# Interview Quiz Application - Backend

MySQL + Express + Node.js Backend API

## Project Structure

```
backend/
├── config/          # Configuration files (database, etc.)
├── controllers/     # Request handlers
├── middleware/      # Custom middleware (auth, validation, etc.)
├── models/          # Sequelize models
├── routes/          # API route definitions
├── migrations/      # Database migrations
├── seeders/         # Database seeders
├── tests/           # Test files
├── server.js        # Main application entry point
├── .env             # Environment variables (not in git)
├── .env.example     # Environment variables template
└── package.json     # Dependencies and scripts
```

## Prerequisites

- Node.js 18+ 
- MySQL 8.0+
- npm or yarn

## Installation

1. **Navigate to backend directory:**
   ```bash
   cd backend
   ```

2. **Install dependencies:**
   ```bash
   npm install
   ```

3. **Setup environment variables:**
   ```bash
   cp .env.example .env
   ```
   Then edit `.env` with your database credentials.

4. **Create MySQL database:**
   ```sql
   CREATE DATABASE interview_quiz_db CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
   ```

## Running the Application

### Development Mode
```bash
npm run dev
```
Uses nodemon for auto-restart on file changes.

### Production Mode
```bash
npm start
```

### Server will start on:
- **URL:** http://localhost:3000
- **API Endpoint:** http://localhost:3000/api
- **Health Check:** http://localhost:3000/health

## Database Management

### Initialize Sequelize
```bash
npx sequelize-cli init
```

### Run Migrations
```bash
npm run migrate
```

### Undo Last Migration
```bash
npm run migrate:undo
```

### Run Seeders
```bash
npm run seed
```

### Undo Seeders
```bash
npm run seed:undo
```

## Testing

### Run all tests
```bash
npm test
```

### Run tests in watch mode
```bash
npm run test:watch
```

## API Endpoints

Coming soon... (Will be documented as features are implemented)

### Authentication
- `POST /api/auth/register` - Register new user
- `POST /api/auth/login` - Login user
- `POST /api/auth/logout` - Logout user
- `GET /api/auth/verify` - Verify JWT token

### Categories
- `GET /api/categories` - Get all categories
- `GET /api/categories/:id` - Get category by ID

### Questions
- `GET /api/questions/category/:categoryId` - Get questions by category
- `GET /api/questions/:id` - Get question by ID
- `GET /api/questions/search` - Search questions

### Quiz
- `POST /api/quiz/start` - Start quiz session
- `POST /api/quiz/submit` - Submit answer
- `POST /api/quiz/complete` - Complete quiz session
- `GET /api/quiz/session/:sessionId` - Get session details

### User Dashboard
- `GET /api/users/:userId/dashboard` - Get user dashboard
- `GET /api/users/:userId/history` - Get quiz history
- `PUT /api/users/:userId` - Update user profile

### Admin
- `GET /api/admin/statistics` - Get system statistics
- `GET /api/admin/guest-settings` - Get guest settings
- `PUT /api/admin/guest-settings` - Update guest settings

## Environment Variables

| Variable | Description | Default |
|----------|-------------|---------|
| `NODE_ENV` | Environment (development/production) | development |
| `PORT` | Server port | 3000 |
| `API_PREFIX` | API route prefix | /api |
| `DB_HOST` | MySQL host | localhost |
| `DB_PORT` | MySQL port | 3306 |
| `DB_NAME` | Database name | interview_quiz_db |
| `DB_USER` | Database user | root |
| `DB_PASSWORD` | Database password | - |
| `JWT_SECRET` | Secret key for JWT tokens | - |
| `JWT_EXPIRE` | JWT expiration time | 24h |
| `CORS_ORIGIN` | Allowed CORS origin | http://localhost:4200 |

## Development Workflow

1. **Create a feature branch**
   ```bash
   git checkout -b feature/your-feature-name
   ```

2. **Implement your feature**
   - Follow the tasks in `BACKEND_TASKS.md`
   - Write tests for your code
   - Update this README if needed

3. **Test your changes**
   ```bash
   npm test
   ```

4. **Commit and push**
   ```bash
   git add .
   git commit -m "feat: your feature description"
   git push origin feature/your-feature-name
   ```

## Technologies Used

- **Express.js** - Web framework
- **Sequelize** - ORM for MySQL
- **MySQL2** - MySQL driver
- **JWT** - Authentication
- **Bcrypt** - Password hashing
- **Helmet** - Security headers
- **CORS** - Cross-origin resource sharing
- **Morgan** - HTTP request logger
- **Express Validator** - Input validation
- **Express Rate Limit** - Rate limiting
- **Jest** - Testing framework
- **Supertest** - API testing

## Testing Database Connection

To test the database connection:

```bash
npm run test:db
```

This will verify:
- MySQL server is running
- Database credentials are correct
- Database exists
- Connection is successful

## Environment Configuration

All environment variables are validated on server startup. To manually validate:

```bash
npm run validate:env
```

To generate a new JWT secret:

```bash
npm run generate:jwt
```

See [ENVIRONMENT_GUIDE.md](./ENVIRONMENT_GUIDE.md) for complete configuration documentation.

## Testing Models

To test the User model:

```bash
npm run test:user
```

This verifies:
- User creation with UUID
- Password hashing
- Password comparison
- Validation rules
- Helper methods

## Next Steps

Follow the tasks in `BACKEND_TASKS.md`:
- ✅ Task 1: Project Initialization (COMPLETED)
- ✅ Task 2: Database Setup (COMPLETED)
- ✅ Task 3: Environment Configuration (COMPLETED)
- ✅ Task 4: Create User Model & Migration (COMPLETED)
- 🔄 Task 5: Create Categories Model & Migration (NEXT)
- ... and more

## Documentation References

- [BACKEND_TASKS.md](../BACKEND_TASKS.md) - Complete task list
- [SEQUELIZE_QUICK_REFERENCE.md](../SEQUELIZE_QUICK_REFERENCE.md) - Code examples
- [SAMPLE_MIGRATIONS.md](../SAMPLE_MIGRATIONS.md) - Migration templates
- [interview_quiz_user_story.md](../interview_quiz_user_story.md) - Full specification

## License

ISC