openvk/Web/Presenters/ActivityPubPresenter.php

<?php declare(strict_types=1);
namespace openvk\Web\Presenters;
use openvk\Web\Models\Repositories\Users;

final class ActivityPubPresenter extends OpenVKPresenter
{    
    function renderWellKnown(): void
    {
        if ($_SERVER['REQUEST_URI'] == "/.well-known/host-meta") {
            $data = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
            . "<XRD xmlns=\"http://docs.oasis-open.org/ns/xri/xrd-1.0\">\n"
            . "  <Link rel=\"lrdd\" template=\"" . ovk_scheme(true) . $_SERVER["SERVER_NAME"] . "/.well-known/webfinger?resource={uri}\">\n"
            . "</XRD>\n";

            header("Content-Type: application/xrd+xml; charset=utf-8");
            exit($data);
        } else if ($this->startsWith($_SERVER["REQUEST_URI"], '/.well-known/webfinger') && $this->startsWith($this->requestParam("resource"), 'acct:')) {
            $username = array();
            $subject = substr($this->requestParam("resource"), 5, strlen($this->requestParam("resource")));
            preg_match('/([a-zA-Z0-9-_]+)@([a-zA-Z0-9-_\.]+)/', $subject, $username);
            $username = $username[1];

            $user = (new Users)->getByShortURL($username);

            if($user !== null) {
                $response->subject = $this->requestParam("resource");
                
                $response->links[] = array(
                    'rel' => 'self',
                    'href' => ovk_scheme(true) . $_SERVER["SERVER_NAME"] . '/id' . $user->getId(),
                    'type' => 'application/activity+json'
                );

                header("Access-Control-Allow-Origin: *");
                $this->returnJson((array) $response);
            } else {
                header("HTTP/2 404 Not Found");
                exit();
            };
        } else {
            header("HTTP/2 404 Not Found");
            exit();
        }
    }

    private function startsWith($string, $startString)
    {
        $len = strlen($startString);
        return (substr($string, 0, $len) === $startString);
    }
}