import 'package:flutter_test/flutter_test.dart';
import 'package:nearle_pos/data/datasources/local_store.dart';
import 'package:nearle_pos/data/datasources/seed_data.dart';
import 'package:nearle_pos/data/local/app_database.dart';
import 'package:nearle_pos/data/remote/order_transport.dart';
import 'package:nearle_pos/data/remote/simulated_catalogue_source.dart';
import 'package:nearle_pos/data/repositories/customer_repository_impl.dart';
import 'package:nearle_pos/data/repositories/product_repository_impl.dart';
import 'package:nearle_pos/data/repositories/sync_repository_impl.dart';
import 'package:nearle_pos/data/repositories/transaction_repository_impl.dart';
import 'package:nearle_pos/domain/entities/cart.dart';
import 'package:nearle_pos/domain/entities/customer.dart';
import 'package:nearle_pos/domain/entities/transaction.dart';
import 'package:nearle_pos/domain/usecases/checkout_sale.dart';

/// A shopper who signs up at the till has to reach the back office in their
/// own right. Before the customer outbox they only ever travelled as three
/// fields riding along on a bill — so somebody who registered and then bought
/// nothing, or whose bill was still queued, existed on one terminal and
/// nowhere else.
void main() {
  late LocalStore store;
  late CustomerRepositoryImpl customers;
  late CheckoutSale checkout;

  setUpAll(() {
    LocalStore.registerSeed(
      products: SeedData.products,
      customers: SeedData.customers,
    );
  });

  setUp(() async {
    store = LocalStore.instance;
    await store.reset(withCatalogue: true);

    customers = CustomerRepositoryImpl(store);
    checkout = CheckoutSale(
      productRepository: ProductRepositoryImpl(store),
      customerRepository: customers,
      transactionRepository: TransactionRepositoryImpl(store),
    );
  });

  tearDownAll(() => AppDatabase.instance.close());

  SyncRepositoryImpl syncWith(OrderTransport transport) => SyncRepositoryImpl(
        store,
        SimulatedCatalogueSource(isOffline: () => false),
        transport,
      );

  Future<Customer> register(String mobile, {String name = 'Meena'}) =>
      customers.create(Customer(id: '', name: name, mobile: mobile));

  group('identity', () {
    test('the same mobile produces the same id on any terminal', () {
      // The whole point. A hundred tills mint ids without talking to each
      // other, so the id has to be a function of the shopper, not of chance.
      expect(
        Customer.idForMobile('9840012345'),
        Customer.idForMobile('9840012345'),
      );
    });

    test('formatting does not create a second shopper', () {
      final plain = Customer.idForMobile('9840012345');
      expect(Customer.idForMobile('+91 98400 12345'), plain);
      expect(Customer.idForMobile('98400-12345'), plain);
    });

    test('the country code and the trunk prefix are stripped', () {
      expect(Customer.normaliseMobile('+91 98400 12345'), '9840012345');
      expect(Customer.normaliseMobile('098400 12345'), '9840012345');
      expect(Customer.normaliseMobile('9840012345'), '9840012345');
    });

    test('a number the rule was not written for is left alone', () {
      // Mangling something unrecognised is worse than storing it verbatim: a
      // wrongly-trimmed number silently merges two different shoppers.
      expect(Customer.normaliseMobile('4155550123'), '4155550123');
      expect(Customer.normaliseMobile('12345'), '12345');
      // Twelve digits that do not start with the Indian country code.
      expect(Customer.normaliseMobile('442071234567'), '442071234567');
    });

    test('different shoppers get different ids', () {
      expect(
        Customer.idForMobile('9840012345'),
        isNot(Customer.idForMobile('9840012346')),
      );
    });

    test('a registration is keyed on the number, not on chance', () async {
      final created = await register('+91 98400 12345');
      expect(created.id, Customer.idForMobile('9840012345'));
      expect(created.mobile, '9840012345');
    });
  });

  group('the outbox', () {
    test('a shopper registered at the till is queued', () async {
      final before = await store.catalogue.unsyncedCustomerCount();
      await register('9840012345');
      expect(await store.catalogue.unsyncedCustomerCount(), before + 1);
    });

    test('a shopper who buys nothing still goes up', () async {
      // The case that used to be lost entirely: no bill, so nothing to ride.
      final created = await register('9840012345');

      final transport = _RecordingTransport();
      final outcome = await syncWith(transport).syncCustomers();

      expect(outcome.uploaded, greaterThanOrEqualTo(1));
      expect(transport.sentIds, contains(created.id));
    });

    test('shoppers that came from the back office are not posted back',
        () async {
      // The seed catalogue arrives as an import. Sending it straight back
      // would be a round trip telling the server what it just told us.
      final imported = store.customers.map((c) => c.id).toSet();
      expect(imported, isNotEmpty, reason: 'the fixture needs seeded shoppers');

      final pending = await store.catalogue.unsyncedCustomers(limit: 500);
      expect(
        pending.map((c) => c.id).toSet().intersection(imported),
        isEmpty,
      );
    });

    test('only the ids the back office names are marked sent', () async {
      final kept = await register('9840012345', name: 'Meena');
      final dropped = await register('9840099999', name: 'Ravi');

      // Silence about a row is not acceptance of it.
      final transport = _RecordingTransport(
        accept: (ids) => ids.where((id) => id == kept.id).toList(),
      );
      await syncWith(transport).syncCustomers();

      final stillPending =
          (await store.catalogue.unsyncedCustomers(limit: 500))
              .map((c) => c.id)
              .toSet();

      expect(stillPending, contains(dropped.id));
      expect(stillPending, isNot(contains(kept.id)));
    });

    test('a batch nobody accepts stops rather than looping for ever',
        () async {
      await register('9840012345');

      final transport = _RecordingTransport(accept: (_) => const []);
      final outcome = await syncWith(transport).syncCustomers();

      expect(outcome.isSuccess, isFalse);
      expect(outcome.isRetryable, isFalse);
      expect(transport.calls, 1, reason: 'the same page must not be re-read');
    });

    test('an unreachable back office leaves everyone pending', () async {
      final created = await register('9840012345');

      final outcome = await syncWith(_FailingTransport()).syncCustomers();

      expect(outcome.isSuccess, isFalse);
      expect(outcome.uploaded, 0);
      expect(
        (await store.catalogue.unsyncedCustomers(limit: 500))
            .map((c) => c.id),
        contains(created.id),
      );
    });
  });

  group('a sale does not disturb the outbox', () {
    /// Rings a bill for [customer] so loyalty movement is written.
    Future<void> ringSaleFor(Customer customer) async {
      final product = store.products.first;
      final cart = Cart(
        lines: [CartLine(product: product, quantity: 1)],
        customer: customer,
      );
      await checkout(
        cart: cart,
        payments: [
          PaymentSplit(method: PaymentMethod.cash, amount: cart.grandTotal),
        ],
        cashierName: 'Suriya',
        terminalId: 'T4A9',
      );
    }

    test('a sale does not re-queue a shopper already sent', () async {
      final created = await register('9840012345');
      await syncWith(_RecordingTransport()).syncCustomers();
      expect(await store.catalogue.unsyncedCustomerCount(), 0);

      await ringSaleFor(created);

      // A sale writes the shopper's new points and spend. Done as an upsert
      // that replaces the row, every column absent from it — sync_status
      // included — would silently revert to its schema default.
      expect(
        await store.catalogue.unsyncedCustomerCount(),
        0,
        reason: 'loyalty movement is not a registration change',
      );
    });

    test('a sale still moves the loyalty figures', () async {
      // Guards the fix above from being "achieved" by not writing at all.
      final created = await register('9840012345');
      await ringSaleFor(created);

      final after = await store.catalogue.customerById(created.id);
      expect(after!.visitCount, 1);
      expect(after.lifetimeSpend, greaterThan(0));
      expect(after.lastVisitAt, isNotNull);
    });

    test('a sale does not overwrite a profile', () async {
      final created = await register('9840012345', name: 'Meena');
      await ringSaleFor(created);

      final after = await store.catalogue.customerById(created.id);
      expect(after!.name, 'Meena');
      expect(after.mobile, '9840012345');
    });
  });
}

/// Accepts what it is told to and remembers what it saw.
class _RecordingTransport implements OrderTransport {
  /// Heartbeats are irrelevant to what these tests assert; recorded only so the
  /// fake satisfies the interface.
  @override
  Future<void> publishHealth(String payload) async {
    healthBeats.add(payload);
  }

  final List<String> healthBeats = [];

  _RecordingTransport({List<String> Function(List<String> ids)? accept})
      : accept = accept ?? ((ids) => ids);

  final List<String> Function(List<String> ids) accept;

  final sentIds = <String>[];
  int calls = 0;

  @override
  String get label => 'Recording';

  @override
  bool get isConnected => true;

  @override
  Stream<DownlinkMessage> get downlink => const Stream.empty();

  @override
  Stream<bool> get connectionState => const Stream.empty();

  @override
  Future<void> connect() async {}

  @override
  Future<PushReceipt> pushOrders(List<Map<String, Object?>> orders) async =>
      PushReceipt(accepted: orders.map((o) => o['id']! as String).toList());

  @override
  Future<PushReceipt> pushCustomers(
    List<Map<String, Object?>> customers,
  ) async {
    calls++;
    final ids = customers.map((c) => c['id']! as String).toList();
    sentIds.addAll(ids);
    return PushReceipt(accepted: accept(ids));
  }

  @override
  Future<void> dispose() async {}
}

class _FailingTransport implements OrderTransport {
  /// Heartbeats are irrelevant to what these tests assert; recorded only so the
  /// fake satisfies the interface.
  @override
  Future<void> publishHealth(String payload) async {
    healthBeats.add(payload);
  }

  final List<String> healthBeats = [];

  @override
  String get label => 'Failing';

  @override
  bool get isConnected => false;

  @override
  Stream<DownlinkMessage> get downlink => const Stream.empty();

  @override
  Stream<bool> get connectionState => const Stream.empty();

  @override
  Future<void> connect() async {}

  @override
  Future<PushReceipt> pushOrders(List<Map<String, Object?>> orders) async =>
      throw const TransportException('unreachable');

  @override
  Future<PushReceipt> pushCustomers(
    List<Map<String, Object?>> customers,
  ) async =>
      throw const TransportException('unreachable');

  @override
  Future<void> dispose() async {}
}