CoreChain-Notification

Notification service for CoreChain HRM system using Firebase Cloud Messaging (FCM) and Kafka.

📋 Overview

This is a Golang-based notification service that:

• Consumes Kafka messages from the NestJS backend
• Sends push notifications via Firebase Cloud Messaging (FCM)
• Stores notification history in PostgreSQL
• Supports multiple notification types (tasks, messages, calls)

Current Flow: Task created on server (NestJS) → Kafka → Notification service (Golang) → FCM → Mobile app

🏗️ Architecture

Built with Clean Architecture principles:

• cmd/server/ - Application entry point
• internal/domain/ - Business entities and interfaces
• internal/application/ - Business logic (services & DTOs)
• internal/infrastructure/ - External integrations (Kafka, FCM, PostgreSQL)
• internal/delivery/ - Message handlers
• pkg/ - Public/shared code

🚀 Quick Start

Prerequisites

• Go 1.21+
• Docker & Docker Compose
• PostgreSQL 15
• Kafka (or use Docker Compose setup)

Setup

1. Clone and setup

   cd CoreChain-Notification
   cp .env.example .env
   # Edit .env with your configuration

2. Install dependencies

   make deps

3. Start with Docker Compose (includes PostgreSQL, Kafka, and service)

   make docker-up

4. Or run locally

   # Make sure PostgreSQL and Kafka are running
   make run

📝 Configuration

Configure via environment variables (see .env.example):

# Database
DB_HOST=localhost
DB_PORT=5432
DB_USER=notification_user
DB_PASSWORD=notification_pass
DB_NAME=notification_db

# Kafka
KAFKA_BROKERS=localhost:9092
KAFKA_GROUP_ID=notification-service-group
KAFKA_TOPIC_TASK_CREATED=task.created

# FCM
FCM_CREDENTIALS_PATH=./google-services.json
FCM_PROJECT_ID=corechain-e1321

🔧 Available Commands

make help           # Show all available commands
make deps           # Download dependencies
make build          # Build the application
make run            # Run locally
make test           # Run tests
make docker-up      # Start with Docker Compose
make docker-down    # Stop Docker services
make docker-logs    # View logs

📦 Project Structure

CoreChain-Notification/
├── cmd/server/              # Main application
├── internal/
│   ├── config/             # Configuration management
│   ├── domain/             # Domain models & interfaces
│   ├── application/        # Services & DTOs
│   ├── infrastructure/     # Kafka, FCM, PostgreSQL
│   ├── delivery/           # Message handlers
│   └── utils/              # Logger, errors, validators
├── deployments/
│   └── docker/             # Dockerfile & docker-compose
└── configs/                # Config files

🔔 Supported Notifications

✅ Implemented

• Task Created - Notifies when a new task is assigned

🚧 Planned

• Task Updated - Notifies when a task is modified
• New Message - Notifies on incoming messages
• Incoming Call - Notifies on incoming calls

🛠️ Development

Adding New Notification Type

1. Add constant in pkg/constants/notification_types.go
2. Create DTO in internal/application/dto/
3. Add template in internal/infrastructure/fcm/templates.go
4. Create handler in internal/delivery/kafka/
5. Register handler in cmd/server/main.go

Testing

# Run all tests
make test

# Run with coverage
make test-coverage

🐳 Docker

Build Image

make docker-build

Docker Compose Services

• postgres - PostgreSQL database (port 5432)
• kafka - Apache Kafka (port 9092)
• zookeeper - Kafka dependency (port 2181)
• notification-service - This service (port 8080)

📊 Database Schema

Notifications Table

Stores all notification records with delivery status tracking.

User FCM Tokens Table

Tracks device tokens for each user.

See deployments/docker/migrations/001_init.sql for full schema.

🤝 Integration with NestJS

The NestJS backend should publish messages to Kafka in this format:

{
  "event_type": "task.created",
  "timestamp": "2025-12-26T07:29:50Z",
  "data": {
    "_id": "task-id",
    "title": "Task title",
    "assignedTo": "user-id",
    ...
  },
  "metadata": {
    "assignedToUser": {
      "_id": "user-id",
      "fcmToken": "device-token",
      "name": "User Name"
    }
  }
}

📄 License

MIT License