upload file, only PDF type, give random file name

function getFileName($file, $file_type){
    $file_type = strtolower($file_type);
    if($file_type == "pdf"){
        $file_name = "../uploads/" . time() . "-" . basename($file["name"]);
        if(move_uploaded_file($file["tmp_name"], $file_name)){
            return $file_name;
        }
    }
    return false;
}

$file_type = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));
$target_file = getFileName($file, $file_type);