FC-InnerCircle-ICD2 commerce-BE .cursorrules file for Java

### **1. Technology Stack**
- **Framework**: Java Spring Boot 3, Gradle, Java 21
- **Dependencies**:
    - Spring Web, Spring Data JPA, Lombok, MySQL driver
- **Databases**: MySQL
- **Caching/Task Queue**: Redis, EhCache, RabbitMQ, or Kafka (if needed)

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### **2. Application Logic Design**
- **Layer Separation**:
    - **Controller**: Handles requests and responses
    - **Service**: Business logic
    - **Repository(DAO)**: Database interaction
- **Separation of DTO and Entity**:
    - DTO: Data transfer between Controller ↔ Service
    - Entity: Directly interacts with the database
- RestController handles requests/responses and does not Autowire Repositories directly (Controller → Service → Repository flow).
- Avoid writing raw SQL unless optimizing performance.

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### **3. Entities**
- **Annotations**: Entity classes are annotated with `@Entity`.
- **Lombok**: Use `@Data`, `@Getter`, `@Setter` to minimize boilerplate code.
- **ID Configuration**:
    - `@Id` + `@GeneratedValue(generator = "uuid")`
    - `@GenericGenerator(name = "uuid", strategy = "uuid2")`
- **Lazy Loading**: Use `FetchType.LAZY` by default for relationships.
- **Validation**: Ensure data integrity using annotations like `@Valid`, `@NotNull`, `@Size`.

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### **4. Repository (DAO)**
- **Repository Interface**: Extend `JpaRepository`.
- **Query Writing**:
    - Use `@Query` for custom queries.
    - Follow naming conventions for Query Methods (e.g., `findBy`, `countBy`).
- **Entity Graph**:
    - Use `@EntityGraph(attributePaths={"..."})` to avoid N+1 problems.
- **DTO Mapping**: Map multi-join queries to DTOs.

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### **5. Service**
- **Class Structure**:
    - Implementation: `class SvcService`
- **Annotations**: Add `@Service` to indicate Spring management.
- **Dependency Injection**: Use `@RequiredArgsConstructor` with `private final` fields.
- **Transaction Management**:
    - Use `@Transactional` for database consistency.

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### **6. RestController**
- Configure base routes with `@RestController` and `@RequestMapping("/api/v1")`.
- Use HTTP method-specific mappings (e.g., `@GetMapping`, `@PostMapping`) for routing.
- Wrap all method logic in try-catch and manage exceptions with a GlobalExceptionHandler.

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### **7. Configuration and Properties**
- Separate profiles using `application-{profile}.yml` for dev, test, prod environments.
- Use `@ConfigurationProperties` for type-safe configuration.

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### **8. Testing**
- Use `@SpringBootTest` to load the application context.
- Use in-memory DB (e.g., H2) for testing Repository layers.

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### **9. Error Handling and Validation**
- Use `@ControllerAdvice` and `@ExceptionHandler` for global and method-level exception handling.
- Validate data integrity with Spring Validator (`@Valid`, `BindingResult`).
- Define custom exceptions tailored to business logic.

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### **10. Security**
- JWT-based token authentication.
- RBAC (Role-Based Access Control) or OAuth2 for authorization.
- Apply filters to protect against SQL Injection, XSS, CSRF.

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### **11. Performance and Scalability**
- Caching: Use Redis or EhCache to reduce database load.
- Asynchronous Tasks: Optimize response times with `@Async`.
- Database Optimization: Use JPQL and fetch join (`JOIN FETCH`).

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### **12. Build and Deployment**
- Manage dependencies and builds with Gradle.
- Containerize applications using Docker.
- Set up CI/CD pipelines with Jenkins or GitHub Actions.

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### **13. Best Practices**
- Role Separation: Controllers handle HTTP requests, Services manage business logic, and Repositories handle database interactions.
- Loose Coupling: Use dependency injection to improve testability and reusability.
- Task Scheduling: Use `@Scheduled` and `@Async` for scheduled and asynchronous tasks.
- Comprehensive Testing: Conduct regression, integration, and unit testing with JUnit and Spring Test.