Azure Web PubSub negotiate via PHP

PubSubToken.php

<?php
declare(strict_types=1);

class PubSubToken {
    protected $endpoint;
    protected $wssEndpoint;
    protected $accesskey;
    protected $version;
    protected $alg = 'HS256';

    public function __construct($connectionString)
    {
        $params = explode(';', $connectionString);
        foreach ($params as $param) {
            list($k, $v) = explode('=', $param, 2);

            $this->{strtolower($k)} = $v;
        }

        $this->wssEndpoint = preg_replace('/(http)(s?:\/\/)/i', 'ws$2', $this->endpoint);

        if ($this->endpoint === null || $this->accesskey === null || $this->version === null || $this->wssEndpoint === null) {
            throw new \Exception('Parameter error');            
        }
    }

    public function getAuthenticationToken(string $hub, string $userId = null, int $ttl = 3600): array
    {
        $now = time();

        $payload = [
            'iat' => $now,
            'exp' => $now + $ttl,
            'aud' => "{$this->endpoint}/client/hubs/{$hub}",
        ];
        if ($userId !== null) {
            $payload['sub'] = $userId;
        }

        $jwt = new \JOSE_JWT($payload);
        $jwt->header['alg'] = $this->alg;
        $jwt->header['typ'] = 'JWT';
        $jwt->sign($this->accesskey, $this->alg);
        
        $jws = new \JOSE_JWS($jwt);
        $jws = $jws->sign($this->accesskey, $this->alg);
        $token = $jws->toString();
        
        return [
            'baseUrl' => "{$this->wssEndpoint}/client/hubs/{$hub}",
            'token' => $token,
            'url' => "{$this->wssEndpoint}/client/hubs/{$hub}?access_token={$token}",
        ];
    }
}

test.php

<?php

$connectionString = 'Your Azure Web PubSub connection string';

$pubsub = new PubSubToken($connectionString);
$token = $pubsub->getAuthenticationToken('test');
var_dump($token);