/**
* {@inheritdoc}
*/
protected function prepareValue($delta, array &$values)
{
$date = FALSE;
$value = trim($values['value']);
if (is_numeric($value) || is_string($value) && ($value = strtotime($value))) {
$date = DrupalDateTime::createFromTimestamp($value, DATETIME_STORAGE_TIMEZONE);
} elseif ($value instanceof \DateTime) {
$date = DrupalDateTime::createFromDateTime($value);
}
if ($date && !$date->hasErrors()) {
$values['value'] = $date->format($this->storageFormat);
} else {
$values['value'] = '';
}
}
