💬 Loopin Backend

A secure, scalable Spring Boot backend for a modern messaging platform with subscription-based channels. Built for high-performance real-time communication with integrated payment processing.

🚀 Quick Start

Prerequisites

• Java 21+
• Docker & Docker Compose
• PostgreSQL 15+
• Redis 7+

Setup Instructions

# Clone the repository
git clone https://github.com/your-org/loopin-backend.git
cd loopin-backend

# Start dependencies with Docker Compose
docker-compose up -d postgres redis

# Configure environment variables
cp .env.example .env
# Edit .env with your configuration

# Run the application
./gradlew bootRun

Environment Variables

# Database Configuration
DATABASE_URL=jdbc:postgresql://localhost:5432/loopchat
DATABASE_USERNAME=loopchat
DATABASE_PASSWORD=your_password

# Redis Configuration
REDIS_HOST=localhost
REDIS_PORT=6379
REDIS_PASSWORD=

# JWT Configuration
JWT_SECRET=your_jwt_secret_key
JWT_EXPIRATION=86400000

# Razorpay Configuration
RAZORPAY_KEY_ID=your_razorpay_key_id
RAZORPAY_KEY_SECRET=your_razorpay_key_secret
RAZORPAY_WEBHOOK_SECRET=your_webhook_secret

# AWS S3 Configuration (Optional)
AWS_ACCESS_KEY_ID=your_access_key
AWS_SECRET_ACCESS_KEY=your_secret_key
AWS_S3_BUCKET=your_bucket_name
AWS_REGION=us-east-1

🎯 Key Features

🔐 Secure Authentication

• JWT-based authentication with automatic refresh
• Single-device login enforcement
• Device fingerprinting for enhanced security
• Secure password reset flow

💬 Real-Time Messaging

• WebSocket-based instant messaging
• Message delivery confirmations
• Typing indicators and read receipts
• Offline message queuing

📺 Subscription Channels

• Create paid and free channels
• Razorpay integration for payments
• Creator payout system
• Subscriber management

📁 Media Handling

• Secure file uploads to S3/MinIO
• Image compression and optimization
• CDN integration for fast delivery
• Multiple file format support

📊 Analytics & Monitoring

• Real-time system metrics
• Business analytics dashboard
• Payment transaction tracking
• User engagement insights

🏗️ Architecture

Technology Stack

• Backend: Spring Boot 3.x with WebFlux (Reactive)
• Database: PostgreSQL with Redis caching
• Authentication: JWT with RS256 signing
• Payments: Razorpay integration
• Storage: AWS S3 or MinIO
• Real-time: WebSocket/STOMP protocol

Project Structure

src/main/java/com/loopchat/
├── auth/           # Authentication & user management
├── messaging/      # Real-time messaging system
├── channels/       # Channel management & subscriptions
├── payments/       # Razorpay payment processing
├── media/          # File upload & storage
├── config/         # Spring configurations
├── security/       # Security configurations
└── common/         # Shared utilities & DTOs

📖 Documentation

Document	Description
🔧 GitHub Copilot Instructions	Complete guide for AI-assisted development
📋 Feature Documentation	Detailed feature specifications
🏗️ Architecture Guide	System architecture and design patterns
🔌 API Documentation	RESTful API endpoints and WebSocket events
🛡️ Security Guidelines	Security best practices and implementation
🚀 Deployment Guide	Production deployment instructions

🔌 API Overview

Authentication Endpoints

POST /api/v1/auth/register      # User registration
POST /api/v1/auth/login         # User login
POST /api/v1/auth/refresh       # Token refresh
POST /api/v1/auth/logout        # User logout

Messaging Endpoints

GET  /api/v1/conversations               # List conversations
POST /api/v1/conversations/{id}/messages # Send message
WS   /ws/chat                           # WebSocket connection

Channel Endpoints

GET  /api/v1/channels                # List all channels
POST /api/v1/channels                # Create new channel
POST /api/v1/channels/{id}/subscribe # Subscribe to channel

Payment Endpoints

POST /api/v1/payments/orders    # Create payment order
POST /api/v1/payments/verify    # Verify payment
POST /api/v1/payments/webhooks  # Razorpay webhooks

🧪 Testing

Run Tests

# Unit tests
./gradlew test

# Integration tests
./gradlew integrationTest

# Test coverage report
./gradlew jacocoTestReport

Test Configuration

• Unit Tests: JUnit 5 + Mockito
• Integration Tests: TestContainers for database
• WebSocket Tests: Spring WebSocket Test
• Coverage: JaCoCo with 80% minimum coverage

🚀 Deployment

Docker Deployment

# Build Docker image
docker build -t loopchat-backend .

# Run with Docker Compose
docker-compose up -d

Production Checklist

• Environment variables configured
• Database migrations applied
• SSL certificates installed
• Monitoring tools configured
• Backup strategy implemented
• Rate limiting configured

🔧 Development

Prerequisites for Contributors

• Java 21+ (OpenJDK recommended)
• IntelliJ IDEA or VS Code
• Docker for local dependencies
• Postman for API testing

Development Workflow

1. Setup: Follow quick start instructions
2. Branch: Create feature branch from main
3. Code: Follow architectural guidelines
4. Test: Write comprehensive tests
5. Review: Submit pull request for review
6. Deploy: Merge to main triggers deployment

Code Style

• Follow Spring Boot conventions
• Use meaningful variable names
• Document public APIs with JavaDoc
• Implement proper error handling
• Add comprehensive logging

📊 Monitoring

Health Endpoints

GET /actuator/health     # Application health
GET /actuator/metrics    # Application metrics
GET /actuator/info       # Application info

Key Metrics

• Performance: API response times, throughput
• Business: Messages sent, payments processed, active users
• System: JVM metrics, database connections, cache hit rates
• Security: Failed logins, rate limit hits, suspicious activities

🤝 Contributing

We welcome contributions! Please read our Contributing Guidelines for details on:

• Code of conduct
• Development process
• Pull request process
• Coding standards

Getting Started with Contributions

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🆘 Support

Documentation

• GitHub Copilot Instructions - AI development assistance
• Architecture Guide - System design patterns
• API Documentation - Complete API reference

Getting Help

• 🐛 Bug Reports: Use GitHub Issues
• 💡 Feature Requests: Use GitHub Discussions
• 📧 Security Issues: Email security@loopchat.com
• 💬 General Questions: Join our Discord community

Status

• ✅ MVP Features: Authentication, Messaging, Payments
• 🔄 In Development: Group chat, Voice messages
• 📋 Planned: E2E encryption, Analytics dashboard

---

Built with ❤️ for secure, scalable messaging by Gajanan Rathod