feat: Implement comprehensive notification system with DDD architecture

[Scerutti]

🎯 Overview

Implementation of a complete notification microservice with email and Telegram support, following Domain-Driven Design (DDD) principles and Clean Architecture.

✨ Features Implemented

Core Functionality

• Multi-channel notifications (Email via Resend, Telegram Bot API)
• Asynchronous processing with BullMQ and Redis
• MongoDB persistence with Mongoose
• REST API with comprehensive Swagger documentation
• Health checks for all services

Architecture

• Domain-Driven Design with entities, value objects, and domain services
• Clean Architecture with clear separation of concerns
• Repository pattern for data access
• Use cases for business logic
• Dependency injection with proper abstractions

API Endpoints

• POST /notifications - Create and send notifications
• GET /notifications - List notifications with filters
• GET /notifications/stats - Get notification statistics
• GET /notifications/test-telegram - Test Telegram connection
• POST /notification-config - Configure notification channels
• GET /notification-config - Get configuration by email
• PUT /notification-config/:id - Update configuration
• GET /health - Health check endpoint

Technical Stack

• NestJS with Fastify
• MongoDB with Mongoose
• Redis with BullMQ
• Resend for email delivery
• Telegram Bot API for messaging
• Docker and Docker Compose
• Swagger for API documentation

🔧 Configuration

All sensitive data is managed through environment variables:

• MONGODB_URI
• REDIS_URL
• RESEND_API_KEY
• TELEGRAM_BOT_TOKEN
• TELEGRAM_CHAT_ID

🚀 Deployment

Ready for production deployment with Docker:

docker-compose up -d

📊 Status

• ✅ All core features implemented
• ✅ API documentation complete
• ✅ Health checks working
• ✅ Error handling implemented
• ✅ Logging and observability
• ✅ Production-ready configuration

🎉 Ready for Production

This implementation provides a robust, scalable notification system that can handle email and Telegram notifications asynchronously with proper error handling and monitoring.