🚀 LeetCode Platform - Problem Solving & Learning Hub

📚 Description

LeetCode Platform is a comprehensive coding challenge platform that provides users with an interactive environment to solve algorithmic problems, track their progress, and enhance their coding skills. This platform combines the best features of coding platforms with AI-powered assistance and video tutorial integration.

Key Benefits:

• 🎯 Structured coding challenges with multiple difficulty levels
• 🤖 AI-powered doubt resolution and learning assistance
• 📹 Integrated video tutorial system for better learning
• 📊 Comprehensive progress tracking and user statistics
• 🔐 Secure authentication with role-based access control
• ⚡ High-performance caching with Redis for optimal user experience

🛠️ Tech Stack

Backend Technologies

• Runtime: Node.js (v18+)
• Framework: Express.js
• Database: MongoDB with Mongoose
• Cache: Redis
• Authentication: JWT + Express Sessions
• File Storage: Cloudinary (for video content)
• Rate Limiting: Express Rate Limit + Redis
• AI Integration: Google Generative AI (@google/genai)

Development Tools

• Script Runner: Nodemon (development)
• Environment Management: dotenv
• Input Validation: validator.js
• Security: bcrypt, cors, cookie-parser

✨ Features

👥 User Management

• ✅ User Registration & Login: Secure authentication system
• 👤 Profile Management: Complete user profile CRUD operations
• 🔐 Role-based Access: Admin and regular user roles
• 📊 User Statistics: Track solved problems and performance metrics

🧩 Problem Management

• 📝 Problem Creation: Admin can create coding challenges
• 🏷️ Categorized Problems: Easy, Medium, Hard difficulty levels
• 🏷️ Tagged Content: Array, LinkedList, DP, Graph, String, Stack, Queue, Heap, Tree
• 🧪 Test Cases: Visible and hidden test cases for comprehensive evaluation
• 💻 Multi-language Support: Initial code templates and reference solutions

🔄 Code Execution & Submission

• ▶️ Code Running: Test your code against visible test cases
• ✍️ Code Submission: Submit solutions for evaluation
• 📈 Execution Results: Detailed feedback on submission performance
• ⚡ Rate Limiting: Prevents abuse with intelligent submission throttling

🤖 AI-Powered Learning

• 🧠 Doubt Resolution: AI chatbot for instant problem-solving assistance
• 💡 Learning Guidance: Contextual help for algorithmic challenges
• 🔍 Smart Responses: Google Generative AI integration for accurate solutions

🎥 Video Tutorial System

• 📹 Video Content: Upload and manage educational video content
• 🔗 Problem Integration: Link videos to specific coding problems
• ☁️ Cloud Storage: Secure video hosting with Cloudinary
• 🗑️ Content Management: Admin controls for video content lifecycle

🔒 Security & Performance

• 🛡️ JWT Authentication: Secure token-based authentication
• 🍪 Session Management: Express sessions with secure cookie handling
• 🚫 CORS Protection: Cross-origin request security
• ⚡ Redis Caching: Enhanced performance with intelligent caching
• 🚦 Rate Limiting: Prevents API abuse and ensures fair usage

🚀 Installation Guide

Prerequisites

• Node.js (v18 or higher)
• MongoDB (local or cloud instance)
• Redis server
• npm or yarn package manager

Step-by-Step Setup

1. Clone the Repository

   git clone <your-repository-url>
   cd Leetcode✅

2. Install Dependencies

   npm install

3. Environment Configuration Create a .env file in the root directory:

   # Database Configuration
   MONGODB_URI=mongodb://localhost:27017/leetcode-platform
   REDIS_URL=redis://localhost:6379
   
   # Server Configuration
   PORT=5000
   SESSION_SECRET=your-super-secret-session-key
   
   # JWT Configuration
   JWT_SECRET=your-jwt-secret-key
   
   # AI Configuration
   GOOGLE_AI_API_KEY=your-google-ai-api-key
   
   # Cloudinary Configuration (for video uploads)
   CLOUDINARY_CLOUD_NAME=your-cloudinary-name
   CLOUDINARY_API_KEY=your-cloudinary-api-key
   CLOUDINARY_API_SECRET=your-cloudinary-secret

4. Start Development Server

   npm run dev

5. Verify Installation Visit http://localhost:5000/test to confirm the backend is running successfully.

📖 Usage

Starting the Application

# Development mode (with auto-restart)
npm run dev

# Production mode
npm start

Basic API Usage

1. Register a new user:

   curl -X POST http://localhost:5000/user/register \
     -H "Content-Type: application/json" \
     -d '{"firstName":"John","lastName":"Doe","email":"john@example.com","password":"password123"}'

2. Login:

   curl -X POST http://localhost:5000/user/login \
     -H "Content-Type: application/json" \
     -d '{"email":"john@example.com","password":"password123"}'

3. Get all problems:

   curl -X GET http://localhost:5000/problem/getAllProblem \
     -H "Authorization: Bearer YOUR_JWT_TOKEN"

📸 Screenshot Placeholder: Add application screenshots here

📁 Folder Structure

Leetcode✅/
├── src/                          # Source code
│   ├── controller/               # Route controllers
│   │   ├── ai.controller.js      # AI chatbot functionality
│   │   ├── problem.controller.js # Problem management
│   │   ├── submission.controller.js # Code execution & submission
│   │   ├── user.controller.js    # User authentication & management
│   │   └── video.controller.js   # Video content management
│   ├── middleware/               # Custom middleware
│   │   ├── adminMiddleware.js    # Admin role verification
│   │   ├── redisRateLimiter.js   # Request rate limiting
│   │   └── userMiddleware.js     # User authentication
│   ├── model/                    # Database models
│   │   ├── problem.js           # Problem schema
│   │   ├── solutionVideo.js      # Video metadata schema
│   │   ├── submission.js         # Submission schema
│   │   └── user.js              # User schema
│   ├── routes/                   # API route definitions
│   │   ├── ai.js                # AI chatbot routes
│   │   ├── problemCreator.js     # Problem CRUD routes
│   │   ├── submission.js         # Code execution routes
│   │   ├── userAuth.js           # Authentication routes
│   │   └── videoCreator.js      # Video management routes
│   ├── config/                   # Configuration files
│   │   ├── db.js                # MongoDB connection
│   │   └── redis.js             # Redis connection
│   ├── utils/                    # Utility functions
│   │   ├── problemUtility.js     # Problem-specific utilities
│   │   └── validator.js          # Input validation utilities
│   └── index.js                  # Application entry point
├── node_modules/                 # Dependencies
├── package.json                  # Project configuration
├── package-lock.json            # Dependency lock file
└── README.md                    # Project documentation

🔗 API Endpoints

Authentication (/user)

Method	Endpoint	Description	Auth Required
POST	/user/register	Register a new user	No
POST	/user/login	User login	No
POST	/user/logout	User logout	Yes
GET	/user/check	Verify user session	Yes
GET	/user/getProfile	Get user profile	Yes
PUT	/user/updateProfile	Update user profile	Yes
DELETE	/user/deleteProfile	Delete user account	Yes
POST	/user/admin/register	Admin registration	Admin

Problem Management (/problem)

Method	Endpoint	Description	Auth Required
POST	/problem/create	Create new problem	Admin
PUT	/problem/update/:id	Update problem	Admin
DELETE	/problem/delete/:id	Delete problem	Admin
GET	/problem/getProblem/:id	Get problem by ID	Yes
GET	/problem/getAllProblem	Get all problems	Yes
GET	/problem/userProblem	Get user's solved problems	Yes
GET	/problem/submittedProblem/:pid	Get submission history	Yes
GET	/problem/userStats	Get user statistics	Yes

Code Submission (/submission)

Method	Endpoint	Description	Auth Required
POST	/submission/run/:id	Run code against visible test cases	Yes
POST	/submission/submit/:id	Submit code for evaluation	Yes

AI Assistant (/ai)

Method	Endpoint	Description	Auth Required
POST	/ai/chat	Chat with AI for doubt resolution	Yes

Video Management (/video)

Method	Endpoint	Description	Auth Required
GET	/video/create/:id	Generate upload signature	Admin
POST	/video/save	Save video metadata	Admin
DELETE	/video/delete/:videoId	Delete video content	Admin

🤝 Contributing

We welcome contributions! Please follow these steps:

Getting Started

1. Fork the repository
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Make your changes and test thoroughly
4. Commit with descriptive messages: git commit -m 'Add amazing feature'
5. Push to your branch: git push origin feature/amazing-feature
6. Open a Pull Request

Development Guidelines

• 📝 Follow existing code style and conventions
• 🧪 Write tests for new features
• 📚 Update documentation for API changes
• 🔍 Test your changes locally before submitting
• 💡 Ensure backward compatibility for existing APIs

Code Standards

• Use ESLint for code formatting
• Write descriptive commit messages
• Add JSDoc comments for new functions
• Follow RESTful API design principles

👨‍💻 Contact / Author

Developer: Vipul Kumar
Email: vipulvipul65845@gmail.com

Connect with me:

• 🐙 GitHub: @vipulkumar
• 💼 LinkedIn: linkedin.com/in/vipulkumar
• 🌐 Portfolio: vipulkumar.dev
• 📧 Email: vipulvipul65845@gmail.com

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