💰 Crypto Wallet Application

A full-stack cryptocurrency wallet application built with Java 21 + Spring Boot backend and React + TypeScript frontend, featuring Bitcoin and USDT (TRC-20) wallet management.

🚀 Quick Start

Prerequisites

Before running the application, ensure you have the following installed:

• Java 21 or later
• Maven 3.6+
• Node.js 16+ and npm
• Git (optional, for cloning)

🎯 One-Command Startup

# Start both backend and frontend
./startwallet.sh

# Stop both services
./stopwallet.sh

📋 Manual Setup (Alternative)

If you prefer to run services manually:

Backend (Spring Boot)

cd backend
mvn spring-boot:run

Frontend (React)

cd frontend
npm install  # First time only
npm start

🌐 Application URLs

Once started, access the application at:

• 🖥️ Main Application: http://localhost:3000
• 🔧 Backend API: http://localhost:8080/api
• 🗄️ Database Console: http://localhost:8080/h2-console
  • JDBC URL: jdbc:h2:mem:testdb
  • Username: sa
  • Password: (leave empty)

📱 Features

🔐 Authentication

• User Registration: Create new accounts with secure password hashing
• Login System: Secure authentication with session management
• Auto-Login: Remember user sessions between visits

💼 Wallet Management

• Multi-Currency Support: Bitcoin (BTC) and USDT (TRC-20)
• Wallet Creation: Generate secure wallets with private keys
• Balance Tracking: Real-time balance updates
• Address Management: Secure address generation

💸 Transactions

• Send Crypto: Transfer Bitcoin and USDT to any address
• Transaction History: Complete transaction log with status tracking
• Fee Calculation: Automatic fee estimation
• Transaction Status: Pending, Confirmed, Failed states

📱 Mobile-Responsive Design

• Mobile-First: Optimized for all screen sizes
• Touch-Friendly: Large buttons and intuitive gestures
• Modern UI: Glass morphism design with smooth animations
• Responsive Navigation: Adaptive navigation for all devices

🛠️ Technology Stack

Backend

• Java 21 - Latest LTS version
• Spring Boot 3.2 - Application framework
• Spring Data JPA - Database abstraction
• Spring Security - Authentication & authorization
• H2 Database - In-memory database for development
• Lombok - Reduce boilerplate code
• Maven - Dependency management

Frontend

• React 18 - UI library
• TypeScript - Type safety
• Modern CSS - Custom responsive design
• Axios - HTTP client
• Local Storage - Session persistence

Crypto Libraries

• BitcoinJ - Bitcoin operations
• Web3j - Ethereum/Tron operations

📂 Project Structure

cryptowallet/
├── backend/                 # Spring Boot application
│   ├── src/main/java/
│   │   └── com/cryptowallet/
│   │       ├── controller/  # REST controllers
│   │       ├── service/     # Business logic
│   │       ├── repository/  # Data access
│   │       ├── entity/      # JPA entities
│   │       ├── dto/         # Data transfer objects
│   │       └── config/      # Configuration
│   ├── src/main/resources/
│   │   └── application.yml  # Application configuration
│   └── pom.xml             # Maven dependencies
├── frontend/                # React application
│   ├── src/
│   │   ├── components/      # React components
│   │   ├── services/        # API services
│   │   ├── types/           # TypeScript types
│   │   └── styles/          # CSS styles
│   ├── public/              # Static assets
│   └── package.json         # npm dependencies
├── logs/                    # Application logs
├── startwallet.sh          # Startup script
├── stopwallet.sh           # Stop script
└── README.md               # This file

🔧 Scripts Documentation

startwallet.sh

Comprehensive startup script that:

• ✅ Checks all prerequisites (Java, Maven, Node.js, npm)
• 🔄 Stops any existing instances on ports 3000 and 8080
• 🚀 Starts backend and frontend in correct order
• ⏱️ Waits for services to be ready before proceeding
• 📊 Shows real-time startup progress
• 📝 Creates detailed logs in logs/ directory
• 🎯 Provides all necessary URLs and information

stopwallet.sh

Clean shutdown script that:

• 🛑 Gracefully stops all services
• 🧹 Cleans up hanging processes
• ✅ Verifies all services are stopped
• 📋 Provides manual cleanup commands if needed

🔐 API Endpoints

Authentication

• POST /api/users/register - Register new user
• POST /api/users/login - User login

Users

• GET /api/users/{id} - Get user by ID
• GET /api/users/username/{username} - Get user by username
• PUT /api/users/{id} - Update user
• DELETE /api/users/{id} - Delete user

Wallets

• POST /api/wallets/user/{userId} - Create wallet
• GET /api/wallets/user/{userId} - Get user wallets
• GET /api/wallets/{walletId} - Get wallet by ID
• POST /api/wallets/{walletId}/refresh-balance - Refresh balance

Transactions

• POST /api/transactions/send - Send transaction
• GET /api/transactions/wallet/{walletId} - Get wallet transactions
• GET /api/transactions/user/{userId} - Get user transactions
• GET /api/transactions/hash/{txHash} - Get transaction by hash

🚀 Development

Running in Development Mode

1. Start Backend in Development Mode:

   cd backend
   mvn spring-boot:run -Dspring-boot.run.profiles=dev

2. Start Frontend in Development Mode:

   cd frontend
   npm start

Building for Production

1. Build Backend:

   cd backend
   mvn clean package
   java -jar target/crypto-wallet-backend-0.0.1-SNAPSHOT.jar

2. Build Frontend:

   cd frontend
   npm run build
   # Serve the build directory with a static server

🐛 Troubleshooting

Common Issues

1. Port Already in Use:

   # Kill processes on specific ports
   lsof -ti:8080 | xargs kill -9
   lsof -ti:3000 | xargs kill -9

2. Java Version Issues:

   # Check Java version
   java -version
   # Should be 21 or later

3. Maven Issues:

   # Clean and reinstall dependencies
   cd backend
   mvn clean install

4. Node.js Issues:

   # Clear npm cache and reinstall
   cd frontend
   rm -rf node_modules package-lock.json
   npm install

Log Files

Check the log files for detailed error information:

• Backend: logs/backend.log
• Frontend: logs/frontend.log

Real-time Log Monitoring

# Monitor backend logs
tail -f logs/backend.log

# Monitor frontend logs  
tail -f logs/frontend.log

🔒 Security Notes

• This is a development application with placeholder crypto implementations
• Do not use in production without implementing real blockchain integrations
• Private keys are stored in plain text for development purposes
• Always use HTTPS in production environments

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

📄 License

This project is licensed under the MIT License.

🆘 Support

If you encounter any issues:

1. Check the log files in the logs/ directory
2. Ensure all prerequisites are installed
3. Try running ./stopwallet.sh then ./startwallet.sh
4. Check if ports 3000 and 8080 are available

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Happy Trading! 🚀💰