This is the backend for the ChatApp open source project. It provides real-time messaging, authentication, user management, and file/image upload support for the frontend. Built with Node.js, Express, MongoDB, and Socket.IO.

• User Authentication: Sign up, login, JWT-based authentication, and profile management.
• Real-Time Messaging: Instant messaging using Socket.IO.
• User Presence: Online/offline status updates.
• File & Image Uploads: Upload and share images via Cloudinary.
• RESTful API: For user and message management.
• MongoDB Database: Stores users and messages.
• Secure: Passwords hashed with bcrypt, JWT for authentication.
• CORS Support: For frontend-backend communication.

• Node.js & Express: Server and REST API
• MongoDB & Mongoose: Database and ODM
• Socket.IO: Real-time communication
• Cloudinary: Image/file uploads
• JWT: Authentication
• bcryptjs: Password hashing
• dotenv: Environment variable management
• CORS: Cross-origin resource sharing

• Node.js (v18+ recommended)
• MongoDB instance (local or cloud)
• Cloudinary account (for image uploads)

1. Clone the repository:

   git clone https://github.com/YOUR_GITHUB_REPO.git
   cd ChatApp/backend

2. Install dependencies:

   npm install

3. Environment Variables:

   Create a .env file in the backend directory with the following:

   MONGODB_URI=your_mongodb_connection_string
   JWT_SECRET=your_jwt_secret
   CLOUDINARY_CLOUD_NAME=your_cloudinary_cloud_name
   CLOUDINARY_API_KEY=your_cloudinary_api_key
   CLOUDINARY_API_SECRET=your_cloudinary_api_secret
   

4. Run the server:

   npm run dev

   The server will start on http://localhost:8080 by default.

• POST /api/v1/auth/signup — Register a new user
• POST /api/v1/auth/login — Login and receive JWT
• GET /api/v1/auth/check — Check authentication (protected)
• PUT /api/v1/auth/profile — Update user profile (protected)

• GET /api/v1/messages/ — Get users for sidebar (protected)
• GET /api/v1/messages/:userId — Get messages with a user (protected)
• POST /api/v1/messages/:receiverId — Send a message (protected)

• GET /api/status — Health check

• Connect: Client connects with userId in handshake query.
• getOnlineUsers: Receive list of online users.
• newMessage: Receive new messages in real time.

backend/
  controllers/      # Route handlers for users and messages
  lib/              # Database, Cloudinary, and utility functions
  middleware/       # Auth middleware
  models/           # Mongoose schemas (User, Message)
  routes/           # Express route definitions
  server.js         # Main server entry point

Contributions are welcome! Please open issues or pull requests for new features, bug fixes, or improvements.

ISC