Imap::authenticate

public function authenticate(&$error)
{
	$error = null;

	if (!$this->connect($error))
		return false;
	if (in_array($this->sessState, array('auth', 'select')))
		return true;

	$mech = false;
	$token = null;

	if (preg_match('/ x20 AUTH=XOAUTH2 ( x20 | rn ) /ix', $this->sessCapability))
	{
		$token = HelperOAuth::getTokenByMeta($this->options['password']);

		if (!empty($token))
		{
			$mech = 'oauth';
		}
		else if (false === $token)
		{
			$error = $this->errorMessage(array(Imap::ERR_AUTH, Imap::ERR_AUTH_OAUTH));
			return false;
		}
	}

	if ($mech == false)
	{
		if (preg_match('/ x20 AUTH=PLAIN ( x20 | rn ) /ix', $this->sessCapability))
			$mech = 'plain';
		elseif (!preg_match('/ x20 LOGINDISABLED ( x20 | rn ) /ix', $this->sessCapability))
			$mech = 'login';
	}

	if (!$mech)
	{
		$error = $this->errorMessage(array(Imap::ERR_AUTH, Imap::ERR_AUTH_MECH));
		return false;
	}

	if ($mech == 'oauth')
	{
		$response = $this->executeCommand('AUTHENTICATE XOAUTH2', $error);

		if (mb_strpos($response, '+') !== 0)
		{
			$error = $error == Imap::ERR_COMMAND_REJECTED ? Imap::ERR_AUTH_MECH : $error;
			$error = $this->errorMessage(array(Imap::ERR_AUTH, $error), $response);

			return false;
		}

		$response = $this->exchange(base64_encode(sprintf(
			"user=%sx01auth=Bearer %sx01x01", $this->options['login'], $token
		)), $error);

		if (mb_strpos($response, '+') === 0)
			$response = $this->exchange("rn", $error);
	}
	elseif ($mech == 'plain')
	{
		$response = $this->executeCommand('AUTHENTICATE PLAIN', $error);

		if (mb_strpos($response, '+') !== 0)
		{
			$error = $error == Imap::ERR_COMMAND_REJECTED ? Imap::ERR_AUTH_MECH : $error;
			$error = $this->errorMessage(array(Imap::ERR_AUTH, $error), $response);

			return false;
		}

		$response = $this->exchange(base64_encode(sprintf(
			"x00%sx00%s",
			Encoding::convertEncoding($this->options['login'], $this->options['encoding'], 'UTF-8'),
			Encoding::convertEncoding($this->options['password'], $this->options['encoding'], 'UTF-8')
		)), $error);
	}
	else // if ($mech == 'login')
	{
		$response = $this->executeCommand(sprintf(
			'LOGIN %s %s',
			static::prepareString($this->options['login']),
			static::prepareString($this->options['password'])
		), $error);
	}

	if ($error)
	{
		$error = $error == Imap::ERR_COMMAND_REJECTED ? null : $error;
		$error = $this->errorMessage(array(Imap::ERR_AUTH, $error), $response);

		return false;
	}

	$this->sessState = 'auth';

	if (!$this->capability($error))
		return false;

	return true;
}