💬 CLI Chat Application

A real-time command-line chat application built with TypeScript, Node.js, and Firebase Realtime Database.

This project allows multiple users to communicate through a terminal using a shared group chat or private direct messages. It demonstrates real-time communication, user authentication, online presence tracking, and terminal-based interaction without relying on any graphical interface.

✨ Features

• 🔐 Simple User Authentication

  • Login using User ID and Password
  • Credentials stored in Firebase Realtime Database

• 🌐 Real-Time Group Chat

  • Multiple users can communicate simultaneously
  • Messages are delivered instantly using Firebase listeners

• 💬 Direct Messaging

  • One-to-one conversations between registered users
  • Dedicated conversation channel for every pair of users

• 🟢 Online / Offline Presence

  • Users automatically become online after login
  • Status changes back to offline when the application exits

• ⚡ Real-Time Synchronization

  • Uses Firebase Realtime Database
  • No polling or manual refresh required

• 💻 Terminal Based Interface

  • Lightweight CLI experience
  • Built using Node.js readline module

📦 Installation

Install Globally

npm install -g cli-chatapplication

or run it directly without installing

npx cli-chatapplication

Verify Installation

cli-chat

If installed correctly, you'll see:

CLI Chat Application

Enter User ID:
>

🚀 Usage

Start the application

cli-chat

Login

Enter your credentials

CLI Chat Application

Enter User ID:
> om-macbook

Enter Password:
> 123456

After successful authentication you'll see

Logged in as Om's MacBook

1. Group Chat
2. Direct Message

>

Group Chat

Select

1

Type your message

> Hello everyone!

Every connected user will instantly receive the message.

Direct Message

Select

2

Choose a user

Available Users

1. Om's iPad
2. Om's iPhone

Select User:
> 1

Now every message you type will be sent only to the selected user.

Exit

Press

Ctrl + C

The application automatically:

• Marks you offline
• Closes the connection
• Exits gracefully

🛠 Tech Stack

| Technology | Purpose | |------------|---------| | TypeScript | Programming Language | | Node.js | Runtime | | Firebase Realtime Database | Real-time backend | | Firebase SDK | Database Communication | | Readline | Terminal Input | | npm | Package Management |

📂 Project Structure

src/
│
├── firebase.ts
│   Firebase configuration and database operations
│
├── index.ts
│   Application entry point
│   Handles authentication and application flow
│
├── groupChat.ts
│   Group chat functionality
│
└── directChat.ts
    Direct messaging functionality

🔐 User Authentication

Users are stored inside Firebase Realtime Database.

Example

users
│
├── om-macbook
│     username
│     password
│     online
│
├── om-ipad
│     username
│     password
│     online
│
└── om-iphone
      username
      password
      online

When the application starts

CLI Chat Application

Enter User ID:
>

Enter Password:
>

If the credentials are valid

• User is marked online
• Chat session starts

If invalid

Invalid User ID or Password

🌍 Group Chat

Messages are stored under

groupMessages/

Each message contains

{
  "senderId": "om-macbook",
  "text": "Hello World",
  "timestamp": 1751972382
}

Messages are synchronized in real time across all connected terminals.

💬 Direct Messaging

Private conversations are stored separately.

Conversation IDs are generated by sorting user IDs alphabetically.

Example

messages/

om-ipad_om-macbook/

om-ipad_om-iphone/

om-macbook_om-iphone/

This ensures only one conversation exists between two users.

🟢 Presence System

Each user maintains an online status.

{
    "online": true
}

Status is updated

• On successful login
• When the application exits

🔥 Firebase Database Structure

users
│
├── userId
│     username
│     password
│     online
│
├── ...
│

groupMessages
│
├── messageId
│     senderId
│     text
│     timestamp
│
└── ...

messages
│
├── conversationId
│      messageId
│          senderId
│          receiverId
│          text
│          timestamp

🚀 How It Works

User Login
      │
      ▼
Firebase Authentication Check
      │
      ▼
Mark User Online
      │
      ▼
Select Chat Mode
      │
      ├───────────────┐
      ▼               ▼
 Group Chat      Direct Chat
      │               │
      ▼               ▼
Realtime Firebase Listeners
      │
      ▼
Instant Message Delivery

📸 Terminal Preview

CLI Chat Application

Enter User ID:
> om-macbook

Enter Password:
> ******

Logged in as Om's MacBook

1. Group Chat
2. Direct Message

> 1

--------------------------------

om-ipad:
Hello

om-macbook:
Hi!

>

🎯 Learning Outcomes

This project demonstrates

• Firebase Realtime Database
• Real-time communication
• CLI application development
• TypeScript
• Node.js
• Authentication flow
• Presence management
• Event-driven programming
• npm package development

🚧 Future Improvements

• End-to-end encryption
• Gemini AI integration
• File sharing
• Typing indicators
• Message reactions
• Chat history search
• Custom Firebase project initialization
• Better terminal UI using Ink or Blessed
• User registration from CLI
• Configuration file support

🤝 Contributing

Contributions, ideas and feature requests are always welcome.

Feel free to fork the repository and create a pull request.

📄 License

This project is licensed under the ISC License.

👨‍💻 Author

Om Sharma

GitHub

https://github.com/Sharma-Ji-21

If you found this project helpful, consider giving it a ⭐ on GitHub.