paginator.php

<?php
namespace Bitrix\Main\DB;
class Paginator
{
    public static function query($sql, Connection $connection, $numberOfRecords, $pageNumber, $numberOfRecordsPerPage, $backward = false)
    {
        list($offset, $limit) = self::calculateQueryLimits(
            $numberOfRecords, $pageNumber, $numberOfRecordsPerPage, $backward
        );
 
        return $connection->query($sql, $offset, $limit);
    }
 
    public static function calculateQueryLimits($numberOfRecords, $pageNumber, $numberOfRecordsPerPage, $backward)
    {
        $pageNumber = intval($pageNumber);
        $numberOfRecords = intval($numberOfRecords);
 
        $numberOfRecordsPerPage = intval($numberOfRecordsPerPage);
        if ($numberOfRecordsPerPage <= 0)
            $numberOfRecordsPerPage = 10;
 
        $pageCount = floor($numberOfRecords / $numberOfRecordsPerPage);
        if ($backward)
        {
            $makeweight = ($numberOfRecords % $numberOfRecordsPerPage);
            if ($pageCount == 0 && $makeweight > 0)
                $pageCount = 1;
 
            if ($pageNumber < 1)
                $pageNumber = 1;
            if ($pageNumber > $pageCount)
                $pageNumber = $pageCount;
 
            $firstRecordToShow = 0;
            if ($pageNumber != $pageCount)
                $firstRecordToShow += $makeweight;
 
            $firstRecordToShow += ($pageCount - $pageNumber) * $numberOfRecordsPerPage;
            $lastRecordToShow = $makeweight + ($pageCount - $pageNumber + 1) * $numberOfRecordsPerPage;
        }
        else
        {
            if ($numberOfRecordsPerPage && ($numberOfRecords % $numberOfRecordsPerPage > 0))
                $pageCount++;
 
            if ($pageNumber < 1)
                $pageNumber = 1;
            if ($pageNumber > $pageCount)
                $pageNumber = $pageCount;
 
            $firstRecordToShow = $numberOfRecordsPerPage * ($pageNumber - 1);
            $lastRecordToShow = $numberOfRecordsPerPage * $pageNumber;
        }
 
        return array($firstRecordToShow, $lastRecordToShow - $firstRecordToShow);
    }
}