Leitner System API

This project implements a Leitner System learning application backend using Node.js, Express, and Hexagonal Architecture.

Architecture

The project follows Hexagonal Architecture (Ports & Adapters) and Domain-Driven Design (DDD) principles.

• Domain (src/domain): Contains the core business logic (Entities, Value Objects, Ports). It has NO dependencies on outer layers.
• Application (src/application): Contains Use Cases that orchestrate the domain logic.
• Infrastructure (src/infrastructure): Contains adapters for external concerns (Web API, Persistence).

Prerequisites

• Node.js (v14+ recommended)
• npm

Installation

npm install

Running the Server

npm start

The server will start on http://localhost:8080.

Running Tests

To run all tests (Unit & Integration) with coverage:

npm test -- --coverage

API Endpoints

• GET /cards: Get all cards (optional tags query param).
• POST /cards: Create a new card.
• GET /cards/quizz: Get cards due for review (optional date query param).
• PATCH /cards/:cardId/answer: Submit an answer (isValid: boolean).

Design Choices

• Hexagonal Architecture: To decouple business logic from the framework and database.
• In-Memory Repository: Simulates a database for this exercise. Can be easily swapped with a real DB adapter.
• Value Objects: Category handles the Leitner interval logic.