Simple ABC test Groups delegate

abc-delegate.php

<?php

$abcGroups = ['A', 'B', 'C'];

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);

if (!isset($_COOKIE['abc_group'])) {
    $lastUsedAbcGroupNumber = $redis->get('last_used_abc_group_number');

    if (false === $lastUsedAbcGroupNumber) {
        $nextAbcGroupNumber = 0;
    } else {
        $nextAbcGroupNumber = ($lastUsedAbcGroupNumber >= 2) ? 0 : $lastUsedAbcGroupNumber + 1;
    }

    setcookie('abc_group', $abcGroups[$nextAbcGroupNumber]);
    $redis->set('last_used_abc_group_number', $nextAbcGroupNumber);
}

if (isset($_COOKIE['abc_group'])) {
    echo "Вас определили в группу: " . $_COOKIE['abc_group'];
}