second commit

lib/presentation/auth/providers/auth_controller.dart

@@ -0,0 +1,115 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../../core/constants/app_constants.dart';
+import '../../../domain/entities/store_account.dart';
+
+/// Sign-in state for the terminal.
+sealed class AuthState {
+  const AuthState();
+
+  bool get isAuthenticated => this is Authenticated;
+}
+
+class Unauthenticated extends AuthState {
+  const Unauthenticated();
+}
+
+class Authenticating extends AuthState {
+  const Authenticating();
+}
+
+class Authenticated extends AuthState {
+  const Authenticated({required this.store, required this.user});
+
+  final StoreAccount store;
+  final StaffUser user;
+}
+
+class AuthFailure extends AuthState {
+  const AuthFailure(this.message);
+
+  final String message;
+}
+
+/// Credentials that ship with the demo build.
+class DemoCredentials {
+  const DemoCredentials._();
+
+  static const String email = 'admin@nearle.in';
+  static const String password = 'nearle123';
+}
+
+const _demoStore = StoreAccount(
+  id: 'store-001',
+  name: AppConstants.storeName,
+  email: DemoCredentials.email,
+  address: AppConstants.storeAddress,
+  gstin: AppConstants.storeGstin,
+  phone: AppConstants.storePhone,
+  staff: [
+    StaffUser(id: 'u1', name: 'Suriya', role: StaffRole.admin, pin: '1234'),
+    StaffUser(id: 'u2', name: 'Divya', role: StaffRole.manager, pin: '2345'),
+    StaffUser(id: 'u3', name: 'Rahul', role: StaffRole.cashier, pin: '3456'),
+  ],
+);
+
+/// Validates store credentials and holds the signed-in session.
+///
+/// Backed by a hardcoded account for now; swapping in a real identity provider
+/// means changing only [signIn].
+class AuthController extends StateNotifier<AuthState> {
+  AuthController() : super(const Unauthenticated());
+
+  Future<bool> signIn({
+    required String email,
+    required String password,
+  }) async {
+    state = const Authenticating();
+
+    // Stand-in for the network round trip.
+    await Future<void>.delayed(const Duration(milliseconds: 600));
+
+    final normalised = email.trim().toLowerCase();
+
+    if (normalised != DemoCredentials.email) {
+      state = const AuthFailure('No store is registered against that email.');
+      return false;
+    }
+
+    if (password != DemoCredentials.password) {
+      state = const AuthFailure('Incorrect password. Please try again.');
+      return false;
+    }
+
+    state = Authenticated(store: _demoStore, user: _demoStore.staff.first);
+    return true;
+  }
+
+  /// Switches the active operator without signing the store out.
+  void switchUser(StaffUser user) {
+    final current = state;
+    if (current is! Authenticated) return;
+    state = Authenticated(store: current.store, user: user);
+  }
+
+  void signOut() => state = const Unauthenticated();
+
+  void clearError() {
+    if (state is AuthFailure) state = const Unauthenticated();
+  }
+}
+
+final authControllerProvider =
+    StateNotifierProvider<AuthController, AuthState>((ref) => AuthController());
+
+/// The signed-in store, or null before sign-in.
+final currentStoreProvider = Provider<StoreAccount?>((ref) {
+  final s = ref.watch(authControllerProvider);
+  return s is Authenticated ? s.store : null;
+});
+
+/// The active operator, or null before sign-in.
+final currentUserProvider = Provider<StaffUser?>((ref) {
+  final s = ref.watch(authControllerProvider);
+  return s is Authenticated ? s.user : null;
+});