# AGENTS.md - Coding Guidelines for RagusaIT Web

## Build Commands

```bash
# Development server (port 3000)
npm run dev

# Production build
npm run build

# Preview production build
npm run preview
```

## Test Commands

```bash
# Run all tests
npx vitest

# Run tests in watch mode
npx vitest --watch

# Run tests with coverage
npx vitest --coverage

# Run a single test file
npx vitest src/components/ui/__tests__/Button.test.tsx

# Run tests matching a pattern
npx vitest --grep "Button"

# Run specific test by name
npx vitest -t "passes aria-label to the button element"
```

## Code Style Guidelines

### TypeScript

- Use **strict TypeScript** configuration
- Always define explicit return types for functions
- Use `type` for type definitions, `interface` for object shapes that may be extended
- Avoid `any` - use `unknown` when type is uncertain

### Imports (Order)

1. React imports
2. Third-party libraries (alphabetical)
3. Absolute imports from project (`@/components`, `@/utils`)
4. Relative imports
5. CSS/SCSS imports last

```typescript
import { useState, useEffect } from 'react';
import { motion } from 'motion/react';
import { Link } from 'react-router-dom';
import { useTranslation } from '../../i18n';
import { debounce } from '../../utils/debounce';
import styles from './Navbar.module.css';
```

### Component Structure

- Use **named exports** for all components
- Props interface should be named `[ComponentName]Props`
- Place props interface immediately before component
- Use CSS Modules for styling (`.module.css`)
- Destructure props in function signature with defaults

```typescript
interface ButtonProps extends ButtonHTMLAttributes<HTMLButtonElement> {
  variant?: 'primary' | 'secondary' | 'outline';
  size?: 'sm' | 'md' | 'lg';
  isLoading?: boolean;
}

export function Button({
  variant = 'primary',
  size = 'md',
  isLoading = false,
  children,
  ...props
}: ButtonProps) {
  // Implementation
}
```

### Naming Conventions

- **Components**: PascalCase (e.g., `Navbar`, `Button`)
- **Hooks**: camelCase with `use` prefix (e.g., `useRateLimit`, `useTypingEffect`)
- **Utilities**: camelCase (e.g., `debounce`, `formatDate`)
- **Types/Interfaces**: PascalCase (e.g., `ButtonProps`, `Translations`)
- **Constants**: UPPER_SNAKE_CASE for module-level constants
- **Files**: Match default export name (e.g., `Navbar.tsx` exports `Navbar`)

### Error Handling

- Use try-catch for async operations
- Provide meaningful error messages
- Use early returns to avoid nested conditionals
- Clean up resources (timers, event listeners) in useEffect cleanup

```typescript
useEffect(() => {
  const handleScroll = () => {
    if (!ticking) {
      window.requestAnimationFrame(() => {
        setIsScrolled(window.scrollY > 20);
        ticking = false;
      });
      ticking = true;
    }
  };
  window.addEventListener('scroll', handleScroll, { passive: true });
  return () => window.removeEventListener('scroll', handleScroll);
}, []);
```

### Testing

- Add `// @vitest-environment jsdom` at top of test files
- Use `describe` and `it` blocks with descriptive names
- Clean up after each test with `cleanup()` from testing-library
- Mock external dependencies appropriately
- Test behavior, not implementation

```typescript
// @vitest-environment jsdom
import { render, screen, cleanup } from '@testing-library/react';
import { describe, it, expect, afterEach } from 'vitest';

describe('Button', () => {
  afterEach(() => {
    cleanup();
  });

  it('renders with correct aria-label', () => {
    render(<Button aria-label="Submit">Click</Button>);
    expect(screen.getByRole('button', { name: /submit/i })).toBeTruthy();
  });
});
```

### Performance

- Use `React.lazy()` for code splitting on routes
- Memoize expensive calculations with `useMemo`
- Use `requestAnimationFrame` for scroll/resize handlers
- Debounce expensive operations (use `debounce` utility)
- Add `will-change` CSS sparingly for GPU acceleration

### Accessibility

- Always include meaningful `aria-label` for interactive elements
- Use semantic HTML elements (`<header>`, `<nav>`, `<main>`)
- Ensure keyboard navigation works
- Test with screen readers

### Project Structure

```
src/
├── components/
│   ├── effects/       # Visual effects (WebGL, animations)
│   ├── layout/        # Layout components (Navbar, Footer)
│   ├── sections/      # Page sections (Hero, Services)
│   └── ui/            # Reusable UI components (Button, Input)
├── hooks/             # Custom React hooks
├── i18n/              # Internationalization (de.ts, en.ts)
├── pages/             # Route components
├── styles/            # Global styles
└── utils/             # Utility functions
```

### State Management

- Use React Context for global state (e.g., i18n)
- Prefer local state when possible
- Use `useRef` for DOM references and mutable values
- Store user preferences in localStorage with proper keys

### Comments

- Use JSDoc for exported functions
- Explain "why" not "what" in comments
- Keep comments concise and meaningful