SwitchUserPageForm.php

<?php

namespace Drupal\devel\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormBuilderInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\devel\SwitchUserListHelper;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Define an accessible form to switch the user.
 */
class SwitchUserPageForm extends FormBase {
    
    /**
     * The FormBuilder object.
     */
    protected FormBuilderInterface $formBuilder;
    
    /**
     * A helper for creating the user list form.
     */
    protected SwitchUserListHelper $switchUserListHelper;
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) : static {
        $instance = parent::create($container);
        $instance->switchUserListHelper = $container->get('devel.switch_user_list_helper');
        $instance->formBuilder = $container->get('form_builder');
        return $instance;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() : string {
        return 'devel_switchuser_page_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) : array {
        if ($accounts = $this->switchUserListHelper
            ->getUsers()) {
            $form['devel_links'] = $this->switchUserListHelper
                ->buildUserList($accounts);
            $form['devel_form'] = $this->formBuilder
                ->getForm(SwitchUserForm::class);
        }
        else {
            $this->messenger
                ->addStatus('There are no user accounts present!');
        }
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) : void {
        // Nothing to do here. This is delegated to devel.switch via http call.
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) : void {
        // Nothing to do here. This is delegated to devel.switch via http call.
    }

}