# Route Protection and Access Control Implementation

This document describes the comprehensive route protection and access control system implemented for the car maintenance management system.

## Overview

The route protection system provides:
- **Authentication middleware** for all protected routes
- **Role-based access control** (RBAC) with three levels: Superadmin, Admin, User
- **Automatic redirection** for unauthorized access attempts
- **Session validation** and user status checking
- **Route-specific protection** functions
- **Permission checking** utilities
- **Redirect authenticated users** from auth pages (signin/signup)

## Authentication Levels

The system uses a hierarchical authentication system where lower numbers indicate higher privileges:

| Level | Name       | Value | Description                           |
|-------|------------|-------|---------------------------------------|
| 1     | Superadmin | 1     | Full system access, can manage admins |
| 2     | Admin      | 2     | Can manage users and business data    |
| 3     | User       | 3     | Basic access to operational features  |

## Route Protection Matrix

| Route                    | Auth Required | Min Level | Superadmin | Admin | User |
|--------------------------|---------------|-----------|------------|-------|------|
| `/dashboard`             | ✓             | User (3)  | ✓          | ✓     | ✓    |
| `/users`                 | ✓             | Admin (2) | ✓          | ✓     | ✗    |
| `/customers`             | ✓             | User (3)  | ✓          | ✓     | ✓    |
| `/vehicles`              | ✓             | User (3)  | ✓          | ✓     | ✓    |
| `/maintenance-visits`    | ✓             | User (3)  | ✓          | ✓     | ✓    |
| `/financial`             | ✓             | Admin (2) | ✓          | ✓     | ✗    |
| `/admin/enable-signup`   | ✓             | Super (1) | ✓          | ✗     | ✗    |
| `/signin`                | ✗             | None      | ✓*         | ✓*    | ✓*   |
| `/signup`                | ✗             | None      | ✓*         | ✓*    | ✓*   |

*\* Authenticated users are redirected away from auth pages*

## Implementation Details

### Core Middleware Functions

#### `requireAuthentication(request, options?)`
- Ensures user is logged in and active
- Options: `allowInactive`, `redirectTo`
- Redirects to `/signin` if not authenticated
- Checks user status (active/inactive)

#### `requireAdmin(request, options?)`
- Requires Admin level (2) or higher
- Calls `requireAuthLevel` with `AUTH_LEVELS.ADMIN`

#### `requireSuperAdmin(request, options?)`
- Requires Superadmin level (1)
- Calls `requireAuthLevel` with `AUTH_LEVELS.SUPERADMIN`

#### `redirectIfAuthenticated(request, redirectTo?)`
- Redirects authenticated users away from auth pages
- Default redirect: `/dashboard`
- Only redirects active users

### Route-Specific Protection Functions

#### `protectUserManagementRoute(request)`
- Used by `/users` route
- Requires Admin level or higher
- Additional business logic validation

#### `protectFinancialRoute(request)`
- Used by `/financial` route
- Requires Admin level or higher

#### `protectCustomerRoute(request)`
- Used by `/customers` route
- Requires any authenticated user

#### `protectVehicleRoute(request)`
- Used by `/vehicles` route
- Requires any authenticated user

#### `protectMaintenanceRoute(request)`
- Used by `/maintenance-visits` route
- Requires any authenticated user

### Permission Checking

#### `checkPermission(user, permission)`
Checks specific permissions for a user:

| Permission        | Superadmin | Admin | User |
|-------------------|------------|-------|------|
| `view_all_users`  | ✓          | ✗     | ✗    |
| `create_users`    | ✓          | ✓     | ✗    |
| `manage_finances` | ✓          | ✓     | ✗    |
| `view_reports`    | ✓          | ✓     | ✗    |

### Session Validation

#### `validateSession(request)`
Returns session validation result:
```typescript
{
  isValid: boolean;
  user: SafeUser | null;
  error?: 'no_user' | 'inactive_user' | 'session_error';
}
```

### Error Handling

#### `createUnauthorizedResponse(message?)`
- Creates 403 Forbidden response
- Default message in Arabic
- Custom message support

## Usage Examples

### Protecting a Route
```typescript
// In route loader
export async function loader({ request }: LoaderFunctionArgs) {
  const user = await requireAdmin(request);
  return json({ user });
}
```

### Custom Protection
```typescript
// In route loader with custom options
export async function loader({ request }: LoaderFunctionArgs) {
  const user = await requireAuthentication(request, {
    redirectTo: "/custom-login",
    allowInactive: false
  });
  return json({ user });
}
```

### Permission Checking
```typescript
// In component or route
const canManageUsers = checkPermission(user, 'create_users');
if (canManageUsers) {
  // Show user management UI
}
```

### Conditional Access Control
```typescript
// Signup route with conditional access
export async function loader({ request }: LoaderFunctionArgs) {
  await redirectIfAuthenticated(request);
  
  const signupAllowed = await isSignupAllowed();
  if (!signupAllowed && !adminOverride) {
    return redirect("/signin?error=signup_disabled");
  }
  
  return json({ signupAllowed });
}
```

## Security Features

### Authentication Security
- ✓ Secure session management with httpOnly cookies
- ✓ Password hashing with bcrypt
- ✓ Session expiration handling
- ✓ CSRF protection through Remix forms

### Authorization Security
- ✓ Role-based access control (RBAC)
- ✓ Route-level protection
- ✓ API endpoint authorization
- ✓ User status validation (active/inactive)

### Error Handling
- ✓ Graceful error responses
- ✓ Proper HTTP status codes
- ✓ Localized error messages (Arabic)
- ✓ Secure error information disclosure

## Testing

The route protection system includes comprehensive tests:

### Integration Tests
- Permission checking logic
- Auth level hierarchy validation
- Error response creation
- User status validation

### Route Tests
- Authentication requirement verification
- Role-based access control
- Redirection behavior
- Error handling

## Requirements Compliance

This implementation satisfies the following requirements:

### Requirement 6.1: User Authentication Levels
✓ Supports three auth levels: 1=superadmin, 2=admin, 3=user

### Requirement 6.2: Admin User Visibility
✓ Admins cannot see superadmin accounts
✓ Superadmins can see all user accounts

### Requirement 6.3: User Status Management
✓ Supports "active" and "inactive" status
✓ Inactive users are properly handled

### Requirement 6.4: Conditional Signup Access
✓ Signup restricted when admin users exist
✓ Signup allowed when no admin users exist

## Future Enhancements

Potential improvements for the route protection system:

1. **Rate Limiting**: Add rate limiting for authentication attempts
2. **Audit Logging**: Log access attempts and authorization failures
3. **Session Management**: Advanced session management with refresh tokens
4. **Multi-Factor Authentication**: Add MFA support for admin accounts
5. **API Key Authentication**: Support for API access with keys
6. **Permission Caching**: Cache permission checks for performance
7. **Dynamic Permissions**: Database-driven permission system

## Troubleshooting

### Common Issues

1. **Redirect Loops**: Check for circular redirects in auth logic
2. **Session Expiry**: Ensure proper session renewal
3. **Permission Denied**: Verify user auth level and status
4. **Inactive Users**: Check user status in database

### Debug Information

Enable debug logging by setting environment variables:
```bash
DEBUG=auth:*
LOG_LEVEL=debug
```

This will provide detailed information about authentication and authorization decisions.