import 'package:flutter_test/flutter_test.dart';
import 'package:nearle_pos/data/datasources/local_store.dart';
import 'package:nearle_pos/data/datasources/remote_catalogue_source.dart';
import 'package:nearle_pos/data/datasources/seed_data.dart';
import 'package:nearle_pos/data/remote/simulated_order_transport.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/shift_report.dart';
import 'package:nearle_pos/domain/entities/sync_event.dart';
import 'package:nearle_pos/domain/entities/transaction.dart';
import 'package:nearle_pos/domain/usecases/checkout_sale.dart';

/// Guards the boundary between a live bill and a stored one.
///
/// Every figure a shop is paid on survives a write to SQLite and a read back
/// out of it. These are regressions: the read path used to rebuild a bill from
/// its lines alone, silently dropping bill-level discounts and loyalty.
void main() {
  late LocalStore store;
  late ProductRepositoryImpl products;
  late CustomerRepositoryImpl customers;
  late TransactionRepositoryImpl transactions;
  late CheckoutSale checkout;

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

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

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

  /// A Gold member (5% tier discount) holding 400 points.
  Future<Customer> goldMember() async {
    final created = await customers.create(const Customer(
      id: 'ignored',
      name: 'Gold Shopper',
      mobile: '9000000001',
    ),);
    return customers.update(
      created.copyWith(loyaltyPoints: 400, lifetimeSpend: 60000),
    );
  }

  group('order round trip', () {
    test('bill discount, loyalty and total survive a write and read back',
        () async {
      final milk = (await products.findByBarcode('8901234500011'))!;
      final member = await goldMember();

      // 10 x 62.00 = 620 subtotal, less 5% tier (31) and a flat 50 = 81,
      // less 40 points at 0.25 = 10. Payable 529.
      final cart = Cart(
        lines: [CartLine(product: milk, quantity: 10)],
        customer: member,
        billDiscount: const Discount(type: DiscountType.flat, value: 50),
        pointsRedeemed: 40,
      );
      expect(cart.grandTotal, 529);
      expect(cart.billDiscountTotal, 81);

      final result = await checkout(
        cart: cart,
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 529, tendered: 529),
        ],
        cashierName: 'Divya',
      );

      final stored = (await transactions.history()).single;

      expect(stored.total, result.transaction.total,
          reason: 'the figure charged must not move in storage',);
      expect(stored.total, 529);
      expect(stored.cart.billDiscountTotal, 81);
      expect(stored.cart.loyaltyRedemptionValue, 10);
      expect(stored.cart.pointsRedeemed, 40);
      expect(stored.cart.taxAmount, cart.taxAmount);
      expect(stored.cart.subtotal, 620);
    });

    test('a rebuilt bill does not re-apply the tier discount', () async {
      final milk = (await products.findByBarcode('8901234500011'))!;
      final member = await goldMember();

      final cart = Cart(
        lines: [CartLine(product: milk, quantity: 10)],
        customer: member,
      );
      // 620 less the 5% tier discount only.
      expect(cart.grandTotal, 589);

      await checkout(
        cart: cart,
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 589, tendered: 600),
        ],
        cashierName: 'Divya',
      );

      final stored = (await transactions.history()).single;
      expect(stored.cart.billDiscountTotal, 31);
      expect(stored.total, 589);
    });

    test('the shift report reads back the amount actually charged', () async {
      final milk = (await products.findByBarcode('8901234500011'))!;
      final member = await goldMember();

      await checkout(
        cart: Cart(
          lines: [CartLine(product: milk, quantity: 10)],
          customer: member,
          billDiscount: const Discount(type: DiscountType.flat, value: 50),
          pointsRedeemed: 40,
        ),
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 529, tendered: 529),
        ],
        cashierName: 'Divya',
      );

      final report = ShiftReport.fromTransactions(
        transactions: await transactions.history(),
        businessDate: DateTime.now(),
        terminalId: 'TERM-01',
        cashierName: 'Divya',
      );

      expect(report.grossSales, 529);
      expect(report.discountGiven, 81);
      expect(report.loyaltyPointsRedeemed, 40);
    });

    test('the bill is stamped with the operator who rang it', () async {
      final milk = (await products.findByBarcode('8901234500011'))!;

      await checkout(
        cart: Cart(lines: [CartLine(product: milk, quantity: 1)]),
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 62, tendered: 100),
        ],
        cashierName: 'Rahul',
        terminalId: 'TERM-07',
      );

      final stored = (await transactions.history()).single;
      expect(stored.cashierName, 'Rahul');
      expect(stored.terminalId, 'TERM-07');
    });
  });

  group('stock safety', () {
    test('a resumed parked bill is re-checked against live stock', () async {
      final milk = (await products.findByBarcode('8901234500011'))!;

      await transactions.park(ParkedBill(
        id: 'p-1',
        cart: Cart(lines: [CartLine(product: milk, quantity: milk.stock)]),
        parkedAt: DateTime.now(),
      ),);

      // The same stock is sold on another bill in the meantime.
      await products.decrementStock({milk.id: milk.stock});

      final resumed = (await transactions.parkedBills()).single;

      await expectLater(
        checkout(
          cart: resumed.cart,
          payments: [
            PaymentSplit(
              method: PaymentMethod.cash,
              amount: resumed.cart.grandTotal,
              tendered: resumed.cart.grandTotal,
            ),
          ],
          cashierName: 'Divya',
        ),
        throwsA(isA<CheckoutFailure>()),
      );

      expect(await transactions.history(), isEmpty);
    });

    test('a re-import does not restore stock already sold', () async {
      final milk = (await products.findByBarcode('8901234500011'))!;
      final opening = milk.stock;

      await checkout(
        cart: Cart(lines: [CartLine(product: milk, quantity: 4)]),
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 248, tendered: 250),
        ],
        cashierName: 'Divya',
      );
      expect((await products.findByBarcode('8901234500011'))!.stock,
          opening - 4,);

      // The morning catalogue is pulled again before the bills went up.
      await store.importCatalogue(
        products: SeedData.products(),
        customers: SeedData.customers(),
        revision: 'seed-2',
        at: DateTime.now(),
      );

      expect(
        (await products.findByBarcode('8901234500011'))!.stock,
        opening - 4,
        reason: 'units sold on unsynced bills must not reappear on the shelf',
      );
    });
  });

  group('atomicity', () {
    test('nothing is persisted when the sale cannot be completed', () async {
      final milk = (await products.findByBarcode('8901234500011'))!;
      final opening = milk.stock;

      // A customer that was never written to the database.
      const ghost = Customer(id: 'missing', name: 'Ghost', mobile: '9999999999');

      await expectLater(
        checkout(
          cart: Cart(
            lines: [CartLine(product: milk, quantity: 2)],
            customer: ghost,
          ),
          payments: const [
            PaymentSplit(method: PaymentMethod.cash, amount: 124, tendered: 124),
          ],
          cashierName: 'Divya',
        ),
        throwsA(isA<CheckoutFailure>()),
      );

      expect(await transactions.history(), isEmpty,
          reason: 'a failed sale must not leave a bill behind',);
      expect((await products.findByBarcode('8901234500011'))!.stock, opening,
          reason: 'a failed sale must not consume stock',);
    });

    test('concurrent checkouts never share an invoice sequence', () async {
      final numbers = await Future.wait(
        List.generate(25, (_) => transactions.nextInvoiceSequence()),
      );
      expect(numbers.toSet().length, numbers.length);
    });
  });

  group('end of day', () {
    test('the archived day totals match what was charged', () async {
      final sync = SyncRepositoryImpl(
        store,
        RemoteCatalogueSource(isOffline: () => false),
        SimulatedOrderTransport(isOffline: () => false),
      );

      final milk = (await products.findByBarcode('8901234500011'))!;
      final member = await goldMember();

      await checkout(
        cart: Cart(
          lines: [CartLine(product: milk, quantity: 10)],
          customer: member,
          billDiscount: const Discount(type: DiscountType.flat, value: 50),
          pointsRedeemed: 40,
        ),
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 529, tendered: 529),
        ],
        cashierName: 'Divya',
      );

      final outcome = await sync.syncOrders();
      expect(outcome.uploaded, 1);
      expect(await sync.unsyncedCount(), 0);

      // Synced bills are deleted, so today's figures now come from the archive.
      // A wrong row here is permanent — there is nothing left to recompute from.
      final report = await sync.todayReport(
        terminalId: 'TERM-01',
        cashierName: 'Divya',
      );

      expect(report.billCount, 1);
      expect(report.grossSales, 529);
      expect(report.discountGiven, 81);
      expect(report.loyaltyPointsRedeemed, 40);
      expect(report.paymentBreakdown[PaymentMethod.cash], 529);
    });
  });

  group('sync log', () {
    test('survives a restart, because it outlives the bills it describes',
        () async {
      final sync = SyncRepositoryImpl(
        store,
        RemoteCatalogueSource(isOffline: () => false),
        SimulatedOrderTransport(isOffline: () => false),
      );

      final milk = (await products.findByBarcode('8901234500011'))!;
      await checkout(
        cart: Cart(lines: [CartLine(product: milk, quantity: 1)]),
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 62, tendered: 62),
        ],
        cashierName: 'Divya',
      );
      await sync.syncOrders();

      expect(sync.events, isNotEmpty);
      final summary = sync.events.first.summary;

      // The cache is dropped and rebuilt from disk, as it is on a cold start.
      await store.hydrate();

      expect(sync.events, isNotEmpty,
          reason: 'the only record that those bills went up must persist',);
      expect(sync.events.first.summary, summary);
      expect(sync.events.first.payload['invoices'], isNotEmpty);
    });

    test('a failed import is recorded with its error', () async {
      final sync = SyncRepositoryImpl(
        store,
        RemoteCatalogueSource(isOffline: () => true),
        SimulatedOrderTransport(isOffline: () => true),
      );

      await sync.importCatalogue();
      await store.hydrate();

      expect(sync.events.first.status, SyncStatus.failed);
      expect(sync.events.first.error, isNotNull);
    });
  });

  group('shift report scoping', () {
    Future<void> sell(String cashier, double qty) async {
      final milk = (await products.findByBarcode('8901234500011'))!;
      final due = Cart(lines: [CartLine(product: milk, quantity: qty)]).grandTotal;
      await checkout(
        cart: Cart(lines: [CartLine(product: milk, quantity: qty)]),
        payments: [
          PaymentSplit(method: PaymentMethod.cash, amount: due, tendered: due),
        ],
        cashierName: cashier,
      );
    }

    test('a cashier settles their own till, not the terminal', () async {
      final sync = SyncRepositoryImpl(
        store,
        RemoteCatalogueSource(isOffline: () => false),
        SimulatedOrderTransport(isOffline: () => false),
      );

      await sell('Divya', 2); // 124
      await sell('Rahul', 3); // 186

      final divya = await sync.todayReport(
        terminalId: 'TERM-01',
        cashierName: 'Divya',
        scopeToCashier: true,
      );
      final terminal = await sync.todayReport(
        terminalId: 'TERM-01',
        cashierName: 'Divya',
      );

      expect(divya.billCount, 1);
      expect(divya.grossSales, 124);
      expect(terminal.billCount, 2);
      expect(terminal.grossSales, 310);
    });

    test('scoping holds after the bills are uploaded and deleted', () async {
      final sync = SyncRepositoryImpl(
        store,
        RemoteCatalogueSource(isOffline: () => false),
        SimulatedOrderTransport(isOffline: () => false),
      );

      await sell('Divya', 2);
      await sell('Rahul', 3);
      await sync.syncOrders();
      expect(await sync.unsyncedCount(), 0);

      final divya = await sync.todayReport(
        terminalId: 'TERM-01',
        cashierName: 'Divya',
        scopeToCashier: true,
      );
      final terminal = await sync.todayReport(
        terminalId: 'TERM-01',
        cashierName: 'Divya',
      );

      expect(divya.grossSales, 124,
          reason: 'the archive must keep each cashier separable',);
      expect(divya.billCount, 1);
      expect(terminal.grossSales, 310);
      expect(terminal.billCount, 2);
    });
  });

  group('customer lookup', () {
    test('a mobile number matches however the cashier punctuates it', () async {
      await customers.create(const Customer(
        id: 'ignored',
        name: 'Punctuation Test',
        mobile: '9000000042',
      ),);

      for (final query in ['9000000042', '90000 00042', '90-000-00042']) {
        expect(
          (await customers.search(query)).map((c) => c.name),
          contains('Punctuation Test'),
          reason: 'searching "$query" should find the customer',
        );
      }
    });
  });

  group('tax invoice', () {
    test('the slab breakdown sums to the GST charged', () async {
      // Two different slabs plus a bill discount, so apportioning is in play.
      final milk = (await products.findByBarcode('8901234500011'))!; // 5%
      final all = await products.getAll();
      final eighteen = all.firstWhere((p) => p.gstRate == 0.18);

      final cart = Cart(
        lines: [
          CartLine(product: milk, quantity: 3),
          CartLine(product: eighteen, quantity: 7),
        ],
        billDiscount: const Discount(type: DiscountType.percentage, value: 13),
      );

      final summed = cart.taxBreakdown.values.fold(0.0, (a, b) => a + b);
      expect(summed, closeTo(cart.taxAmount, 0.0001));
    });
  });
}