💬 Chat App Backend

A real-time backend chat application built with Node.js, WebSocket (Socket.IO), JWT authentication, and MongoDB.

This is the backend for the real-time chat application:
chat-app-frontend

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🔧 Features

• ✅ JWT-based user authentication
• 🔌 Real-time communication with Socket.IO
• 🧠 MongoDB for storing users and messages
• ✨ Built with Javascript

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⚙️ Tech Stack

• Node.js
• Express.js
• MongoDB + Mongoose
• Socket.IO
• JWT

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📁 Project Structure

chat-app-backend/
├── src/
│   ├── config/        # DB and environment config
│   ├── controllers/   # RESTful logic
│   ├── models/        # Mongoose schemas
│   ├── routes/        # Express route handlers
│   ├── sockets/       # WebSocket events
│   └── index.ts       # Entry point
├── .env.example       # Sample environment variables
└── package.json

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🚀 Getting Started

1. Clone the project

git clone https://github.com/MatheusIshiyama/chat-app-backend.git
cd chat-app-backend

2. Install dependencies

npm install
# or
yarn

3. Create your .env

Copy .env.example to .env and configure:

PORT=4000
MONGO_URI=mongodb://localhost:27017/chatapp
JWT_SECRET=your_jwt_secret

4. Run the server

Development mode:

npm run dev

Production build:

npm run build
npm start

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📡 REST Endpoints

Method	Endpoint	Description
POST	/auth	Authenticate and return token
GET	/user	Get logged-in user data
POST	/user/register	Create a new user
GET	/user/confirm	Validate email from new user

Protected routes require: Authorization: Bearer <token>

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🔌 Socket.IO Events

Event Name	Direction	Description
sendFriendRequest	Client → Server	Send a friend request to a user by username
declineFriendRequest	Client → Server	Decline a received friend request
acceptFriend	Client → Server	Accept a received friend request
chat	Client → Server	Request to open or create a chat with a user by username
newMessage	Client → Server	Send a new message in an existing chat
chatId	Server → Client	Response with chat ID and friend name when chat is triggered
chatMessages	Server → Client	Regularly emits full message list of the current chat
chatLastMessages	Server → Client	Periodically sends a summary of last messages from all chats
friendsRequests	Server → Client	Periodically sends list of friend requests
friendList	Server → Client	Periodically sends current list of friends
alert	Server → Client	Emits alert messages like "user not found" or "error to add yourself"

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📄 License

Licensed under the MIT License.