Nemotron 3 Ultra (free)

<?php

namespace Drupal\date_block\Plugin\Block;

use Drupal\Core\Block\Attribute\Block;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Datetime\DateFormatterInterface;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Provides a 'Current Date' block.
 */
#[Block(
  id: "date_block",
  admin_label: new TranslatableMarkup("Current Date"),
  category: new TranslatableMarkup("Custom")
)]
class DateBlock extends BlockBase implements ContainerFactoryPluginInterface {

  /**
   * The date formatter service.
   *
   * @var \Drupal\Core\Datetime\DateFormatterInterface
   */
  protected $dateFormatter;

  /**
   * Constructs a DateBlock object.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin ID for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\Core\Datetime\DateFormatterInterface $date_formatter
   *   The date formatter service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, DateFormatterInterface $date_formatter) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->dateFormatter = $date_formatter;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static(
      $configuration,
      $plugin_id,
      $plugin_definition,
      $container->get('date.formatter')
    );
  }

  /**
   * {@inheritdoc}
   */
  public function defaultConfiguration() {
    return [
      'date_format' => 'short',
      'custom_date_format' => '',
      'label_display' => TRUE,
    ] + parent::defaultConfiguration();
  }

  /**
   * {@inheritdoc}
   */
  public function blockForm($form, FormStateInterface $form_state) {
    $formats = $this->dateFormatter->getAllFormats();

    $form['date_format'] = [
      '#type' => 'select',
      '#title' => $this->t('Date format'),
      '#description' => $this->t('Select the date format to use for displaying the current date.'),
      '#default_value' => $this->configuration['date_format'],
      '#options' => $formats,
      '#empty_option' => $this->t('- Custom -'),
      '#empty_value' => 'custom',
    ];

    $form['custom_date_format'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Custom date format'),
      '#description' => $this->t('Enter a custom PHP date format string. See <a href=":url" target="_blank">PHP date() function</a> for format options.', [':url' => 'https://www.php.net/manual/en/function.date.php']),
      '#default_value' => $this->configuration['custom_date_format'],
      '#states' => [
        'visible' => [
          ':input[name="date_format"]' => ['value' => 'custom'],
        ],
      ],
    ];

    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function blockSubmit($form, FormStateInterface $form_state) {
    $this->configuration['date_format'] = $form_state->getValue('date_format');
    $this->configuration['custom_date_format'] = $form_state->getValue('custom_date_format');
  }

  /**
   * {@inheritdoc}
   */
  public function build() {
    $current_time = \Drupal::time()->getRequestTime();

    if ($this->configuration['date_format'] === 'custom' && !empty($this->configuration['custom_date_format'])) {
      $date_string = $this->dateFormatter->format($current_time, 'custom', $this->configuration['custom_date_format']);
    }
    else {
      $date_string = $this->dateFormatter->format($current_time, $this->configuration['date_format']);
    }

    return [
      '#markup' => $date_string,
      '#cache' => [
        'max-age' => 0,
      ],
    ];
  }

}