PHP Secret Santa 脚本：解决奇数用户配对问题

function generateUsers(array $defaultUsers, array $updatedUsers = []): bool
{
    $users = (!empty($updatedUsers)) ? $updatedUsers : $defaultUsers;

    if (count($users) > 1) {
        if ($this->matchedUsers !== count($this->startingUsers)) {
            // Pick random user and match with current user. Reset array and repeat until 1 or no users left.
            $randomUserIndex = rand(1, count($users) - 1);
            $this->pairs[] = [$users[0], $users[$randomUserIndex]];
            unset($users[$randomUserIndex]);
            unset($users[0]);

            // Remove pair from list so they can't be assigned again. Reset array for 0 based index $users[0]
            $newUsers = array_values($users);
            // Check that there are two or more users
            if(count($newUsers) > 1){
                $this->generateUsers($this->startingUsers, $newUsers);
            }
            $this->matchedUsers += 2;
        }
    }

    // If only one user remains can't allocate a Pair
    if (count($users) === 1) {
        $orderedUsers = array_values($users);
        $this->pairs[] = [$orderedUsers[0], "No Pair"];

        return true;
    }

    return true;
}

class Match
{
    protected $startingUsers = [
        "User1",
        "User2",
        "User3",
        "User4",
        "User5",
    ];

    protected $pairs = [];

    function getPairs(): array
    {
        $users = $this->startingUsers;
        shuffle($users); // 打乱用户顺序

        for ($i = 0; $i < count($users); $i++) {
            $giver = $users[$i];
            $receiver = $users[($i + 1) % count($users)]; // 使用模运算实现循环
            $this->pairs[] = [$giver, $receiver];
        }

        return $this->pairs;
    }
}

$match = new Match();

foreach ($match->getPairs() as $pair) {
    echo "$pair[0] gets $pair[1]";
    echo "\n";
}