Notify::removeDuplicateChatAgent

static function removeDuplicateChatAgent()
{
	$hasDuplicate = false;
	$connection = BitrixMainApplication::getInstance()->getConnection();
	$users = $connection->query("
		SELECT AUTHOR_ID, COUNT(1) CNT 
		FROM b_im_chat
		WHERE TYPE = '".IM_MESSAGE_SYSTEM."'
		GROUP BY AUTHOR_ID
		HAVING CNT > 1
		LIMIT 100
	");
	while ($userData = $users->fetch())
	{
		$hasDuplicate = true;

		$result = Array();
		$chats = $connection->query("
			SELECT ID, LAST_MESSAGE_ID
			FROM b_im_chat
			WHERE TYPE = '".IM_MESSAGE_SYSTEM."' AND AUTHOR_ID = ".intval($userData['AUTHOR_ID'])."
		");
		while ($chatData = $chats->fetch())
		{
			$result[intval($chatData['ID'])] = intval($chatData['LAST_MESSAGE_ID']);
		}
		arsort($result);
		$result = array_slice($result, 1, null, true);
		$chatId = array_keys($result);
		if (!empty($chatId))
		{
			$connection->query("DELETE FROM b_im_relation WHERE CHAT_ID IN (".implode(", ", $chatId).")");
			$connection->query("DELETE FROM b_im_chat WHERE ID IN (".implode(", ", $chatId).")");
		}
	}

	return $hasDuplicate? "BitrixImUpdateNotify::removeDuplicateChatAgent();": "";
}