opencase/modules/opencase_cases/opencase_cases.module

<?php

/**
 * @file
 * Contains opencase_cases.module.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function opencase_cases_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the opencase_cases module.
    case 'help.page.opencase_cases':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Provides case entities and a required field on activities linking them to a case.') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_theme().
 */
function opencase_cases_theme() {
  return [
    'opencase_cases' => [
      'render element' => 'children',
    ],
    'oc_case' => [
      'render element' => 'elements',
      'file' => 'oc_case.page.inc',
      'template' => 'oc_case',
    ],
    'oc_case_content_add_list' => [
      'render element' => 'content',
      'variables' => ['content' => NULL],
      'file' => 'oc_case.page.inc',
    ],
    'oc_actor_case_relation' => [
      'render element' => 'elements',
      'file' => 'oc_actor_case_relation.page.inc',
      'template' => 'oc_actor_case_relation',
    ],
    'oc_actor_case_relation_content_add_list' => [
      'render element' => 'content',
      'variables' => ['content' => NULL],
      'file' => 'oc_actor_case_relation.page.inc',
    ]
  ];
}

function opencase_cases_entity_base_field_info($entity_type) {
  $fields = array();
  
  // Add Case field to Activity 
  if ($entity_type->id() === 'oc_activity') {
    $fields['oc_case'] = \Drupal\Core\Field\BaseFieldDefinition::create('entity_reference')
      ->setLabel(t('Case'))
      ->setDescription(t('The case this activity belongs to.'))
      ->setSetting('target_type', 'oc_case')
      ->setSetting('handler', 'default')
      ->setTranslatable(TRUE)
      ->setCardinality(1)
      ->setDefaultValueCallback('opencase_cases_default_activity_case_value')
      ->setDisplayOptions('view', [
        'type' => 'string',
        'weight' => -3,
      ])
      ->setRequired(TRUE);
  }
  return $fields;
}

/**
 * When creating an activity, it sets the case id from the URL.
 */
function opencase_cases_default_activity_case_value() {
  return array(\Drupal::request()->query->get('case_id'));
}

/**
 * Implementation of hook_form_alter()
 * Changes what page is redirected to after deleting things
 */
function opencase_cases_form_alter(&$form, &$form_state, $form_id) {
  if (preg_match('/oc_actor_.*_delete_form/', $form_id) or (preg_match('/oc_case_.*_delete_form/', $form_id)) or (preg_match('/oc_organisation_.*_delete_form/', $form_id))) {
    $form['actions']['submit']['#submit'][] = '_opencase_cases_redirect_to_home';
    $form['actions']['cancel']['#url'] = $form_state->getFormObject()->getEntity()->toUrl();
  }
  if (preg_match('/oc_activity_.*_delete_form/', $form_id)) {
    $form['actions']['submit']['#submit'][] = '_opencase_cases_delete_activity_redirect';
    $form['actions']['cancel']['#url'] = $form_state->getFormObject()->getEntity()->toUrl();
  }
}

function _opencase_cases_redirect_to_home($form, &$form_state) {
  $form_state->setRedirect('<front>'); 
}
function _opencase_cases_delete_activity_redirect($form, &$form_state) {
  $case_id = $form_state->getFormObject()->getEntity()->oc_case->target_id;
  $form_state->setRedirect('entity.oc_case.canonical', ['oc_case' => $case_id]);
}
/**
* Implements hook_theme_suggestions_HOOK().
*/
function opencase_cases_theme_suggestions_oc_case(array $variables) {
  $suggestions = [];
  $entity = $variables['elements']['#oc_case'];
  $sanitized_view_mode = strtr($variables['elements']['#view_mode'], '.', '_');

  $suggestions[] = 'oc_case__' . $sanitized_view_mode;
  $suggestions[] = 'oc_case__' . $entity->bundle();
  $suggestions[] = 'oc_case__' . $entity->bundle() . '__' . $sanitized_view_mode;
  $suggestions[] = 'oc_case__' . $entity->id();
  $suggestions[] = 'oc_case__' . $entity->id() . '__' . $sanitized_view_mode;
  return $suggestions;
}

function opencase_views_query_alter(Drupal\views\ViewExecutable $view, $query) {
  if ($view->getBaseEntityType() && $view->getBaseEntityType()->id() == 'oc_case') {
    $query->addTag('oc_case_access');
  }
  if ($view->getBaseEntityType() && $view->getBaseEntityType()->id() == 'oc_activity') {
    $query->addTag('oc_activity_access');
  }
}

function opencase_query_oc_case_access_alter($query) {
  if (\Drupal::currentUser()->hasPermission('view published case entities')) {
    return;
  } 
  $linked_actor_id = CaseInvolvement::getLinkedActorId(\Drupal::currentUser());
  $query->addJoin('INNER', 'oc_case__actors_involved', 'access_filter', 'access_filter.entity_id = oc_case_field_data.id');
  $query->condition('access_filter.actors_involved_target_id', $linked_actor_id);
}

function opencase_query_oc_activity_access_alter($query) {
  if (\Drupal::currentUser()->hasPermission('view published case entities')) {
    return;
  } 
  $linked_actor_id = CaseInvolvement::getLinkedActorId(\Drupal::currentUser());
  $query->addJoin('INNER', 'oc_case__actors_involved', 'access_filter', 'access_filter.entity_id = oc_activity_field_data.oc_case');
  $query->condition('access_filter.actors_involved_target_id', $linked_actor_id);
}

/**
 * Implements hook_theme_suggestions_HOOK().
 */
function opencase_cases_theme_suggestions_oc_actor_case_relation(array $variables) {
  $suggestions = [];
  $entity = $variables['elements']['#oc_actor_case_relation'];
  $sanitized_view_mode = strtr($variables['elements']['#view_mode'], '.', '_');

  $suggestions[] = 'oc_actor_case_relation__' . $sanitized_view_mode;
  $suggestions[] = 'oc_actor_case_relation__' . $entity->bundle();
  $suggestions[] = 'oc_actor_case_relation__' . $entity->bundle() . '__' . $sanitized_view_mode;
  $suggestions[] = 'oc_actor_case_relation__' . $entity->id();
  $suggestions[] = 'oc_actor_case_relation__' . $entity->id() . '__' . $sanitized_view_mode;
  return $suggestions;
}