// extract picture information
$action = $_POST['action'];
$from = $_POST['from'];
$md5_id = $_POST['md5_id'];
$title = $_POST['title'];
$category = $_POST['category'];
$desc = $_POST['desc'];
if ($action != "update" && $action != "delete") {
    Util::log_and_die("Bad Request: unknown action: " . $action);
}
// file id check
if (!$md5_id) {
    Util::log_and_die("Bad Request: file's md5 id is missing");
}
// perform task depending on notification type
FileDB::init();
if ($action == "update") {
    $success = FileDB::update_record($md5_id, $title, $category, $desc);
    if (!$success) {
        Util::log_and_die("Server error: file info update failed");
    }
    Util::log_and_echo("Request processed: file info updated successfully");
} elseif ($action == "delete") {
    $file_path = FileDB::get_file_path($md5_id);
    $success = unlink($file_path);
    if (!$success) {
        Util::log_and_die("Server error: file deletion failed");
    }
    Util::log_and_echo("Request processed: file deleted successfully");
}
FileDB::close();