RegionalForm.php

<?php

namespace Drupal\system\Form;

use Drupal\Core\Config\ConfigFactoryInterface;
use Drupal\Core\Config\TypedConfigManagerInterface;
use Drupal\Core\Datetime\TimeZoneFormHelper;
use Drupal\Core\Form\ConfigTarget;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Form\RedundantEditableConfigNamesTrait;
use Drupal\Core\Locale\CountryManagerInterface;
use Drupal\Core\Form\ConfigFormBase;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Configure regional settings for this site.
 *
 * @internal
 */
class RegionalForm extends ConfigFormBase {
  use RedundantEditableConfigNamesTrait;
  
  /**
   * The country manager.
   *
   * @var \Drupal\Core\Locale\CountryManagerInterface
   */
  protected $countryManager;
  
  /**
   * Constructs a RegionalForm object.
   *
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The factory for configuration objects.
   * @param \Drupal\Core\Config\TypedConfigManagerInterface $typedConfigManager
   *   The typed config manager.
   * @param \Drupal\Core\Locale\CountryManagerInterface $country_manager
   *   The country manager.
   */
  public function __construct(ConfigFactoryInterface $config_factory, TypedConfigManagerInterface $typedConfigManager, CountryManagerInterface $country_manager) {
    parent::__construct($config_factory, $typedConfigManager);
    $this->countryManager = $country_manager;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container->get('config.factory'), $container->get('config.typed'), $container->get('country_manager'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'system_regional_settings';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $countries = $this->countryManager
      ->getList();
    // Date settings:
    $zones = TimeZoneFormHelper::getOptionsListByRegion();
    $form['locale'] = [
      '#type' => 'details',
      '#title' => $this->t('Locale'),
      '#open' => TRUE,
    ];
    $form['locale']['site_default_country'] = [
      '#type' => 'select',
      '#title' => $this->t('Default country'),
      '#empty_value' => '',
      '#config_target' => new ConfigTarget('system.date', 'country.default', toConfig: fn(?string $value) => $value ?: NULL),
      '#options' => $countries,
      '#attributes' => [
        'class' => [
          'country-detect',
        ],
      ],
    ];
    $form['locale']['date_first_day'] = [
      '#type' => 'select',
      '#title' => $this->t('First day of week'),
      '#config_target' => 'system.date:first_day',
      '#options' => [
        0 => $this->t('Sunday'),
        1 => $this->t('Monday'),
        2 => $this->t('Tuesday'),
        3 => $this->t('Wednesday'),
        4 => $this->t('Thursday'),
        5 => $this->t('Friday'),
        6 => $this->t('Saturday'),
      ],
    ];
    $form['timezone'] = [
      '#type' => 'details',
      '#title' => $this->t('Time zones'),
      '#open' => TRUE,
    ];
    $form['timezone']['date_default_timezone'] = [
      '#type' => 'select',
      '#title' => $this->t('Default time zone'),
      '#config_target' => new ConfigTarget('system.date', 'timezone.default', static::class . '::loadDefaultTimeZone'),
      '#options' => $zones,
    ];
    return parent::buildForm($form, $form_state);
  }
  
  /**
   * Prepares the saved timezone.default property to be displayed in the form.
   *
   * @param string|null $value
   *   The value saved in config.
   *
   * @return string
   *   The value of the form element.
   */
  public static function loadDefaultTimeZone(?string $value) : string {
    return $value ?: date_default_timezone_get();
  }

}