<?php
header("content-type: text/plain");
$id = (int)($_GET["id"] ?? die(json_encode(["message" => "Unable to process request."])));

switch(file_exists($_SERVER["DOCUMENT_ROOT"] . "/asset/" . $id)){
    case true:
        $file = file_get_contents($_SERVER["DOCUMENT_ROOT"] . "/asset/" . $id);
        echo $file;
        break;
    default:
        header("Location: https://assetdelivery.roblox.com/v1/asset/?id=" . $id);
        die();
}
?>