CIMHistory::RemoveAllMessage

function RemoveAllMessage($userId)
{
	global $DB;

	$userId = intval($userId);

	if ($this->user_id == $userId)
	{
		return false;
	}

	$strSql ="
		SELECT
			MAX(M.ID)+1 MAX_ID,
			M.CHAT_ID,
			R1.ID R1_ID,
			R1.START_ID R1_START_ID,
			R2.ID R2_ID,
			R2.START_ID R2_START_ID
		FROM b_im_relation R1
		INNER JOIN b_im_relation R2 on R2.CHAT_ID = R1.CHAT_ID
		INNER JOIN b_im_message M ON M.ID >= R1.START_ID AND M.CHAT_ID = R1.CHAT_ID
		WHERE
			R1.USER_ID = ".$this->user_id."
		AND R2.USER_ID = ".$userId."
		AND R1.MESSAGE_TYPE = '".IM_MESSAGE_PRIVATE."'
		GROUP BY M.CHAT_ID, R1.ID, R1.START_ID, R2.ID, R2.START_ID
	";
	$dbRes = $DB->Query($strSql, false, "File: ".__FILE__."
Line: ".__LINE__);
	if ($arRes = $dbRes->Fetch())
	{
		$strSql = "UPDATE b_im_relation SET START_ID = ".intval($arRes['MAX_ID'])." WHERE ID = ".intval($arRes['R1_ID']);
		$DB->Query($strSql, false, "File: ".__FILE__."
Line: ".__LINE__);

		$counterService = new IMV2MessageCounterService($this->user_id);

		$counterService->deleteByChatId((int)$arRes['CHAT_ID']);

		if ($arRes['MAX_ID'] >= $arRes['R2_START_ID'] && $arRes['R2_START_ID'] > 0)
		{
			$messages = IMModelMessageTable::getList(array(
														   'select' => array('ID'),
														   'filter' => array(
															   ' $arRes['R2_START_ID'],
															   '=CHAT_ID' => $arRes['CHAT_ID'],
														   ),
													   ));
			while ($messageInfo = $messages->fetch())
			{
				IMModelMessageTable::delete($messageInfo['ID']);
			}
		}

		$primaryKey = ['USER_ID' => $this->user_id, 'ITEM_TYPE' => IM_MESSAGE_PRIVATE, 'ITEM_ID' => $userId];
		IMModelRecentTable::update($primaryKey, ['ITEM_MID' => 0]);
	}

	return true;
}