crm_core-8.x-3.x-dev/modules/crm_core_activity/crm_core_activity.module

<?php

/**
 * @file
 * Provides an entity for recording a contact's activities.
 */

use Drupal\Core\Entity\EntityInterface;

/**
 * Implements hook_entity_predelete() for CRM Core Contact entities.
 */
function crm_core_activity_entity_predelete(EntityInterface $entity) {
  switch ($entity->getEntityTypeId()) {
    case 'crm_core_individual':
      crm_core_activity_pre_delete_checker($entity);
      break;

    case 'crm_core_organization':
      crm_core_activity_pre_delete_checker($entity);
      break;
  }
}

/**
 * Looks for activities to be removed.
 *
 * Separate function for running for both Individual and Organization.
 * If current entity to be deleted was only participant in Activity, that
 * activity will be removed.
 *
 * @param Drupal\Core\Entity\EntityInterface $entity
 *   The entity ID to be looked for from participants.
 */
function crm_core_activity_pre_delete_checker(EntityInterface $entity) {
  $activities_to_remove = [];
  $entity_id = $entity->id();
  $entity_type = $entity->getEntityTypeId();
  $activity_storage = \Drupal::entityTypeManager()->getStorage('crm_core_activity');

  $query = \Drupal::entityQuery('crm_core_activity');
  $activity_ids = $query
    ->condition('activity_participants.target_id', $entity_id)
    ->condition('activity_participants.target_type', $entity_type)
    ->accessCheck(TRUE)
    ->execute();
  if (empty($activity_ids)) {
    // No related Activities.
    return;
  }
  // Load fully populated Activity objects to analyze/update.
  $crm_core_activities = $activity_storage->loadMultiple($activity_ids);

  foreach ($crm_core_activities as $crm_core_activity) {
    /** @var \Drupal\crm_core_activity\Entity\Activity $crm_core_activity */
    $participants = $crm_core_activity->get('activity_participants')->getValue();
    // Remove Individual from participants array.
    $participants = array_diff(array_column($participants, 'target_id'), [$entity_id]);
    if (empty($participants)) {
      // Last main participant was deleted, so we should kill entire activity.
      $activities_to_remove[] = $crm_core_activity->id();
    }
    else {
      // Save Activity with renewed list.
      $crm_core_activity->set('activity_participants', $participants);
      $crm_core_activity->save();
    }
  }

  if (!empty($activities_to_remove)) {
    $activities = $activity_storage->loadMultiple($activities_to_remove);
    \Drupal::logger('crm_core_activity')->info('Deleted @count activities due to deleting @type id=%individual_id.', [
      '@count' => count($activities_to_remove),
      '@type' => $entity_type,
      '%individual_id' => $entity_id,
    ]);
    $activity_storage->delete($activities);
  }
}