trait EntityChangedFieldsTrait in Brightcove Video Connect 3.x

trait EntityChangedFieldsTrait {

  /**
   * Changed fields.
   *
   * @var bool[]
   */
  protected $changedFields;

  /**
   * Has changed field or not.
   *
   * @var bool
   */
  protected $hasChangedField = FALSE;

  /**
   * Returns whether the field is changed or not.
   *
   * @param string $name
   *   The name of the field on the entity.
   *
   * @return bool
   *   The changed status of the field, TRUE if changed, FALSE otherwise.
   */
  public function isFieldChanged($name) {

    // Indicate that there is at least one changed field.
    if (!$this->changedFields) {
      $this->changedFields = TRUE;
    }
    return !empty($this->changedFields[$name]);
  }

  /**
   * Checked if the Entity has a changed field or not.
   *
   * @return bool
   *   TRUE if if the entity has changed fields, FALSE otherwise.
   */
  public function hasChangedField() {
    return $this->hasChangedField;
  }

  /**
   * Check for updated fields.
   *
   * Ideally it should be called from the entity's preSave() method before the
   * parent's preSave() call.
   *
   * @param \Drupal\Core\Entity\EntityStorageInterface $storage
   *   Entity storage.
   */
  public function checkUpdatedFields(EntityStorageInterface $storage) {

    // Collect object getters.
    $methods = [];
    foreach (get_class_methods($this) as $key => $method) {

      // Create a matchable key for the get methods.
      if (preg_match('/^(?:get|is)[\\w\\d_]+$/i', $method)) {
        $methods[strtolower($method)] = $method;
      }
    }

    // Check fields if they were updated and mark them if changed.
    if (!empty($this
      ->id())) {

      /** @var \Drupal\brightcove\Entity\BrightcoveVideo $original_entity */
      $original_entity = $storage
        ->loadUnchanged($this
        ->id());
      if ($original_entity
        ->getChangedTime() != $this
        ->getChangedTime()) {

        /** @var \Drupal\Core\Field\FieldItemList $field */
        foreach ($this
          ->getFields() as $name => $field) {
          $getter = $this
            ->getGetterName($name, $methods);

          // If the getter is available for the field then compare the two
          // field and if changed mark it.
          if (!is_null($getter) && $this
            ->{$getter}() != $original_entity
            ->{$getter}()) {
            $this->changedFields[$name] = TRUE;
          }
        }
      }
    }
    else {
      foreach ($this
        ->getFields() as $name => $field) {
        if (!is_null($this
          ->getGetterName($name, $methods))) {
          $this->changedFields[$name] = TRUE;
        }
      }
    }
  }

  /**
   * Get getter method from the name of the field.
   *
   * @param string $name
   *   The name of the field.
   * @param array $methods
   *   The available methods.
   *
   * @return string
   *   The name of the getter function.
   */
  public function getGetterName($name, array $methods) {
    $function_part_name = $name;

    // Get entity key's status field alias.
    $status = self::getEntityType()
      ->getKey('status');

    // Use the correct function for the status field.
    if ($name == $status) {
      $function_part_name = 'published';
    }

    // Acquire getter method name.
    $getter_name = 'get' . str_replace('_', '', $function_part_name);
    $is_getter_name = 'is' . str_replace('_', '', $function_part_name);
    $getter = NULL;
    if (isset($methods[$getter_name])) {
      $getter = $methods[$getter_name];
    }
    elseif (isset($methods[$is_getter_name])) {
      $getter = $methods[$is_getter_name];
    }
    return $getter;
  }

}