Ticks.php

<?php

declare(strict_types=1);

/*
 * This file is part of the PHP-CRON-EXPR package.
 *
 * (c) Jitendra Adhikari <jiten.adhikary@gmail.com>
 *     <https://github.com/adhocore>
 *
 * Licensed under MIT license.
 */

namespace Ahc\Cron;

use DateTime;

/**
 * Ticks for next/prev ticks of an expr based on given time.
 * Next tick support is experimental.
 * Prev tick is not yet implemented.
 */
class Ticks
{
    /** @var Expression */
    protected $expr;

    protected $limits = [
        ReferenceTime::MINUTE   => 60,
        ReferenceTime::HOUR     => 24,
        ReferenceTime::MONTHDAY => 31,
        ReferenceTime::MONTH    => 12,
        ReferenceTime::WEEKDAY  => 366,
        ReferenceTime::YEAR     => 100,
    ];

    public function __construct(Expression $expr)
    {
        $this->expr = $expr;
    }

    public function next(string $expr, $time = null): DateTime
    {
        $checker  = $this->expr->segmentChecker();
        $segments = $this->expr->segments($expr);

        $iter = 500;
        $ref  = new ReferenceTime($time);
        $ref->add(60 - $ref->timestamp % 60); // truncate seconds

        over:
        while ($iter > 0) {
            $iter--;
            foreach ($segments as $pos => $seg) {
                if ($seg === '*' || $seg === '?') {
                    continue;
                }
                [$new, $isOk] = $this->bumpUntilDue($checker, $seg, $pos, $ref);
                if ($isOk) {
                    $ref = $new;
                    goto over;
                }
            }
        }

        $date = $ref->dateTime();
        if ($this->expr->segmentsDue($segments, $date)) {
            return $date;
        }

        throw new \RuntimeException('Tried so hard');
    }

    private function bumpUntilDue(SegmentChecker $checker, string $seg, int $pos, ReferenceTime $ref): array
    {
        $iter = $this->limits[$pos];
        while ($iter > 0) {
            $iter--;
            if ($checker->setReference($ref)->checkDue($seg, $pos)) {
                return [$ref, true];
            }
            if ($pos === ReferenceTime::MINUTE) {
                $ref->add(60);
            } elseif ($pos === ReferenceTime::HOUR) {
                $ref->add(3600);
            } elseif ($pos === ReferenceTime::MONTHDAY || $pos === ReferenceTime::WEEKDAY) {
                $ref->add(86400);
            } elseif ($pos === ReferenceTime::MONTH) {
                $ref->addMonth();
            } elseif ($pos === ReferenceTime::YEAR) {
                $ref->addYear();
            }
        }

        return [$ref, false];
    }
}