The Emporion API is a transactional backend designed to handle various operations related to users, products, and orders.

The API is designed with the following principles in mind:

1. RESTful: The API follows the principles of Representational State Transfer (REST). It uses standard HTTP methods like GET, POST, PUT, DELETE to perform operations on the resources.

2. Resource-Oriented: Each entity like a user, product, or order is considered a resource and has a corresponding endpoint.

3. Stateless: Each request from the client to the server must contain all the information needed to understand and process the request.

4. Client-Server Architecture: The client and the server are separate entities that communicate over HTTP. This separation allows the client and server to be developed and deployed independently.

5. Layered System: The architecture is composed of multiple layers, each with specific responsibilities. This separation of concerns aids in maintainability and scalability.

Here are some of the main endpoints provided by the API:

• GET /users/{id}: Fetches the details of a user with the given ID.
• POST /register: Registers a new user.
• POST /login: Authenticates a user and returns a token.
• GET /products: Fetches a list of all products.
• POST /cart/checkout: Processes a user's cart and places an order.

sequenceDiagram
    participant U as User
    participant S as API Server
    participant P as Postgres DB

    U->>S: GET /users/{id}
    U->>S: POST /register
    U->>S: POST /login
    U->>S: GET /products
    U->>S: POST /cart/checkout
    S->>P: SELECT * FROM users WHERE id = $1

The API uses a Postgres database to store and retrieve data. The database schema is designed to efficiently support the API operations.

The API includes unit tests to ensure the correctness of the code. The tests are located in the service directory, with each service having its own test file.