public function buildSortFields($fields)
{
$sortFields = [];
foreach ((array) $fields as $key => $value) {
if (is_int($key)) {
$sortFields[$value] = +1;
} else {
if ($value === SORT_ASC) {
$value = +1;
} elseif ($value === SORT_DESC) {
$value = -1;
}
$sortFields[$key] = $value;
}
}
return $sortFields;
}