<?php

namespace Drupal\sd8;

use Drupal\Core\Entity\ContentEntityInterface;
use Drupal\Core\Field\EntityReferenceFieldItemListInterface;

/**
 * Convert an entity to an array and back.
 */
class EntityArrayHelper {

  /**
   * Convert an array to entity or entities.
   *
   * @param $entityTypeId
   *   The entity type id.
   * @param array $data
   *   Similar to what can be passed ContentEntityStorageInterface::create()
   *   but entity references can be inlined and they will be autocreated. The
   *   reference entity type can be specified by an entity_type key.
   *   Run static::entity2array() for examples.
   *
   * @return \Drupal\Core\Entity\ContentEntityInterface
   */
  public static function array2entity($entityTypeId, array $data) {
    /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
    $entity = \Drupal::entityTypeManager()->getStorage($entityTypeId)->create($data);
    foreach ($entity->getFieldDefinitions() as $fieldName => $fieldDefinition) {
      $fieldItemList = $entity->get($fieldName);
      if (isset($data[$fieldName]) && $fieldItemList instanceof EntityReferenceFieldItemListInterface) {
        if (!isset($data[$fieldName][0])) {
          $data[$fieldName] = [$data[$fieldName]];
        }
        foreach ($data[$fieldName] as $referencedData) {
          if (!isset($referencedData['target_id'])) {
            $referencedEntityTypeId = $referencedData['entity_type'] ?? $fieldDefinition->getSetting('target_type');
            $fieldItemList->appendItem(static::array2entity($referencedEntityTypeId, $referencedData));
          }
        }
      }
    }
    return $entity;
  }

  /**
   * Convert an entity to an array, inlining referred entities.
   *
   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
   *   Entity to be converted.
   * @param array $inline
   *   Entity type IDs to be inlined.
   *
   * @return array
   *   Similar to $entity->toArray() but the values for entity references are
   *   not target_id but the entire referenced $entity->toArray() for types in
   *   $expand. As the default value of $inline shows, this is very useful for
   *   paragraphs.
   */
  public static function entity2array(ContentEntityInterface $entity, array $inline = ['paragraph']) {
    $array = $entity->toArray();
    foreach ($entity->getFields() as $fieldName => $fieldItemList) {
      if ($fieldItemList instanceof EntityReferenceFieldItemListInterface) {
        foreach ($fieldItemList->referencedEntities() as $delta => $referencedEntity) {
          if ($referencedEntity instanceof ContentEntityInterface && array_search($referencedEntity->getEntityTypeId(), $inline) !== FALSE) {
            $array[$fieldName][$delta] = static::inlineEntity($referencedEntity, $inline);
          }
        }
      }
    }
    return $array;
  }

  /**
   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
   *
   * @param array $inline
   *
   * @return array
   */
  protected static function inlineEntity(ContentEntityInterface $entity, array $inline) {
    $array = static::entity2array($entity, $inline);
    $array['entity_type'] = $entity->getEntityTypeId();
    $keys = $entity->getEntityType()->getKeys();
    unset($array[$keys['id']], $array[$keys['revision']], $array[$keys['uuid']]);
    return $array;
  }

}