LangQuest Backend

A comprehensive language learning platform backend built with Node.js, Express, TypeScript, and Prisma. This API powers interactive language learning experiences with AI-generated content, text-to-speech capabilities, and user progress tracking.

🌐 Live Deployment

Backend URL: https://langquest-backend.onrender.com

🚀 Features

Core Functionality

• AI-Powered Scene Generation: Create interactive language learning scenarios using Google Gemini AI
• Text-to-Speech Integration: Generate audio for script lines using Murf AI
• User Response Tracking: Store and manage user interactions with learning content
• Multi-Language Support: Support for various target languages
• Progress Tracking: Monitor user learning progress and mistakes

API Endpoints

• Scene Management: Create and retrieve learning scenes with script lines
• User Responses: Track user interactions and responses
• Lesson System: Generate and manage lessons with AI-powered content
• Tutorial Progress: Track completion status and user progress

🛠 Tech Stack

• Runtime: Node.js with TypeScript
• Framework: Express.js
• Database: PostgreSQL with Prisma ORM
• AI Integration:
  • Google Gemini AI for content generation
  • Murf AI for text-to-speech
• Database Hosting: Neon (PostgreSQL)
• Deployment: Render

📁 Project Structure

langquest-backend/
├── controllers/           # Business logic controllers
│   └── lesson-controller/ # Lesson generation and management
├── prisma/               # Database schema and migrations
├── routes/               # API route definitions
│   ├── scene.ts         # Scene management endpoints
│   ├── userResponse.ts  # User response tracking
│   └── lesson.ts        # Lesson management
├── utils/               # Utility functions
│   └── prisma.ts       # Database client singleton
├── types/               # TypeScript type definitions
├── prompt/              # AI prompt templates
└── dist/               # Compiled JavaScript (production)

🗄 Database Schema

Core Models

• Scene: Learning scenarios with metadata
• ScriptLine: Individual dialogue lines with TTS audio
• UserResponse: User interactions and responses
• User: User accounts and preferences
• Lesson: AI-generated lesson content
• Tutorial: Learning tutorials and progress tracking

🔧 API Endpoints

Scene Management

POST /scene              # Create new learning scene
GET /scene               # Get latest scene with script lines

User Responses

POST /userResponse       # Record user response to script line
GET /userResponse        # Retrieve all user responses

Lessons

POST /lesson             # Generate new lesson content
GET /lesson/:userId      # Get user's lessons

Health Check

GET /                    # API health check
GET /health              # Detailed health status

🚀 Getting Started

Prerequisites

• Node.js (v18 or higher)
• PostgreSQL database
• Google AI API key
• Murf AI API key

Installation

1. Clone the repository

   git clone https://github.com/Dev-Dhruba/LangQuest-backend.git
   cd LangQuest-backend

2. Install dependencies

   npm install

3. Set up environment variables

   cp env.example .env

   Update .env with your configuration:

   DATABASE_URL="your_postgresql_connection_string"
   GOOGLE_API_KEY="your_google_ai_api_key"
   MURF_API_KEY="your_murf_ai_api_key"
   PORT=8000

4. Set up the database

   npx prisma migrate dev
   npx prisma generate

5. Start development server

   npm run dev

Production Build

npm run build
npm start

🔧 Scripts

• npm run dev - Start development server with hot reload
• npm run build - Build for production
• npm start - Start production server
• npm run prisma:generate - Generate Prisma client
• npm run compile - Compile TypeScript

🌍 Environment Variables

Variable	Description	Required
DATABASE_URL	PostgreSQL connection string	✅
GOOGLE_API_KEY	Google Gemini AI API key	✅
MURF_API_KEY	Murf AI TTS API key	✅
PORT	Server port (default: 8000)	❌
NODE_ENV	Environment (production/development)	❌

📊 Database Migrations

The project uses Prisma for database management:

# Create new migration
npx prisma migrate dev --name migration_name

# Apply migrations
npx prisma migrate deploy

# Reset database (development only)
npx prisma migrate reset

🔒 Security Features

• CORS enabled for cross-origin requests
• Environment variables for sensitive data
• Input validation for API endpoints
• Error handling with detailed logging

🧪 Testing API Endpoints

Create a Scene

curl -X POST https://langquest-backend.onrender.com/scene \
  -H "Content-Type: application/json" \
  -d '{"language": "Korean"}'

Get Latest Scene

curl https://langquest-backend.onrender.com/scene

Record User Response

curl -X POST https://langquest-backend.onrender.com/userResponse \
  -H "Content-Type: application/json" \
  -d '{"scriptLineId": 1, "response": "안녕하세요"}'

🚀 Deployment

Render Deployment

1. Connect GitHub repository to Render
2. Configure build settings:
   • Build Command: npm ci && npx prisma generate && npx tsc
   • Start Command: npm start
3. Add environment variables in Render dashboard
4. Deploy automatically on git push

Manual Deployment

npm run build
npm start

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

📝 API Documentation

Response Format

All API responses follow this structure:

{
  "message": "Success message",
  "data": {...},
  "count": 10 // (for list responses)
}

Error Format

{
  "error": "Error message",
  "details": "Detailed error information"
}

📄 License

This project is licensed under the ISC License.

👨‍💻 Authors

Dev-Dhruba - GitHub Profile

Shreya Shaw - GitHub Profile

🔗 Related Projects

• Frontend Repository: [Add your frontend repo link here]
• Mobile App: [Add your mobile app repo link here]

---

Live API: https://langquest-backend.onrender.com

For questions or support, please open an issue in the GitHub repository.