import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../core/config/sync_config.dart';
import '../core/services/connectivity_service.dart';
import '../core/services/receipt_service.dart';
import '../core/services/sound_service.dart';
import '../data/datasources/local_store.dart';
import '../data/repositories/customer_repository_impl.dart';
import '../data/repositories/product_repository_impl.dart';
import '../data/datasources/remote_catalogue_source.dart';
import '../data/remote/http_order_transport.dart';
import '../data/remote/mqtt_order_transport.dart';
import '../data/remote/order_transport.dart';
import '../data/remote/simulated_order_transport.dart';
import '../data/repositories/store_repository_impl.dart';
import '../data/repositories/sync_repository_impl.dart';
import '../data/repositories/transaction_repository_impl.dart';
import '../data/local/terminal_identity.dart';
import '../data/sync/sync_engine.dart';
import '../domain/repositories/customer_repository.dart';
import '../domain/repositories/product_repository.dart';
import '../domain/repositories/sync_repository.dart';
import '../domain/repositories/transaction_repository.dart';
import '../domain/entities/store_account.dart';
import '../domain/usecases/checkout_sale.dart';
import '../presentation/auth/providers/auth_controller.dart';

/// Root data source. Overridden in tests with an in-memory double.
final localStoreProvider = Provider<LocalStore>((ref) => LocalStore.instance);

// ---------------------------------------------------------- Repositories
final productRepositoryProvider = Provider<ProductRepository>(
  (ref) => ProductRepositoryImpl(ref.watch(localStoreProvider)),
);

final customerRepositoryProvider = Provider<CustomerRepository>(
  (ref) => CustomerRepositoryImpl(ref.watch(localStoreProvider)),
);

final transactionRepositoryProvider = Provider<TransactionRepository>(
  (ref) => TransactionRepositoryImpl(ref.watch(localStoreProvider)),
);

/// Mirrors the Settings "Simulate offline" switch so the header can show it.
///
/// Without this the terminal claims LIVE while every call is being failed on
/// purpose, which reads as a real network fault.
final simulateOfflineProvider = StateProvider<bool>((ref) => false);

/// Simulated back-office endpoints. Held as singletons so the offline toggle
/// in Settings affects every call.
final remoteCatalogueProvider = Provider<RemoteCatalogueSource>(
  (ref) => RemoteCatalogueSource(
    isOffline: () => ref.read(simulateOfflineProvider),
  ),
);

// ------------------------------------------------------------------- Sync
/// How this terminal reaches the back office.
///
/// Defaults to the simulated route so a fresh install is usable with no broker
/// and no endpoint; Settings re-points it.
///
/// Store and terminal ids always come from this device's own identity, never
/// from a literal — two terminals publishing on the same topic is the failure
/// this exists to prevent.
final syncConfigProvider = StateProvider<SyncConfig>((ref) {
  final terminal = ref.watch(terminalIdentityProvider);
  return SyncConfig(
    storeId: terminal.storeId,
    terminalId: terminal.code,
  );
});

/// Real network state, folded with the Settings offline switch.
final connectivityServiceProvider = Provider<ConnectivityService>((ref) {
  final service = ConnectivityService(
    isSimulatedOffline: () => ref.read(simulateOfflineProvider),
  );
  ref.onDispose(service.dispose);
  return service;
});

/// The wire itself. Rebuilt when the configuration changes, and the old one is
/// closed so a re-pointed terminal does not keep a stale broker session open.
final orderTransportProvider = Provider<OrderTransport>((ref) {
  final config = ref.watch(syncConfigProvider);

  final transport = switch (config.transport) {
    TransportKind.mqtt => MqttOrderTransport(config: config),
    TransportKind.http => HttpOrderTransport(config: config),
    TransportKind.simulated => SimulatedOrderTransport(
        isOffline: () => ref.read(simulateOfflineProvider),
      ),
  };

  ref.onDispose(transport.dispose);
  return transport;
});

final syncRepositoryProvider = Provider<SyncRepository>(
  (ref) => SyncRepositoryImpl(
    ref.watch(localStoreProvider),
    ref.watch(remoteCatalogueProvider),
    ref.watch(orderTransportProvider),
    batchSize: ref.watch(syncConfigProvider).batchSize,
  ),
);

/// Decides when bills are uploaded. Started once, by the app shell.
final syncEngineProvider = Provider<SyncEngine>((ref) {
  final transport = ref.watch(orderTransportProvider);

  final engine = SyncEngine(
    repository: ref.watch(syncRepositoryProvider),
    connectivity: ref.watch(connectivityServiceProvider).onlineChanges,
    downlink: transport.downlink,
    onCatalogueChanged: () async {
      await ref.read(syncRepositoryProvider).importCatalogue();
      ref.invalidate(localStoreProvider);
    },
  );

  ref.onDispose(engine.dispose);
  return engine;
});

/// Live engine state for the header pill and the events screen.
final syncEngineStateProvider = StreamProvider<SyncEngineState>((ref) {
  final engine = ref.watch(syncEngineProvider);
  return engine.states.map((s) => s);
});

/// Store details and staff, read from this terminal's database.
final storeRepositoryProvider = Provider<StoreRepositoryImpl>(
  (ref) => StoreRepositoryImpl(ref.watch(localStoreProvider)),
);

/// The outlet, refreshed whenever staff or details change.
final storeAccountProvider = FutureProvider<StoreAccount>(
  (ref) => ref.watch(storeRepositoryProvider).load(
        email: DemoCredentials.email,
      ),
);

// ------------------------------------------------------------- Use cases
final checkoutSaleProvider = Provider<CheckoutSale>(
  (ref) => CheckoutSale(
    productRepository: ref.watch(productRepositoryProvider),
    customerRepository: ref.watch(customerRepositoryProvider),
    transactionRepository: ref.watch(transactionRepositoryProvider),
  ),
);

// -------------------------------------------------------------- Services
final soundServiceProvider =
    Provider<SoundService>((ref) => SoundService.instance);

final receiptServiceProvider =
    Provider<ReceiptService>((ref) => ReceiptService.instance);

// --------------------------------------------------------------- Session
class CashierSession {
  const CashierSession({
    required this.name,
    required this.role,
    required this.terminalId,
  });

  final String name;
  final String role;
  final String terminalId;
}

/// Identity of the physical till, read from its own database.
///
/// Falls back only before the store has opened; every real read happens after
/// `LocalStore.init`, which mints the identity if this device has never run
/// before.
final terminalIdentityProvider = Provider<TerminalIdentity>((ref) {
  final store = ref.watch(localStoreProvider);
  return store.isReady
      ? store.terminal
      : const TerminalIdentity(
          deviceId: 'unopened',
          code: 'T0000',
          name: 'Terminal',
          storeId: 'store-01',
        );
});

final cashierSessionProvider = StateProvider<CashierSession>((ref) {
  final terminal = ref.watch(terminalIdentityProvider);
  return CashierSession(
    name: 'Suriya',
    role: 'ADMIN',
    terminalId: terminal.code,
  );
});

/// Ticks once a minute to drive the header clock without rebuilding on every
/// frame.
final clockProvider = StreamProvider<DateTime>((ref) async* {
  yield DateTime.now();
  yield* Stream.periodic(const Duration(seconds: 20), (_) => DateTime.now());
});