FinTech API

Project Description

The FinTech API is a robust and secure backend solution designed for financial technology applications. It provides a comprehensive set of features for user management, account handling, and transaction processing. Built with NestJS and leveraging modern web technologies, this API ensures high performance, scalability, and maintainability.

Tech Stack

Framework: NestJS
Language: TypeScript
Database: PostgreSQL
ORM: Prisma
Authentication: Passport.js, JWT
Validation: Class Validator
API Documentation: Swagger
Testing: Jest
Containerization: Docker
CI/CD: GitHub Actions

Project Architecture

The project follows a modular architecture based on NestJS best practices:

Modules: Each feature (Users, Accounts, Transactions, Auth) is encapsulated in its own module, promoting separation of concerns and maintainability.
Controllers: Handle incoming HTTP requests and define API endpoints.
Services: Contain business logic and interact with repositories.
Repositories: Abstract database operations and interact directly with the Prisma ORM.
DTOs (Data Transfer Objects): Define the structure of data for requests and responses.
Guards: Implement authentication and authorization checks.
Interceptors: Handle cross-cutting concerns like serialization.
Decorators: Custom decorators for things like current user extraction.

Project Structure

src/
├── auth/
├── users/
│   └── contacts/
├── accounts/
├── transactions/
├── database/
├── core/
│   └── serialize/
├── utils/
└── main.ts

This structure allows for easy navigation, scalability, and maintenance of the codebase. Each module (auth, users, accounts, transactions) contains its own controllers, services, and DTOs, keeping related functionality together.

Features

1. User Management

User registration and authentication
Profile management (update details, change password, change email)
Contact information management

2. Account Management

Create and manage multiple accounts per user
View account details and balance
Close accounts

3. Transaction Processing

Deposit funds
Withdraw funds
Transfer funds between accounts
Transaction history and details

4. Security

JWT-based authentication
Role-based access control
Password hashing and validation

Sequence Diagrams

User Registration

sequenceDiagram
    participant Client
    participant AuthController
    participant UsersService
    participant Database

    Client->>AuthController: POST /auth/register
    AuthController->>UsersService: create(userData)
    UsersService->>Database: Insert user data
    Database-->>UsersService: Confirm insertion
    UsersService-->>AuthController: Return user object
    AuthController-->>Client: Return success message

User Login

sequenceDiagram
    participant Client
    participant AuthController
    participant AuthService
    participant UsersService
    participant JwtService

    Client->>AuthController: POST /auth/login
    AuthController->>AuthService: validateUser(credentials)
    AuthService->>UsersService: getOneBy(username/email)
    UsersService-->>AuthService: Return user
    AuthService->>AuthService: Validate password
    AuthService-->>AuthController: Return validated user
    AuthController->>AuthService: makeToken(userId)
    AuthService->>JwtService: sign(payload)
    JwtService-->>AuthService: Return JWT
    AuthService-->>AuthController: Return token
    AuthController-->>Client: Return access token

Create Account

sequenceDiagram
    participant Client
    participant AccountsController
    participant AccountsService
    participant Database

    Client->>AccountsController: POST /accounts
    AccountsController->>AccountsService: create(userId)
    AccountsService->>Database: Insert account data
    Database-->>AccountsService: Confirm insertion
    AccountsService-->>AccountsController: Return account object
    AccountsController-->>Client: Return created account

Deposit Transaction

sequenceDiagram
    participant Client
    participant TransactionsController
    participant AccountsService
    participant TransactionsService
    participant Database

    Client->>TransactionsController: POST /transactions/deposit
    TransactionsController->>AccountsService: getOneById(accountId)
    AccountsService-->>TransactionsController: Return account
    TransactionsController->>AccountsService: validate(user, account)
    TransactionsController->>TransactionsService: calcTax(amount)
    TransactionsController->>TransactionsService: createDeposit(accountId, netAmount)
    TransactionsService->>Database: Insert transaction & Update balance
    Database-->>TransactionsService: Confirm transaction
    TransactionsService-->>TransactionsController: Return transaction object
    TransactionsController-->>Client: Return transaction details

Getting Started

Prerequisites

Before you begin, ensure you have the following installed:

Node.js (v21.0.0 recommended)
Yarn package manager
Docker and docker-compose

Installation

Clone the repository:

git clone https://github.com/ahmdhusam/fintech.git
cd fintech

Install dependencies:
```
yarn install
```
Set up environment variables:
- Create a .env file in the project root
- Copy the contents from .env.example to .env
- Modify the values as needed for your local setup

Database Setup

Start the Docker containers:
```
docker-compose up -d
```
This will start the PostgreSQL database container.
Run database migrations:
```
yarn prisma migrate dev
```

Running the Application

Start the application in development mode:
```
yarn start:dev
```
The API will be available at http://localhost:3000 by default.
For production builds:
```
yarn build
yarn start:prod
```

Documentation

API documentation is available at /api/docs when the server is running, powered by Swagger.

Testing

The project includes unit tests and e2e tests. Run tests using:

yarn test
yarn test:e2e

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License.