Trading System Simulator

Introduction

The Trading System simulator is a simple platform designed to allow users to create an account and then send and receive virtual currency.

Technologies

• Tech Stack:
  • Frontend: React.js
  • Backend: Express.js
  • Database: PostgreSQL (Chosen for ACID-compliant transactions)
  • SQL Query Builder: Knex.js
  • Testing: Jest
• Containerization: Docker
• Folder Structure: The structure is modular, separating concerns and making the codebase easier to navigate.

Getting Started

Prerequisites

• Node.js v18
• Docker & Docker Compose
• A .env file in the root directory with the necessary environment variables (see env.example)
• Brew* (only for local development)
• Postgresql 14* (only for local development)

Development Using Docker (Recommended)

1. Make sure .env is copied over/configured from .env.example
2. Clone the repository: git clone https://github.com/your-repo-link/trading-system-sim.git
3. Navigate to the project directory: cd trading-system-sim
4. If you ran local development first a. Change into Server directory: cd server b. Remove node_modules: rm -rf node_modules c. Remove package-lock.json: rm -rf package-lock.json d. Switch back to root: cd ..
5. Build the Docker services: docker-compose build
6. Start the Docker services: docker-compose up
7. Once the services are up, the backend should be accessible at http://localhost:3001 and the frontend at http://localhost:3000.

Testing

Tests are written using Jest. To run tests, use the command: docker exec -it trading-system-sim-server-1 npm test.

Local Development (Without Docker)

System

1. Start Postgresql 14 brew services start postgresql or run manually (/usr/local/opt/postgresql@14/bin/postgres -D /usr/local/var/postgres)
2. Make sure to set USING_DOCKER flag in .env to false

Server

1. Create development and testing database with npm run create-db
2. cd server
3. npm run knex:migrate:latest
4. npm i
5. npm start

Client

1. cd client
2. npm i
3. npm start

Testing

Tests are written using Jest. To run tests, use the command: npm run test.

Database Schema

The system uses two tables:

1. Users: Stores user details.

• id: Unique identifier.
• username: User's chosen name.
• password_hash: Hashed password for security.
• balance: Current balance of token.

2. Transactions: Logs all transactions.

• id: Unique identifier.
• sender_id: Reference to the user sending token.
• receiver_id: Reference to the user receiving token.
• amount: Amount of token being transferred.
• timestamp: When the transaction occurred.

Frontend Guide

The frontend is built using React.js and styled with TailwindCSS. The main pages/components include:

• Login Page: Allows users to log in.
• Registration Page: Allows new users to register.
• User Page: Displays user's balance and allow users to send funds if logged in.

API Reference

Auth

POST /auth/login

Description: Authenticate a user and return a JWT token.

Request Body:

{
  "username": "string",
  "password": "string"
}

Sample 200 Response:

{
  "token": "your-jwt-token"
}

Users

POST /users

Description: Register a new user.

Request Body:

{
  "username": "string",
  "password": "string"
}

Sample 201 Response:

{
  "token": "your-jwt-token"
}

GET /users/:id

Description: Retrieve details of a user.

Parameters:

• id: The ID of the user.

Sample 200 Response:

{
  "id": 1,
  "username": "sampleUser",
  "balance": 1000
}

Transactions

POST /transactions

Description: Create a new transaction. Authentication: Set the bearer token in the Authorization header. You can obtain this token by logging in.

Request Body:

{
  "senderId": 1,
  "receiverId": 2,
  "amount": 100
}

Sample 201 Response:

{
  "transactionId": 1,
  "senderId": 1,
  "receiverId": 2,
  "amount": 100
}

Error Handling

In case of an error, the API will return a response in the following format:

{
  "message": "Error message here",
  "error": "Detailed error information (if available)"
}