Подсчёт ночных часов

$time_min = '2023-09-26 20:00:00';
$time_max = '2023-09-27 08:00:00';

$time_min = '2023-09-26 23:00:00';
$time_max = '2023-09-27 03:00:00';

$time_min = '2023-09-26 22:00:00';
$time_max = '2023-09-27 06:00:00';
$hours = round((strtotime($time_max) - strtotime($time_min))/3600, 1);
echo $hours; // 8

<?php
 
$time_min = '2023-09-26 23:00:00';
$time_max = '2023-09-27 03:00:00';
$hours = round((strtotime($time_max) - strtotime($time_min))/3600, 1);
echo $hours; // 4

$list_time = [
    [
        '2023-09-26 20:00:00',
        '2023-09-27 08:00:00'
    ],
    [
        '2023-09-27 23:00:00',
        '2023-09-28 03:00:00'
    ],
    [
        '2023-09-28 21:00:00',
        '2023-09-29 09:00:00'
    ]
];
foreach($list_time as $time){
   $time[0] = ...;
   $time[1] = ...;
   ....
}

<?php
 
function hourDiff(string $startDate, string $endDate): int
{
    return round((strtotime($endDate) - strtotime($startDate)) / 3600, 1);
}
 
$listTime = [
    [
        '2023-09-26 19:00:00',
        '2023-09-27 08:00:00',
    ],
    [
        '2023-09-26 20:00:00',
        '2023-09-27 08:00:00',
    ],
    [
        '2023-09-27 23:00:00',
        '2023-09-28 03:00:00',
    ],
    [
        '2023-09-29 21:00:00',
        '2023-09-30 09:00:00',
    ],
];
 
foreach ($listTime as [$startDate, $endDate]) {
    $beginOffset  = 0;
    $expectedDate = (new \DateTime($startDate))->format("Y-m-d 20:00:00");
    if ($expectedDate > $startDate) {
        $beginOffset = hourDiff($startDate, $expectedDate);
    }
 
    $endOffset    = 0;
    $expectedDate = (new \DateTime($endDate))->format("Y-m-d 06:00:00");
    if ($expectedDate < $endDate) {
        $endOffset = hourDiff($expectedDate, $endDate);
    }
 
    echo hourDiff($startDate, $endDate) - $beginOffset - $endOffset, PHP_EOL;
}

$br="\r\n";
//$br='<br>';
$pers=[
0=>['from'=>'2023-09-26 23:00:00','to'=>'2023-09-27 03:00:00'],
1=>['from'=>'023-09-27 08:10:00','to'=>'2023-09-27 22:45:00'],
2=>['from'=>'2023-09-27 07:00:00','to'=>'2023-09-27 17:00:00']
];
foreach($pers AS $k => $r)
{
    $r['from']=strtotime($r['from']);
    $r['to']=strtotime($r['to']);
 
    if($r['to'] < $r['from'])
    {
        $tmp=$r['from'];
        $r['from']=$r['to'];
        $r['to']=$tmp;
        unset($tmp);
    }
 
    $sec=0;
    echo 'itrs:'.round($r['to']-$r['from']).$br;
    for($i=$r['from'];$i<=$r['to'];$i++)
    {
        //echo '.';
        $h=date('H',$i);
        if($h > 21)
        {
            $sec++;
        }
        else
        {
            if($h < 6)
            {
                $sec++;
            }
        }
    }
    echo date('d.m.Y H:i:s',$r['from']).' > '.date('d.m.Y H:i:s',$r['to']).$br;
    echo 'sec:'.$sec.' min:'.round($sec/60).' hrs:'.round($sec/60/60).$br.$br;
}

$pers = [
    ['from' => '2023-09-27 15:00:00', 'to' => '2023-09-28 02:00:00']
];