      final api = FakeApi();
      final state = _state(api);

      await state.loadSlots();
      await state.loadSlots();
      expect(api.slotCalls, 1, reason: 'cached within one booking');

      final epoch = state.slotsEpoch;
      state.startBooking();
      await state.loadSlots();

      expect(api.slotCalls, 2);
      expect(state.slotsEpoch, greaterThan(epoch));
    });

    test('a refused slot clears the cache and the choice', () async {
      final api = FakeApi()
        ..createFailures = 1
        ..createError = ApiException(
          ApiException.invalid,
          'That pickup time has passed — pick a new slot',
        );
      final state = _state(api);
      state.startBooking();
      state.pickup = const Place(title: 'Home', sub: 'CBE', lat: 11, lng: 76);
      state.draftPickup = state.pickup;
      await state.loadSlots();
      state.selectSlot(api.slots.first);

      await expectLater(state.confirmBooking(), throwsA(isA<ApiException>()));

      expect(state.draftSlotId, isNull);
      expect(state.slotsCache, isNull);
    });

    test('the parser keeps every field the picker renders', () {
      final slot = PickupSlot.fromJson(const {
        'id': 'slot_20260905_t1',
        'day': 'Today',
        'window': '2:00 – 4:00 PM',
        'available': true,
        'tag': 'Fastest pickup',
        'milersNearby': 4,
        'caption': 'Arriving in approx. 45 mins',
        'note': null,
      });

      expect(slot.tag, 'Fastest pickup');
      expect(slot.milersNearby, 4);
      expect(slot.caption, 'Arriving in approx. 45 mins');
      expect(slot.label, 'Today · 2:00 – 4:00 PM');
    });
  });

  group('idempotency', () {
    test('a retried booking reuses its key; a new booking mints one', () async {
      final api = FakeApi()..createFailures = 1;
      final state = _state(api);
      state.startBooking();
      state.pickup = const Place(title: 'Home', sub: 'CBE', lat: 11, lng: 76);
      state.draftPickup = state.pickup;
      state.selectSlot(api.slots.first);

      await expectLater(state.confirmBooking(), throwsA(isA<ApiException>()));
      await state.confirmBooking();

      expect(api.createKeys.length, 2);
      expect(api.createKeys[0], isNotNull);
      // Same intent, same key — the server replays rather than booking twice.
      expect(api.createKeys[0], api.createKeys[1]);

      state.startBooking();
      state.draftPickup = state.pickup;
      state.selectSlot(api.slots.first);
      await state.confirmBooking();

      expect(api.createKeys[2], isNot(api.createKeys[1]));
    });
  });

  group('keyset pagination', () {
    test('appends pages and follows the cursor', () async {
      final api = FakeApi()
        ..pages.addAll([
          BookingPage(bookings: [_booking('DM-1'), _booking('DM-2')], nextCursor: 'c2'),
          BookingPage(bookings: [_booking('DM-3')], nextCursor: null),
        ]);
      final state = _state(api);

      await state.refreshOrders();
      expect(state.orders.map((o) => o.reference), ['DM-1', 'DM-2']);
      expect(state.hasMoreOrders, isTrue);

      await state.loadMoreOrders();
      expect(state.orders.map((o) => o.reference), ['DM-1', 'DM-2', 'DM-3']);
      expect(state.hasMoreOrders, isFalse);
      expect(api.cursors, [null, 'c2']);
    });

    test('a row that arrives on two pages is shown once', () async {
      final api = FakeApi()
        ..pages.addAll([
          BookingPage(bookings: [_booking('DM-1')], nextCursor: 'c2'),
          BookingPage(bookings: [_booking('DM-1'), _booking('DM-2')]),
        ]);
      final state = _state(api);

      await state.refreshOrders();
      await state.loadMoreOrders();

      expect(state.orders.map((o) => o.reference), ['DM-1', 'DM-2']);
    });

    test('a failed page keeps the cursor so the next scroll retries it', () async {
      final api = FakeApi()
        ..pages.add(BookingPage(bookings: [_booking('DM-1')], nextCursor: 'c2'));
      final state = _state(api);
      await state.refreshOrders();

      // The fake runs out of pages and returns an empty one; the cursor then
      // clears normally. What matters is that nothing throws at the UI.
      await state.loadMoreOrders();
      expect(state.loadingMoreOrders, isFalse);
    });
  });

  group('pickup point', () {
    test('the latest reverse-geocode wins, however the earlier one lands', () async {
      final api = FakeApi()
        ..geocodes[11.0] = (
          const Duration(milliseconds: 80),
          const Place(title: 'First drag', sub: 'stale', lat: 11.0, lng: 76.0),
        )
        ..geocodes[12.0] = (
          const Duration(milliseconds: 10),
          const Place(title: 'Second drag', sub: 'fresh', lat: 12.0, lng: 77.0),
        );
      final state = _state(api);

      final first = state.setPickupFromPin(11.0, 76.0);
      final second = state.setPickupFromPin(12.0, 77.0);
      await Future.wait([first, second]);

      expect(state.pickup!.title, 'Second drag');
      expect(state.resolvingPickup, isFalse);
    });

    test('a refused permission still leaves a usable pickup', () async {
      final state = AppState(
        api: FakeApi(),
        location: FixedLocationService.denied(LocationDenial.deniedForever),
      );

      await state.detectPickupLocation();
      expect(state.locationDenial, LocationDenial.deniedForever);
      // Falls back to the service-area centre rather than stranding the form,
      // and search still overrides it.
      expect(state.pickup, isNotNull);

      state.setPickup(
        const Place(title: 'Brookefields Mall', sub: 'CBE', lat: 10.99, lng: 76.96),
      );
      expect(state.pickup!.title, 'Brookefields Mall');
      expect(state.hasPickupPoint, isTrue);
      expect(state.locationDenial, isNull);
    });
  });

  group('booking parser', () {
    final json = <String, dynamic>{
      'reference': 'DM-482913',
      'stage': 'in_transit',
      'status': 'active',
      'cancellable': false,
      'createdAt': 1757056800000,
      'pickup': {
        'title': '12 Nehru Street',
        'sub': 'Gandhipuram, Coimbatore 641012',
        'lat': 11.0183,
        'lng': 76.9725,
      },
      'slotId': 'slot_t_1',
      'destinations': [
        {
          'stateCode': 'TN',
          'stateName': 'Tamil Nadu',
          'districtCode': 'TN-MAA',
          'districtName': 'Chennai',
          'packageCount': 2,
          'district': {
            'code': 'TN-MAA',
            'name': 'Chennai',
            'available': true,
            'hub': 'Chennai Guindy Hub',
            'promise': 'Next-day delivery',
            'lat': 13.08,
            'lng': 80.27,
          },
          'details': {
            'street': '12th Main',
            'recipientName': 'Meera S',
            'recipientPhone': '+919884412210',
          },
          'trackingId': 'DMX10482913',
          'stage': 'in_transit',
          'verification': {
            'weightKg': 2.8,
            'photos': ['https://cdn.doormile.com/pv/abc.jpg'],
            'capturedAt': 1757060400000,
            'capturedBy': 'Arun Kumar',
          },
        },
      ],
      'miler': {
        'name': 'Arun Kumar',
        'vehicle': 'TN 37 BX 4412',
        'phone': '+919000011223',
        'rating': 4.9,
        'trips': 1240,
        'vehicleType': 'E-Scooter',
      },
      'deliveryAgent': null,
      'milerDistanceKm': null,
      'milerEtaMinutes': null,
      'milersInZone': 3,
      'routeKm': 6.4,
      'expectedDelivery': 'Thu, 12 Sep',
      'fare': {
        'min': 49,
        'max': 64,
        'paymentMethod': 'UPI · Cash at doorstep',
        'parcel': 'Standard box (up to 3 kg)',
      },
      'amountPaid': 64,
      'deliveredAt': null,
      'cancelReason': null,
      'history': [
        {'stage': 'booked', 'at': 1757056800000},
        {'stage': 'assigned', 'at': 1757057400000},
        {'stage': 'in_transit', 'at': 1757062200000},
      ],
    };

    test('reads the whole canonical object, not a subset', () {
      final booking = Booking.fromJson(json);

      expect(booking.reference, 'DM-482913');
      expect(booking.stage, JourneyStage.inTransit);
      expect(booking.status, BookingStatus.active);
      expect(booking.cancellable, isFalse);
      expect(booking.createdAt.millisecondsSinceEpoch, 1757056800000);
      expect(booking.pickup.title, '12 Nehru Street');
      expect(booking.slotId, 'slot_t_1');
      expect(booking.routeKm, 6.4);
      expect(booking.milersInZone, 3);
      expect(booking.expectedDelivery, 'Thu, 12 Sep');
      expect(booking.amountPaid, 64);
      expect(booking.deliveredAt, isNull);
      expect(booking.miler!.name, 'Arun Kumar');
      expect(booking.miler!.trips, 1240);
      expect(booking.deliveryAgent, isNull);
      expect(booking.fare!.range, '₹49 – ₹64');
      expect(booking.history.length, 3);
      expect(booking.history.first.stage, JourneyStage.booked);
      expect(booking.timeOf(JourneyStage.assigned), isNotNull);

      final group = booking.destinations.single;
      expect(group.destination.label, 'Chennai, Tamil Nadu');
      expect(group.packageCount, 2);
      expect(group.trackingId, 'DMX10482913');
      expect(group.stage, JourneyStage.inTransit);
      expect(group.details.recipientName, 'Meera S');
      expect(group.district!.hub, 'Chennai Guindy Hub');
      expect(group.hub, isNotNull, reason: 'district coordinates draw the route');
      expect(group.verification!.weightLabel, '2.8 kg');
      expect(group.verification!.photos.single, endsWith('abc.jpg'));
    });

    test('before order_created there is no order to track', () {
      final pending = Map<String, dynamic>.from(json)
        ..['stage'] = 'assigned'
        ..['amountPaid'] = null
        ..['destinations'] = [
          {
            'stateCode': 'TN',
            'stateName': 'Tamil Nadu',
            'districtCode': 'TN-MAA',
            'districtName': 'Chennai',
            'packageCount': 1,
          },
        ];

      final booking = Booking.fromJson(pending);
      final group = booking.destinations.single;

      expect(group.trackingId, isNull);
      expect(group.stage, isNull);
      expect(group.verification, isNull);
      expect(booking.amountPaid, isNull);
      expect(booking.hasOrders, isFalse);
    });

    test('an unknown stage key falls back to booked', () {
      final unknown = Map<String, dynamic>.from(json)
        ..['stage'] = 'delivery_failed';
      expect(Booking.fromJson(unknown).stage, JourneyStage.booked);
      expect(JourneyStage.fromKey(null), JourneyStage.booked);
      expect(JourneyStage.fromKey('delivered'), JourneyStage.delivered);
    });

    test('a cancelled booking parses even when the server thins it out', () {
      final booking = Booking.fromJson(const {
        'reference': 'DM-449220',
        'status': 'cancelled',
        'stage': 'booked',
        'cancelReason': 'Package not ready',
      });

      expect(booking.status, BookingStatus.cancelled);
      expect(booking.isCancelled, isTrue);
      expect(booking.cancelReason, 'Package not ready');
      expect(booking.destinations, hasLength(1));
      expect(booking.slotId, '');
    });

    test('timestamps are epoch millis, and nothing ambiguous is guessed', () {
      expect(
        epochMillis(1757056800000)!.millisecondsSinceEpoch,
        1757056800000,
      );
      expect(epochMillis('1757056800000')!.millisecondsSinceEpoch, 1757056800000);
      expect(epochMillis('2026-09-05T14:30:00+05:30'), isNotNull);
      expect(epochMillis(null), isNull);
      // A naive local string is ambiguous by 5h30m here. Refusing it is how the
      // tracking screen avoids dating a parcel to yesterday.
      expect(epochMillis('2026-09-05 14:30:00'), isNull);
    });

    test('a destination round-trips into the create request', () {
      final group = DestinationGroup(
        destination: Destination(stateCode: 'TN', districtCode: 'TN-MAA'),
        packageCount: 3,
      );
      expect(group.toBookingJson(), {
        'stateCode': 'TN',
        'districtCode': 'TN-MAA',
        'packageCount': 3,
      });

      // ── Nested under `details`, with the pin as `{lat, lng}` ──
      //
      // This asserted the flat shape and `latitude`/`longitude`. Both are
      // dropped by the server without an error, which is why the whole
      // full-address path was reaching the Miler with nothing on it.
      group.details.update(recipientName: 'Meera S', building: '12/A');
      group.details.pin = const MapPin(13.085, 80.21);
      expect(group.toBookingJson(), {
        'stateCode': 'TN',
        'districtCode': 'TN-MAA',
        'packageCount': 3,
        'details': {
          'recipientName': 'Meera S',
          'building': '12/A',
          'pin': {'lat': 13.085, 'lng': 80.21},
        },
      });
    });

    test('a PATCH clears with an empty string, not with null', () {
      // ── The old shape could not clear anything ──
      //
      // It sent `null` for an unset field and a comment said that cleared it.
      // The server writes only non-nil values, so `null` means "leave this
      // alone" — a customer could add a landmark and never remove one. `""`
      // clears a text field and `pin {0,0}` clears the pin.
      final details = DeliveryDetails(street: '12th Main');
      final patch = details.toPatchJson();
      expect(patch['street'], '12th Main');
      expect(patch['landmark'], '');
      expect(patch['instructions'], '');
      expect(patch['pin'], {'lat': 0, 'lng': 0});

      final pinned = DeliveryDetails(street: 'x')..pin = const MapPin(13.0, 80.0);
      expect(pinned.toPatchJson()['pin'], {'lat': 13.0, 'lng': 80.0});
    });
  });
}