hs_events.module

<?php

/**
 * @file
 * hs_events.mdoule
 */

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Entity\EntityInterface;
use Drupal\node\Entity\Node;
use Drupal\node\NodeForm;

/**
 * Implements hook_entity_delete().
 */
function hs_events_entity_delete(EntityInterface $entity) {
  if ($entity instanceof Node && $entity->bundle() == 'stanford_event') {
    $speakers = $entity->get('field_s_event_speaker')->getValue();
    foreach ($speakers as $speaker_value) {
      $speaker = \Drupal::entityTypeManager()
        ->getStorage('event_collections')
        ->load($speaker_value['target_id']);
      if ($speaker) {
        $speaker->delete();
      }
    }
  }
}

/**
 * Implements hook_field_widget_form_alter().
 */
function hs_events_field_widget_form_alter(&$element, FormStateInterface $form_state, $context) {
  // Make sure we have the node form.
  $callback_object = $form_state->getBuildInfo()['callback_object'];
  if (!$callback_object instanceof NodeForm) {
    return;
  }

  // Make sure we are on the stanford_event node form.
  $entity = $form_state->getBuildInfo()['callback_object']->getEntity();
  if (!($entity instanceof Node && $entity->bundle() == 'stanford_event')) {
    return;
  }

  /** @var \Drupal\Core\Field\WidgetBaseInterface $widget */
  $widget = $context['widget'];
  if ($widget->getBaseId() == 'daterange_datelist') {

    // Adds wrappers so we can easily find the parts with jQuery.
    $element['value']['#prefix'] = '<div class="start-date">';
    $element['value']['#suffix'] = '</div>';
    $element['end_value']['#prefix'] = '<div class="end-date">';
    $element['end_value']['#suffix'] = '</div>';

    $show_end = FALSE;

    // Compare start and end dates to determine default checkbox value.
    if (!empty($element['value']['#default_value']) && !empty($element['end_value']['#default_value'])) {
      /** @var \DateInterval $diff */
      $diff = $element['value']['#default_value']->diff($element['end_value']['#default_value']);
      $show_end = (bool) (int) $diff->format('%Y%M%D%H%I%S');
    }

    $element['show_end'] = [
      '#type' => 'checkbox',
      '#title' => t('Show End Date'),
      '#default_value' => $show_end,
      '#attributes' => ['class' => ['show-end-date']],
    ];

    $element['#attached']['library'][] = 'hs_events/admin';
    array_unshift($element['#element_validate'], 'hs_events_node_validate_date');
  }

}

/**
 * Implements hook_preprocess_select().
 */
function hs_events_preprocess_select(&$variables) {
  if (preg_match("/field_s_event_date.*?\[year\]/", $variables['element']['#name'])) {

    // Limit the number of years in the Event date field.
    $this_year = (int) date('Y');
    foreach ($variables['options'] as $key => $option) {
      if (!(int) $option['value']) {
        continue;
      }

      // Only show a 20 year span.
      $diff = abs($this_year - $option['value']);
      if ($diff > 10 && $option['value'] != $variables['element']['#value']) {
        unset($variables['options'][$key]);
      }
    }
  }
}

/**
 * Validation for event dates in nodes form.
 */
function hs_events_node_validate_date(array &$element, FormStateInterface $form_state) {

  $date = $form_state->getValue('field_s_event_date');

  // If the start value is populated but end is empty, copy the start date
  // to the end date to pass validation.
  if (!empty($date[0]['value']) && (!$date[0]['show_end'] || empty($date[0]['end_value']))) {
    $date[0]['end_value'] = $date[0]['value'];
    $element['end_value']['#value']['object'] = $date[0]['end_value'];

    /** @var \Drupal\Core\Datetime\DrupalDateTime $date */
    $form_state->setValue('field_s_event_date', $date);
  }
}