1. Project Documentation

Project Name: Wallet App Backend

Overview

This backend powers a USDC wallet application with Google Sign-In authentication, wallet creation, sending and receiving funds, transaction history, and settings management including Panic Mode. It is built with TypeScript, Node.js, Express, and MongoDB.

The backend is designed for easy integration with a mobile or web frontend (e.g., React, Flutter), following RESTful principles and JSON responses.

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Features

• Google OAuth2 Sign-In – Verify Google ID token server-side, create user + wallet.
• JWT Authentication – Secure access to protected endpoints.
• Wallet Management – USDC balance tracking, receive address generation.
• Withdraw Flow – Preview transaction, confirm with PIN, panic mode enforcement.
• Receive Flow – QR code token, NFC simulation endpoints.
• Transactions – Record and fetch sent/received transactions.
• Settings – Edit name, toggle panic mode.
• Security – Bcrypt-hashed PIN, rate limiting, helmet for headers.

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Tech Stack

• Language: TypeScript
• Runtime: Node.js
• Framework: Express
• Database: MongoDB (via Mongoose)
• Auth: Google OAuth2, JWT
• Security: bcrypt, helmet, express-rate-limit

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Folder Structure

src/
├─ config/        # DB connection
├─ middleware/    # Auth + error handlers
├─ models/        # Mongoose schemas
├─ controllers/   # Business logic
├─ routes/        # Route definitions
├─ utils/         # Helper functions & validation
└─ server.ts      # Entry point

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Setup Instructions

1. Clone & Install

git clonehttps://github.com/useaura/Backend.git
cd Backend
npm install

2. Configure Environment Create a .env file:

PORT=4000
MONGO_URI=mongodb://localhost:27017/auraPay
JWT_SECRET=super_secret_jwt_key_here
JWT_EXPIRES_IN=7d
GOOGLE_CLIENT_ID=your_google_client_id.apps.googleusercontent.com
PIN_SALT_ROUNDS=10

3. Run in Dev Mode

npm run dev

4. Build & Start (Prod)

npm run build
npm start

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Development Notes

• Monetary Values – Stored as floats for demo; in production use integers for smallest USDC units.
• Blockchain – This backend simulates USDC transfers; production deployments should integrate with an actual blockchain or custody service.
• PIN – Only bcrypt hash stored; never store plaintext.
• Panic Mode – When active, all send/receive flows are blocked.

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