PairCode 🚀

Real-Time Collaborative IDE with Gemini AI Review

PairCode is a full-stack web application where developers can collaborate in a shared code editor in real time, get instant AI-powered code review via Google Gemini and execute code in a secure sandbox — all in the browser.

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✨ Features

🤝 Real-Time Collaboration

• Multiple developers join a shared room using a unique Room ID
• Code changes, language switches, and cursor positions sync instantly across all participants
• Shared notepad panel for taking notes together during a session
• Live user presence list with join/leave notifications

🤖 Gemini AI Code Review

• Click "AI Review" to instantly analyze your code with Google Gemini 2.5 Flash
• Detects bugs, complexity issues, and style violations
• Returns structured feedback: bugs, suggestions, quality rating (1–10), and a summary
• Review results auto-saved to your history (when logged in)

💬 Gemini AI Chat Panel

• Persistent multi-turn chatbot sidebar in the editor
• Automatically aware of the current code in the editor buffer
• Surfaces AI Review results directly in the chat conversation

⚡ Secure Code Execution

• Run code right in the browser via Judge0 sandboxed execution
• Supports Python, JavaScript, and Java
• Execution output is broadcast to all room members simultaneously

🔐 Authentication

• Email/password registration & login
• Google OAuth 2.0 sign-in
• JWT-based stateless authentication (7-day expiry)

📊 Dashboard & History

• View all past AI review sessions with ratings and timestamps
• Replay any past review's full feedback
• Delete individual history entries

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🛠️ Tech Stack

Frontend

Technology	Purpose
React 19	UI framework
Vite	Build tool & dev server
React Router DOM v7	Client-side routing
Socket.IO Client	Real-time communication
CodeMirror 5	Embedded code editor
React Hot Toast	Notifications
Vanilla CSS	Styling

Backend

Technology	Purpose
Node.js + Express 5	REST API server
Socket.IO	WebSocket server
MongoDB + Mongoose	Database & ODM
Passport.js	Authentication strategies
JWT	Stateless auth tokens
bcryptjs	Password hashing
Google Gemini API	AI code review & chat
Judge0 API	Sandboxed code execution

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🏗️ Project Structure

PairCode/
├── server.js               # Express + Socket.IO server (all real-time logic)
├── Actions.js              # Socket event name constants
├── vite.config.js          # Vite configuration
│
├── routes/
│   ├── auth.js             # Register, login, Google OAuth
│   ├── review.js           # Gemini AI code review
│   ├── chat.js             # Gemini AI multi-turn chat
│   ├── history.js          # User session history CRUD
│
├── models/
│   ├── User.js             # User schema
│   ├── Session.js          # AI review history schema
│
├── middleware/
│   └── authMiddleware.js   # JWT verification middleware
│
└── src/                    # React frontend (Vite)
    ├── main.jsx            # Entry point
    ├── App.jsx             # Router & global layout
    ├── socket.js           # Socket.IO client singleton
    │
    ├── context/
    │   └── AuthContext.jsx # Global auth state (user, token, login, logout)
    │
    ├── pages/
    │   ├── LandingPage.jsx     # Marketing homepage
    │   ├── HomePage.jsx        # Join/create room
    │   ├── EditorPage.jsx      # Collaborative code editor
    │   ├── Dashboard.jsx       # User profile & review history
            │   ├── Login.jsx
    │   └── Register.jsx
    │
    └── Components/
        ├── Editor.jsx          # CodeMirror wrapper
        ├── AIChatPanel.jsx     # Gemini AI chat sidebar
        ├── NotepadPanel.jsx    # Shared notepad
        ├── ReviewPanel.jsx     # Displays AI review result
        ├── Client.jsx          # User avatar component
        └── ProtectedRoute.jsx  # Auth guard

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⚙️ Getting Started

Prerequisites

• Node.js v18+
• MongoDB (local or Atlas URI)
• Google Gemini API Key
• Google OAuth Credentials

1. Clone the Repository

git clone https://github.com/Jaykolate/PairCode.git
cd PairCode

2. Install Dependencies

npm install

3. Configure Environment Variables

Create a .env file in the project root:

# MongoDB
MONGO_URI=mongodb://localhost:27017/paircode

# JWT
JWT_SECRET=your_super_secret_jwt_key

# Google Gemini AI
GEMINI_API_KEY=your_gemini_api_key

# Google OAuth
GOOGLE_CLIENT_ID=your_google_client_id
GOOGLE_CLIENT_SECRET=your_google_client_secret

# URLs
VITE_BACKEND_URL=http://localhost:10000
VITE_FRONTEND_URL=http://localhost:5173

# Server Port
PORT=10000

5. Run the Application

Development mode (run both simultaneously):

# Terminal 1 — Start the backend server
npm run server:dev

# Terminal 2 — Start the Vite frontend
npm run dev

Production mode:

npm run build
npm run server:prod

The frontend is served as static files from the Express server at http://localhost:10000.

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🔌 API Reference

Method	Endpoint	Auth Required	Description
POST	/api/auth/register	No	Create a new account
POST	/api/auth/login	No	Login, receive JWT
GET	/api/auth/google	No	Start Google OAuth flow
POST	/api/review	Optional	Run Gemini AI code review
POST	/api/chat	No	Send a message to Gemini AI chat
GET	/api/history	Yes	Get user's review history
DELETE	/api/history/:id	Yes	Delete a review session

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🔄 How Real-Time Works

Collaborative Editor

User types code
    → emits CODE_CHANGE (via Socket.IO)
    → Server broadcasts to all others in the room
    → Their editors update instantly

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🛣️ Routes

Path	Page	Auth
/	Landing Page	No
/join	Create / Join Room	No
/editor/:roomId	Collaborative Editor	No
/login	Login	No
/register	Register	No
/dashboard	User Dashboard	✅ Yes

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📦 Scripts

Command	Description
npm run dev	Start Vite frontend dev server
npm run server:dev	Start backend with nodemon (auto-reload)
npm run server:prod	Start backend in production mode
npm run build	Build frontend for production
npm run lint	Run ESLint

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🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/your-feature
3. Commit your changes: git commit -m 'Add some feature'
4. Push to the branch: git push origin feature/your-feature
5. Open a Pull Request

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📄 License

This project is open source. See the LICENSE file for details.

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Built with ❤️ using React, Node.js, Socket.IO, and Google Gemini AI