Relations between case type and actor types done

src/EntityTypeRelations.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Drupal\opencase;
+
+/**
+ * Stuff to do with the relationship of case types to actor types, and activity types to case types
+ *
+ */
+class EntityTypeRelations {
+
+
+  public static function getAllowedParentBundles($childEntityType, $childBundle) {
+    $field = $childEntityType == 'oc_case' ? 'actors_involved' : 'oc_case';
+    $base_field_override = \Drupal\Core\Field\Entity\BaseFieldOverride::load("$childEntityType.$childBundle.$field");
+    $allowedBundles = array();
+    if ($base_field_override) { 
+      $actor_types =  $base_field_override->getSettings()['handler_settings']['target_bundles'];
+      // example of the $actor_types array: ['client' => 'client', 'volunteer' => 0]
+      foreach($actor_types as $machine_name => $value) {
+        if ($value) {
+          $allowedBundles[] = $machine_name;        
+        }
+      }
+    }
+    return $allowedBundles; // NB. this is an array of machine names only, indexed numerically.
+  }
+
+  public static function getAllowedChildBundles($parentEntityType, $parentBundle) {
+    $childEntityType = $parentEntityType == 'oc_case' ? 'oc_activity' : 'oc_case';
+    // get all the child bundles
+    $childBundles = \Drupal::service('entity_type.bundle.info')->getBundleInfo($childEntityType);
+    // $childBundles is array where the key is the machine name and the value is array containing label
+    $allowedChildBundles = array();
+    foreach(array_keys($childBundles) as $childBundle) {
+      if (in_array($parentBundle, self::getAllowedParentBundles($childEntityType, $childBundle))) {
+        $allowedChildBundles[$childBundle] = $childBundles[$childBundle]['label'];
+      }
+    }
+    return $allowedChildBundles; // NB. this is an array of labels, indexed by machine name.
+    
+  }
+}