# Development Guide

## 🚀 Quick Start for Developers

### Prerequisites
- Node.js 14+
- PostgreSQL 12+
- VS Code (recommended) with extensions:
  - ES7+ React/Redux/React-Native snippets
  - Tailwind CSS IntelliSense
  - PostgreSQL Explorer

### Initial Setup

```bash
# 1. Clone repository
git clone <repo-url>
cd pg-admin

# 2. Install dependencies
npm install

# 3. Create .env from example
cp .env.example .env

# 4. Configure your database
# Edit .env with your PostgreSQL credentials

# 5. Start development server
npm run dev
```

Open http://localhost:3000

## 📝 Coding Standards

### JavaScript/Frontend

```javascript
// Use const by default, let for loops
const config = { ... };
let accumulator = 0;

// Arrow functions for callbacks
const handleClick = (e) => { ... };

// Use template literals
const message = `Hello ${name}`;

// Async/await instead of .then()
const data = await api.fetchUsers();

// Error handling
try {
    await api.call();
} catch (error) {
    console.error('Error:', error);
    showError(error.message);
}
```

### CSS

```css
/* Use Tailwind classes */
<button class="px-4 py-2 bg-blue-600 text-white rounded-lg hover:bg-blue-700">

/* Create custom utility classes in main.css */
.card {
    @apply bg-white dark:bg-slate-900 border border-slate-200 rounded-xl shadow-sm;
}

/* Use CSS custom properties for theming */
:root {
    --color-primary: #3b82f6;
    --color-success: #10b981;
}

.dark {
    --color-primary: #60a5fa;
}
```

### SQL

```sql
-- Use parameterized queries to prevent SQL injection
pool.query('SELECT * FROM users WHERE id = $1', [userId]);

-- Use clear naming conventions
SELECT user_id, created_at FROM activity_logs ORDER BY created_at DESC;

-- Create indexes for frequently queried columns
CREATE INDEX idx_activity_logs_user_id ON activity_logs(user_id);
```

## 🏗️ Adding New Features

### Adding a New Module

1. **Create module structure**
```
public/modules/new-feature/
├── new-feature.html      # UI template
├── styles/
│   └── new-feature.css  # Styles (optional)
└── js/
    └── new-feature.js   # Logic (optional)
```

2. **Update router.js**
```javascript
routes: {
    'new-feature': { 
        module: 'newFeatureModule', 
        requireAuth: true, 
        handler: this.handleNewFeature.bind(this) 
    }
}
```

3. **Add navigation item**
```html
<a href="#new-feature" class="nav-item">
    <i data-lucide="icon" class="w-5 h-5"></i>
    <span>New Feature</span>
</a>
```

### Adding a New API Endpoint

1. **Create route file** in `src/routes/`

```javascript
module.exports = (pool) => {
    const router = express.Router();
    
    const requireAuth = (req, res, next) => {
        if (req.session && req.session.userId) {
            next();
        } else {
            res.status(401).json({ success: false });
        }
    };
    
    // GET endpoint
    router.get('/', requireAuth, async (req, res) => {
        try {
            const result = await pool.query('SELECT * FROM table');
            res.json({ success: true, data: result.rows });
        } catch (error) {
            res.status(500).json({ success: false, error: error.message });
        }
    });
    
    return router;
};
```

2. **Register in server.js**
```javascript
app.use('/api/endpoint', require('./src/routes/endpoint')(pool));
```

3. **Add API method** in `public/js/api.js`
```javascript
async getEndpoint() {
    return this.request('/endpoint', { method: 'GET' });
}
```

## 🐛 Debugging

### Frontend Debugging

```javascript
// Use Chrome DevTools
// F12 → Sources tab for breakpoints

// Use console methods
console.log('Value:', value);         // Info
console.error('Error:', error);       // Error
console.warn('Warning:', warning);    // Warning
console.table(array);                 // Table view

// Use debugger statement
debugger;  // Pauses execution when DevTools open
```

### Backend Debugging

```javascript
// Use node --inspect for debugging
node --inspect server.js

// Or use VS Code debugger with .vscode/launch.json
{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "launch",
            "program": "${workspaceFolder}/server.js",
            "restart": true,
            "console": "integratedTerminal"
        }
    ]
}
```

### Database Debugging

```bash
# Connect to PostgreSQL
psql -U postgres -d postgres -h localhost

# Useful queries
\dt                     # List tables
\d users                # Describe table
SELECT COUNT(*) FROM table_name;
EXPLAIN ANALYZE SELECT ...;
```

## 📊 Testing API

### Using curl

```bash
# Register
curl -X POST http://localhost:3000/api/auth/register \
  -H "Content-Type: application/json" \
  -d '{"name":"Test","email":"test@example.com","password":"pass123"}'

# Login
curl -X POST http://localhost:3000/api/auth/login \
  -H "Content-Type: application/json" \
  -d '{"email":"test@example.com","password":"pass123"}'

# Get data
curl http://localhost:3000/api/db/tables

# Execute query
curl -X POST http://localhost:3000/api/db/query \
  -H "Content-Type: application/json" \
  -d '{"sql":"SELECT COUNT(*) FROM users"}'
```

### Using Postman

1. Import requests from `postman_collection.json` (если имеется)
2. Set base URL: `http://localhost:3000`
3. Save responses in collection

## 🗂️ File Organization

**Keep related files together:**
- HTML structure
- CSS styling  
- JavaScript logic

**Example - Auth Module:**
```
modules/auth/
├── login.html       # Structure + CSS
└── (js in main app.js or auth.js)
```

**Avoid:**
- Mixing concerns (HTML with business logic)
- Creating orphaned files
- Dead code without comments

## 📚 Best Practices

### General

1. **DRY (Don't Repeat Yourself)**
   - Extract common functions to utilities
   - Create reusable components

2. **KISS (Keep It Simple, Stupid)**
   - Write clear, readable code
   - Avoid over-engineering

3. **SOLID Principles**
   - Single responsibility
   - Open/closed (open for extension, closed for modification)

### Frontend

1. **Performance**
   - Lazy load modules when possible
   - Minimize DOM manipulation
   - Use event delegation for dynamic elements

2. **Accessibility**
   - Use semantic HTML
   - Add ARIA labels where needed
   - Test with keyboard navigation

3. **Responsive Design**
   - Mobile-first approach
   - Test on multiple devices
   - Use relative units (rem, %, vw)

### Backend

1. **Database**
   - Always use parameterized queries
   - Create appropriate indexes
   - Regular backups

2. **Security**
   - Validate all inputs
   - Hash passwords properly
   - Use HTTPS in production
   - Implement rate limiting

3. **Error Handling**
   - Provide meaningful error messages
   - Log errors server-side
   - Don't expose sensitive information

## 🔑 Environment Variables

Never commit `.env`! Use `.env.example` template.

```bash
# Required for all environments
PORT=3000
DB_HOST=localhost
DB_USER=postgres

# Development only
NODE_ENV=development
DEBUG=*

# Production only (set via deployment system)
SESSION_SECRET=production-secret
SSL_CERT=/path/to/cert.pem
```

## 📦 Dependencies

### Why we use them

- **express** - Web framework
- **pg** - PostgreSQL driver
- **bcryptjs** - Password hashing
- **express-session** - Session management
- **cors** - Cross-origin requests
- **dotenv** - Environment variables

**Keeping dependencies updated:**
```bash
npm outdated              # Check for updates
npm update               # Update to latest
npm audit                # Check for vulnerabilities
npm audit fix           # Auto-fix vulnerabilities
```

## 🚀 Performance Tips

1. **Frontend**
   - Use production builds
   - Minify CSS/JS
   - Lazy load images
   - Use CSS containment for heavy animations

2. **Backend**
   - Use connection pooling
   - Add database indexes
   - Cache frequently accessed data
   - Optimize queries with EXPLAIN

3. **Deployment**
   - Use CDN for static files
   - Enable gzip compression
   - Set appropriate cache headers
   - Use monitoring tools

## 📖 Further Reading

- [Express.js Documentation](https://expressjs.com/)
- [PostgreSQL Documentation](https://www.postgresql.org/docs/)
- [MDN Web Docs](https://developer.mozilla.org/)
- [Node.js Best Practices](https://github.com/goldbergyoni/nodebestpractices)

---

Last updated: January 2024