class.ilTestShuffler.php

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<?php

declare(strict_types=1);

use ILIAS\Refinery\Factory as Refinery;
use ILIAS\Refinery\Random\Seed\GivenSeed;
use ILIAS\Refinery\Random\Transformation\ShuffleTransformation;

class ilTestShuffler
{
    public const FIXED_SHUFFLER_SEED_MIN_LENGTH = 8;

    public function __construct(
        protected Refinery $refinery
    ) {
    }

    public function getAnswerShuffleFor(
        int $question_id,
        int $active_id,
        int $pass_id
    ): ShuffleTransformation {
        $fixedSeed = $this->buildFixedShufflerSeed($question_id, $pass_id, $active_id);
        return $this->refinery->random()->shuffleArray(new GivenSeed($fixedSeed));
    }

    protected function buildFixedShufflerSeed(int $question_id, int $pass_id, int $active_id): int
    {
        $seed = ($question_id + $pass_id) * $active_id;
        if (is_float($seed) && is_float($seed = $active_id + $pass_id)) {
            $seed = $active_id;
        }

        $div = ceil((10 ** (self::FIXED_SHUFFLER_SEED_MIN_LENGTH - 1)) / $seed);
        if ($div > 1) {
            $seed = $seed * ($div + $seed % 10);
        }
        return (int) $seed;
    }
}