Action::checkAccess

static function checkAccess(int $messageId)
{
	global $USER;
	$userId = $USER->GetId();
	if ($userId <= 0)
	{
		return false;
	}

	$orm = BitrixImModelMessageTable::getById($messageId);
	$message = $orm->fetch();

	if(!$message)
	{
		return false;
	}

	$orm = BitrixImModelChatTable::getById($message['CHAT_ID']);
	$chat = $orm->fetch();
	if (!$chat)
	{
		return false;
	}

	$relations = CIMChat::GetRelationById($message['CHAT_ID'], false, true, false);
	if (!isset($relations[$userId]))
	{
		return false;
	}

	return true;
}