Form Builder & Validation Demo

<?php
namespace App\Shared\Forms;

use App\Shared\Forms\Fields\InputField;
use App\Shared\Forms\Fields\TextareaField;
use App\Shared\Forms\Fields\SelectField;
use App\Shared\Validation\ValidationBag;

class Form
{
    protected string $action = '';
    protected string $method = 'POST';
    protected array $fields = [];
    protected array $attributes = [];
    protected ?ValidationBag $errors = null;
    protected ?array $oldInput = null;
    protected bool $csrfProtection = true;

    /**
     * Create new form instance
     */
    public static function create(): static
    {
        return new static();
    }

    /**
     * Set form action URL
     */
    public function action(string $action): static
    {
        $this->action = $action;
        return $this;
    }

    /**
     * Set form method
     */
    public function method(string $method): static
    {
        $this->method = strtoupper($method);
        return $this;
    }

    /**
     * Add text input field
     */
    public function text(string $name): InputField
    {
        $field = new InputField($name);
        $field->type('text');
        
        if ($this->errors) {
            $field->errors($this->errors);
        }
        
        if ($this->oldInput) {
            $field->oldInput($this->oldInput);
        }
        
        $this->fields[] = $field;
        return $field;
    }

    /**
     * Add email input field
     */
    public function email(string $name): InputField
    {
        $field = new InputField($name);
        $field->type('email');
        
        if ($this->errors) {
            $field->errors($this->errors);
        }
        
        $this->fields[] = $field;
        return $field;
    }

    /**
     * Add textarea field
     */
    public function textarea(string $name): TextareaField
    {
        $field = new TextareaField($name);
        
        if ($this->errors) {
            $field->errors($this->errors);
        }
        
        $this->fields[] = $field;
        return $field;
    }

    /**
     * Render complete form
     */
    public function render(): string
    {
        $html = $this->getOpeningTag();
        
        // Add CSRF token
        if ($this->csrfProtection) {
            $html .= $this->getCsrfField();
        }
        
        // Render all fields
        foreach ($this->fields as $field) {
            $html .= $field->render();
        }
        
        $html .= '';
        
        return $html;
    }
}

<?php
namespace App\Frontend\Controllers;

use App\Backend\Core\BaseController;
use App\Shared\Forms\Form;
use App\Shared\Validation\Validator;

class FormController extends BaseController
{
    public function contact()
    {
        // Create form using our Form Builder
        $form = Form::create()
            ->action(route('demo.forms.contact'))
            ->method('POST')
            ->class('contact-form');

        // Add form fields with validation rules
        $form->text('name')
            ->label('Full Name')
            ->placeholder('Enter your name')
            ->required()
            ->rules(['required', 'min:2', 'max:50']);

        $form->email('email')
            ->label('Email Address')
            ->placeholder('example@domain.com')
            ->required()
            ->rules(['required', 'email']);

        $form->textarea('message')
            ->label('Message')
            ->placeholder('Write your message')
            ->attributes(['rows' => 5])
            ->required()
            ->rules(['required', 'min:10', 'max:500']);

        $form->submit('Submit Message', ['class' => 'btn btn-primary']);

        return $this->view->render('demo/forms', [
            'title' => 'Forms & Validation Demo',
            'form' => $form,
            'validation_rules' => $this->getValidationRules()
        ]);
    }

    public function processContact()
    {
        $data = $this->request->getParsedBody();
        
        // Define validation rules
        $rules = [
            'name' => 'required|min:2|max:50',
            'email' => 'required|email',
            'message' => 'required|min:10|max:500'
        ];
        
        // Validate data using our Validator
        $validator = Validator::make($data, $rules);
        
        if ($validator->fails()) {
            // Return with errors
            return $this->response->json([
                'success' => false,
                'errors' => $validator->errors()->toArray()
            ], 422);
        }
        
        $validatedData = $validator->validated();
        
        // Process the form (send email, save to database, etc.)
        $this->sendContactEmail($validatedData);
        
        return $this->response->json([
            'success' => true,
            'message' => 'Message sent successfully!'
        ]);
    }
}

<?php
use App\Shared\Forms\Form;

$form = Form::create();

// Text input with validation
$form->text('username')
    ->label('Username')
    ->placeholder('username123')
    ->maxLength(30)
    ->required()
    ->rules(['required', 'min:3', 'max:30', 'alpha_dash']);

// Email input
$form->email('email')
    ->label('Email Address')
    ->required()
    ->rules(['required', 'email']);

// Password input
$form->password('password')
    ->label('Password')
    ->required()
    ->rules(['required', 'min:8']);

// Number input with min/max
$form->number('age')
    ->label('Age')
    ->min(18)
    ->max(100)
    ->rules(['required', 'numeric', 'min:18', 'max:100']);

// File upload
$form->file('avatar')
    ->label('Profile Picture')
    ->accept('image/*')
    ->rules(['file', 'image', 'max:2048']); // Max 2MB

// Textarea
$form->textarea('bio')
    ->label('About You')
    ->rows(4)
    ->maxLength(500)
    ->rules(['max:500']);

// Select dropdown
$form->select('country')
    ->label('Country')
    ->options([
        'tr' => 'Turkey',
        'us' => 'United States',
        'uk' => 'United Kingdom'
    ])
    ->emptyOption('Select Country...')
    ->required()
    ->rules(['required']);

// Checkbox
$form->checkbox('terms')
    ->label('I agree to terms and conditions')
    ->required()
    ->rules(['accepted']);

// Submit button
$form->submit('Create Account', [
    'class' => 'btn btn-primary btn-lg'
]);

<?php
// CSRF token generation in Form class
protected function getCsrfField(): string
{
    $token = $this->generateCsrfToken();
    return '<input type="hidden" name="csrf_token" value="' . $token . '">';
}

private function generateCsrfToken(): string
{
    if (!isset($_SESSION['csrf_token'])) {
        $_SESSION['csrf_token'] = bin2hex(random_bytes(32));
    }
    return $_SESSION['csrf_token'];
}

// CSRF validation in request processing
public function validateCsrfToken(array $data): bool
{
    $token = $data['csrf_token'] ?? '';
    $sessionToken = $_SESSION['csrf_token'] ?? '';
    
    if (!hash_equals($sessionToken, $token)) {
        throw new SecurityException('CSRF token mismatch');
    }
    
    return true;
}

<?php
namespace App\Shared\Validation;

class Validator
{
    public static function make(array $data, array $rules): static
    {
        $validator = new static();
        $validator->data = $data;
        $validator->rules = $rules;
        $validator->errors = new ValidationBag();
        
        $validator->validate();
        
        return $validator;
    }

    private function validateRequired(string $field, $value): bool
    {
        if (empty($value)) {
            $this->errors->add($field, "The {$field} field is required.");
            return false;
        }
        return true;
    }

    private function validateEmail(string $field, $value): bool
    {
        if (!empty($value) && !filter_var($value, FILTER_VALIDATE_EMAIL)) {
            $this->errors->add($field, "The {$field} must be a valid email address.");
            return false;
        }
        return true;
    }
}