🚀 CourseMaster — Backend API

A production-ready, modular REST API for a full-featured online learning platform — built with Express 5, Prisma 7, PostgreSQL, and Advanced AI Orchestration.

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✨ Features

Feature	Description
🤖 AI Chat (RAG)	Context-aware learning assistant using LangChain & OpenRouter
🔍 AI Semantic Search	Intelligent course discovery beyond simple keyword matching
📝 AI Quiz Engine	Automated MCQ generation based on lesson content
🎯 Smart Recs	Category-based course recommendations for personalized learning
🔐 JWT Authentication	Secure signup, login, refresh token flow with HTTP-only cookies
👥 Role-Based Access	student, instructor, admin roles with route-level guards
📚 Course Management	Full CRUD with categories, modules, lessons, search & pagination
💳 Stripe Payments	Checkout sessions, webhook handling for success/fail/refund
📊 Student Progress	Lesson completion tracking with linear unlock progression

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📁 Project Structure

courseMaster-backend/
├── prisma/
│   └── schema.prisma            # Database schema (15+ models)
├── src/
│   ├── index.ts                 # Express app setup, middleware, routes
│   ├── server.ts                # Server bootstrap
│   ├── lib/
│   │   ├── prisma.ts            # Prisma client singleton
│   │   └── stripe.ts            # Stripe client instance
│   └── app/
│       ├── controllers/         # Handles logic for AI, Auth, Courses, etc.
│       ├── services/            # AI logic (LangChain), Prisma queries
│       ├── routes/              # Centralized route definitions
│       ├── middlewares/         # Auth, Role Guards, Error Handlers
│       ├── validations/         # Zod schemas
│       └── utils/               # Helpers (Response format, Async handler)

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🔌 API Endpoints

🤖 AI Services

Method	Endpoint	Description
POST	/api/v1/ai/chat	Chat with the AI Mentor (requires history)
GET	/api/v1/ai/generate-quiz/:lessonId	Generate a 5-question quiz for a lesson
GET	/api/v1/ai/search?query=...	Semantic search with AI insights
GET	/api/v1/ai/recommendations	Get personalized course recommendations

🔐 Auth

Method	Endpoint	Description
POST	/api/v1/auth/signup	Register a new user
POST	/api/v1/auth/login	Login + get JWT tokens
POST	/api/v1/auth/refresh	Refresh access token

📚 Courses & Content

Resource	Endpoints
Courses	/api/v1/courses (CRUD + Progress Tracking)
Enrollments	/api/v1/enrollments (Free/Paid flow)
Submissions	/api/v1/submissions (Assignments & Quizzes)
Payments	/api/webhook (Stripe integration)

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⚡ Quick Start

1. Clone & Install

git clone <repo-url>
cd courseMaster-backend
npm install

2. Environment Variables

Create a .env file:

DATABASE_URL="postgresql://user:password@host:5432/dbname"
JWT_SECRET="your-jwt-secret"
STRIPE_SECRET_KEY="sk_test_..."
STRIPE_WEBHOOK_SECRET="whsec_..."
OPENROUTER_API_KEY="your_openrouter_api_key"
PORT=5000

3. Database Setup

npx prisma db push      # Push schema to database
npx prisma generate      # Generate Prisma Client

4. Run Development Server

npm run dev

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🧠 AI Orchestration (LangChain)

The backend uses LangChain to orchestrate AI workflows:

• Retrieval Augmented Generation (RAG): The AI Mentor fetches relevant course/lesson data from PostgreSQL before generating responses.
• OpenRouter Integration: Flexible LLM support (Gemma, Llama 3, etc.) via a single API.
• Strict Output Parsing: Quizzes are generated as structured JSON for immediate consumption by the frontend.

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🧪 Tech Stack

Technology	Purpose
Express 5	HTTP framework
LangChain	AI Orchestration & RAG
OpenRouter	AI LLM Provider
Prisma 7	ORM + migrations
PostgreSQL	Relational database
Stripe	Payment processing
Zod	Runtime validation
TypeScript 5.9	Type safety

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Built with ❤️ for CourseMaster