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    <h3>Editing: HoursField.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

declare(strict_types=1);

namespace Cron;

use DateTimeInterface;
use DateTimeZone;

/**
 * Hours field.  Allows: * , / -.
 */
class HoursField extends AbstractField
{
    /**
     * {@inheritdoc}
     */
    protected $rangeStart = 0;

    /**
     * {@inheritdoc}
     */
    protected $rangeEnd = 23;

    /**
     * @var array|null Transitions returned by DateTimeZone::getTransitions()
     */
    protected $transitions = [];

    /**
     * @var int|null Timestamp of the start of the transitions range
     */
    protected $transitionsStart = null;

    /**
     * @var int|null Timestamp of the end of the transitions range
     */
    protected $transitionsEnd = null;

    /**
     * {@inheritdoc}
     */
    public function isSatisfiedBy(DateTimeInterface $date, $value, bool $invert): bool
    {
        $checkValue = (int) $date-&gt;format('H');
        $retval = $this-&gt;isSatisfied($checkValue, $value);
        if ($retval) {
            return $retval;
        }

        // Are we on the edge of a transition
        $lastTransition = $this-&gt;getPastTransition($date);
        if (($lastTransition !== null) &amp;&amp; ($lastTransition[&quot;ts&quot;] &gt; ((int) $date-&gt;format('U') - 3600))) {
            $dtLastOffset = clone $date;
            $this-&gt;timezoneSafeModify($dtLastOffset, &quot;-1 hour&quot;);
            $lastOffset = $dtLastOffset-&gt;getOffset();

            $dtNextOffset = clone $date;
            $this-&gt;timezoneSafeModify($dtNextOffset, &quot;+1 hour&quot;);
            $nextOffset = $dtNextOffset-&gt;getOffset();

            $offsetChange = $nextOffset - $lastOffset;
            if ($offsetChange &gt;= 3600) {
                $checkValue -= 1;
                return $this-&gt;isSatisfied($checkValue, $value);
            }
            if ((! $invert) &amp;&amp; ($offsetChange &lt;= -3600)) {
                $checkValue += 1;
                return $this-&gt;isSatisfied($checkValue, $value);
            }
        }

        return $retval;
    }

    public function getPastTransition(DateTimeInterface $date): ?array
    {
        $currentTimestamp = (int) $date-&gt;format('U');
        if (
            ($this-&gt;transitions === null)
            || ($this-&gt;transitionsStart &lt; ($currentTimestamp + 86400))
            || ($this-&gt;transitionsEnd &gt; ($currentTimestamp - 86400))
        ) {
            // We start a day before current time so we can differentiate between the first transition entry
            // and a change that happens now
            $dtLimitStart = clone $date;
            $dtLimitStart = $dtLimitStart-&gt;modify(&quot;-12 months&quot;);
            $dtLimitEnd = clone $date;
            $dtLimitEnd = $dtLimitEnd-&gt;modify('+12 months');

            $this-&gt;transitions = $date-&gt;getTimezone()-&gt;getTransitions(
                $dtLimitStart-&gt;getTimestamp(),
                $dtLimitEnd-&gt;getTimestamp()
            );
            if (empty($this-&gt;transitions)) {
                return null;
            }
            $this-&gt;transitionsStart = $dtLimitStart-&gt;getTimestamp();
            $this-&gt;transitionsEnd = $dtLimitEnd-&gt;getTimestamp();
        }

        $nextTransition = null;
        foreach ($this-&gt;transitions as $transition) {
            if ($transition[&quot;ts&quot;] &gt; $currentTimestamp) {
                continue;
            }

            if (($nextTransition !== null) &amp;&amp; ($transition[&quot;ts&quot;] &lt; $nextTransition[&quot;ts&quot;])) {
                continue;
            }

            $nextTransition = $transition;
        }

        return ($nextTransition ?? null);
    }

    /**
     * {@inheritdoc}
     *
     * @param string|null                  $parts
     */
    public function increment(DateTimeInterface &amp;$date, $invert = false, $parts = null): FieldInterface
    {
        $originalTimestamp = (int) $date-&gt;format('U');

        // Change timezone to UTC temporarily. This will
        // allow us to go back or forwards and hour even
        // if DST will be changed between the hours.
        if (null === $parts || '*' === $parts) {
            if ($invert) {
                $date = $date-&gt;sub(new \DateInterval('PT1H'));
            } else {
                $date = $date-&gt;add(new \DateInterval('PT1H'));
            }

            $date = $this-&gt;setTimeHour($date, $invert, $originalTimestamp);
            return $this;
        }

        $parts = false !== strpos($parts, ',') ? explode(',', $parts) : [$parts];
        $hours = [];
        foreach ($parts as $part) {
            $hours = array_merge($hours, $this-&gt;getRangeForExpression($part, 23));
        }

        $current_hour = (int) $date-&gt;format('H');
        $position = $invert ? \count($hours) - 1 : 0;
        $countHours = \count($hours);
        if ($countHours &gt; 1) {
            for ($i = 0; $i &lt; $countHours - 1; ++$i) {
                if ((!$invert &amp;&amp; $current_hour &gt;= $hours[$i] &amp;&amp; $current_hour &lt; $hours[$i + 1]) ||
                    ($invert &amp;&amp; $current_hour &gt; $hours[$i] &amp;&amp; $current_hour &lt;= $hours[$i + 1])) {
                    $position = $invert ? $i : $i + 1;

                    break;
                }
            }
        }

        $target = (int) $hours[$position];
        $originalHour = (int)$date-&gt;format('H');

        $originalDay = (int)$date-&gt;format('d');
        $previousOffset = $date-&gt;getOffset();

        if (! $invert) {
            if ($originalHour &gt;= $target) {
                $distance = 24 - $originalHour;
                $date = $this-&gt;timezoneSafeModify($date, &quot;+{$distance} hours&quot;);

                $actualDay = (int)$date-&gt;format('d');
                $actualHour = (int)$date-&gt;format('H');
                if (($actualDay !== ($originalDay + 1)) &amp;&amp; ($actualHour !== 0)) {
                    $offsetChange = ($previousOffset - $date-&gt;getOffset());
                    $date = $this-&gt;timezoneSafeModify($date, &quot;+{$offsetChange} seconds&quot;);
                }

                $originalHour = (int)$date-&gt;format('H');
            }

            $distance = $target - $originalHour;
            $date = $this-&gt;timezoneSafeModify($date, &quot;+{$distance} hours&quot;);
        } else {
            if ($originalHour &lt;= $target) {
                $distance = ($originalHour + 1);
                $date = $this-&gt;timezoneSafeModify($date, &quot;-&quot; . $distance . &quot; hours&quot;);

                $actualDay = (int)$date-&gt;format('d');
                $actualHour = (int)$date-&gt;format('H');
                if (($actualDay !== ($originalDay - 1)) &amp;&amp; ($actualHour !== 23)) {
                    $offsetChange = ($previousOffset - $date-&gt;getOffset());
                    $date = $this-&gt;timezoneSafeModify($date, &quot;+{$offsetChange} seconds&quot;);
                }

                $originalHour = (int)$date-&gt;format('H');
            }

            $distance = $originalHour - $target;
            $date = $this-&gt;timezoneSafeModify($date, &quot;-{$distance} hours&quot;);
        }

        $date = $this-&gt;setTimeHour($date, $invert, $originalTimestamp);

        $actualHour = (int)$date-&gt;format('H');
        if ($invert &amp;&amp; ($actualHour === ($target - 1) || (($actualHour === 23) &amp;&amp; ($target === 0)))) {
            $date = $this-&gt;timezoneSafeModify($date, &quot;+1 hour&quot;);
        }

        return $this;
    }
}
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