new project stable version

lib/domain/usecase/change_pin_usecase.dart

@@ -0,0 +1,27 @@
+import 'package:be_happy/domain/repositories/pin_repository.dart';
+
+import '../repositories/auth_repository.dart';
+
+class ChangePinUseCase {
+  final PinRepository repository;
+
+  ChangePinUseCase(this.repository);
+
+  Future<void> call({
+    required String oldPin,
+    required String newPin,
+  }) async {
+    final savedPin = await repository.getSavedPin();
+
+    if (savedPin != oldPin) {
+      throw Exception('Wrong old PIN');
+    }
+
+    if (newPin.length != 6) {
+      throw Exception('Invalid new PIN');
+    }
+
+    await repository.savePin(newPin);
+  }
+}
+