/**
* Creates a token for connecting to an OpenTok session. In order to authenticate a user
* connecting to an OpenTok session, the client passes a token when connecting to the session.
* <p>
* For testing, you can also use the <a href="https://dashboard.tokbox.com/projects">OpenTok
* dashboard</a> page to generate test tokens.
*
* @param string $sessionId The session ID corresponding to the session to which the user
* will connect.
*
* @param array $options This array defines options for the token. This array includes the
* following keys, all of which are optional:
*
* <ul>
*
* <li><code>'role'</code> (string) — One of the constants defined in the RoleConstants
* class. The default role is publisher</li>
*
* <li><code>'expireTime'</code> (int) — The timestamp for when the token expires,
* in milliseconds since the Unix epoch. The default expiration time is 24 hours
* after the token creation time. The maximum expiration time is 30 days after the
* token creation time.</li>
*
* <li><code>'data'</code> (string) — A string containing connection metadata
* describing the end-user. For example, you can pass the user ID, name, or other data
* describing the end-user. The length of the string is limited to 1000 characters.
* This data cannot be updated once it is set.</li>
*
* </ul>
*
* @return string The token string.
*/
public function generateToken($sessionId, $options = array())
{
// unpack optional arguments (merging with default values) into named variables
$defaults = array('role' => Role::PUBLISHER, 'expireTime' => null, 'data' => null);
$options = array_merge($defaults, array_intersect_key($options, $defaults));
list($role, $expireTime, $data) = array_values($options);
// additional token data
$createTime = time();
$nonce = microtime(true) . mt_rand();
// validate arguments
Validators::validateSessionIdBelongsToKey($sessionId, $this->apiKey);
Validators::validateRole($role);
Validators::validateExpireTime($expireTime, $createTime);
Validators::validateData($data);
$dataString = "session_id={$sessionId}&create_time={$createTime}&role={$role}&nonce={$nonce}" . ($expireTime ? "&expire_time={$expireTime}" : '') . ($data ? "&connection_data=" . urlencode($data) : '');
$sig = $this->_sign_string($dataString, $this->apiSecret);
return "T1==" . base64_encode("partner_id={$this->apiKey}&sig={$sig}:{$dataString}");
}