prantascode/ecommerce-website

1. This repository is a Spring Boot backend for an e-commerce system, not a full frontend app. The architectural center is a REST API that exposes business capabilities for authentication, catalog management, cart, orders, payments, reviews, wishlists, and admin/customer operations.

2. The codebase follows a clear layered structure: Controller handles HTTP endpoints, Service contains business rules, Repository provides persistence access, and Entity defines the database model. This is the main boundary an architecture diagram should show, with requests flowing downward and DTOs used at the API edge.

3. Authentication and authorization are a major subsystem. AuthController, AuthService, CustomUserDetailsService, JwtFilter, Jwtutil, and SecurityConfig work together to handle registration, login, JWT issuance/validation, refresh tokens, and role-based access control for ADMIN and CUSTOMER.

4. Domain data is modeled with JPA entities for User, Customer, Product, Brand, Category, Cart, CartItem, Order, OrderItem, Payment, Review, Wishlist, Discount, and RefreshToken. These entities are persisted through Spring Data repositories and represent the core business state in MySQL.

5. Product and catalog management are isolated into their own flow: ProductController and ProductService manage products, while BrandController/BrandService and CategoryController/CategoryService support classification and filtering. DiscountController/DiscountService adds pricing logic that likely affects product and order calculations.

6. Cart and checkout form another business pipeline. CartController and CartService manage cart state and cart items, then OrderController and OrderService convert cart contents into orders and order items. This is the key transactional handoff from shopping to purchase.

7. Payment integration is a separate boundary around external processing. PaymentController, PaymentService, and SSLCommerzConfig indicate integration with the SSLCommerz gateway for payment initiation and verification, with Payment persisted as an internal record of the transaction outcome.

8. Reviews and wishlists are auxiliary customer-facing features. ReviewController/ReviewService manage product feedback, and WishlistController/WishlistService handle saved items. These are independent from the core checkout path but still tied to authenticated users and products.

9. The API surface is strongly typed with request/response DTOs under Dto/Request and Dto/Response. This keeps controllers decoupled from persistence entities and makes the external contract explicit for login, registration, product updates, order placement, payment responses, and similar operations.

10. Error handling is centralized. Custom exceptions such as ResourceNotFoundException, DuplicateResourceException, InvalidRequestException, and UnauthorizedAccessException are translated by GlobalExceptionHandler into a structured ErrorResponseDto, which is an important cross-cutting boundary for API reliability.

11. The application includes operational support components: OpenApiConfig for Swagger/OpenAPI documentation, DataInitializer for bootstrapping data, and CartCleanupScheduler for periodic cart maintenance. These are supporting subsystems rather than primary business flows, but they affect runtime behavior.

12. Persistence and runtime environment are straightforward: the project uses Maven, Spring Boot, Spring Security, Spring Data JPA/Hibernate, and MySQL, with configuration driven from application.properties. There is a single backend deployable (EcommerceApplication) and a basic test entry point under src/test.