Get Roblox assets in PHP, can be used as passthrough function

asset.php

<?php
	function parse_response_headers($headers)
    {
        $head = [];
        foreach ($headers as $key => $value)
        {
            $type = explode(":", $value, 2);

            if (isset($type[1]))
            {
                $head[trim($type[0])] = trim($type[1]);
            }
            else
            {
                $head[] = $value;
                if (preg_match("#HTTP/[0-9\.]+\s+([0-9]+)#", $value, $out))
                {
                    $head["reponse_code"] = intval($out[1]);
                }
            }
        }

        return $head;
    }
	
	if (!isset($_GET["id"]) || strlen($_GET["id"]) <= 0 || !is_int((int)$_GET["id"])) // I use strlen instead of empty because empty returns "false" if it's "falsey", e.g asset id "0"
    {
        http_response_code(404);
        exit();
    }
	
    $id = filter_var($_GET["id"], FILTER_SANITIZE_NUMBER_INT, FILTER_NULL_ON_FAILURE);
    $version = isset($_GET["version"]) ? filter_var($_GET["version"], FILTER_SANITIZE_NUMBER_INT, FILTER_NULL_ON_FAILURE) : -1; // -1 is the latest version internally.
    
    if (!isset($id) || empty($id) || $id == NULL)
    {
        // We at least need an asset id
        http_response_code(404);
        exit();
    }
	
	$url = "https://assetdelivery.roblox.com/v1/assetId/$id";
	if ($version != -1 || $version != NULL) // Get specific version
	{
		$url .= "/version/$version";
	}
	
	$options = ["http" => ["user_agent" => "Roblox"]]; // Set user agent because of KTX
	$context = stream_context_create($options);
	$asset = @file_get_contents($url, false, $context);

	if ($asset)
	{
		$asset = json_decode($asset, true);
		if (isset($asset["errors"]))
		{
			if ((int)$asset["errors"][0]["code"] == 0)
			{
				// We messed up something
				http_response_code(400);
				exit();
			}

			http_response_code((int)$asset["errors"][0]["code"]); // handles 404, 409, etc.
			exit();
		}

		// Required for conflict between "Location" and "location"
		foreach ($asset as $key => $value)
		{
			$asset[trim(strtolower($key))] = trim($value);
		}

		// Deliver Roblox asset
		$file = file_get_contents($asset["location"]);
		$headers = parse_response_headers($http_response_header); // $http_response_header materializes out of thin air. parse_response_headers is our own function
		
		header("Content-Length: " . $headers["Content-Length"]);
		header("Content-Type: " . $headers["Content-Type"]);
		exit($file); // Return it
	}
	else
	{
		// Internal error
		http_response_code(400);
		exit();
	}  
    
    // We fell through literally everything. This shouldn't ever happen, but if this is the case, then lets not leave holes open
    http_response_code(404);
    exit();
?>