$queueConn = $conn_master ?? $conn;

$queueId = 0;
$targetUrl = '';
$domainId = 0;

try {

    $rawDomain = $_SERVER['HTTP_HOST'] ?? '';
    $currentDomain = preg_replace('/^www\./i', '', $rawDomain);
    $currentDomain = explode(':', $currentDomain)[0];

    mysqli_begin_transaction($queueConn);

    $stmt = mysqli_prepare($queueConn, "
        SELECT
            q.id,
            q.url,
            d.id AS domain_id
        FROM link_queue q
        INNER JOIN users u
            ON q.user = u.id
        INNER JOIN domains d
            ON d.domain_name = ?
           AND d.status = '1'
        WHERE q.status = 'pending'
          AND (
                u.allowed_domains = 'all'
                OR FIND_IN_SET(d.id, u.allowed_domains) > 0
          )
        ORDER BY q.id ASC
        LIMIT 1
        FOR UPDATE SKIP LOCKED
    ");

    if (!$stmt) {
        throw new Exception(mysqli_error($queueConn));
    }

    mysqli_stmt_bind_param($stmt, "s", $currentDomain);
    mysqli_stmt_execute($stmt);

    $result = mysqli_stmt_get_result($stmt);

    if (!$result || !($row = mysqli_fetch_assoc($result))) {
        mysqli_stmt_close($stmt);
        mysqli_commit($queueConn);

        http_response_code(200);
        echo "";
        exit;
    }

    $queueId = (int)$row['id'];
    $targetUrl = trim((string)$row['url']);
    $domainId = (int)$row['domain_id'];

    mysqli_stmt_close($stmt);

    // ------------------------------------------------------
    // Claim the job
    // ------------------------------------------------------

    $claim = mysqli_prepare(
        $queueConn,
        "UPDATE link_queue
         SET status='processing'
         WHERE id=?"
    );

    if (!$claim) {
        throw new Exception(mysqli_error($queueConn));
    }

    mysqli_stmt_bind_param($claim, "i", $queueId);
    mysqli_stmt_execute($claim);
    mysqli_stmt_close($claim);

    // Release row lock immediately
    mysqli_commit($queueConn);

    // ------------------------------------------------------
    // Finish processing
    // ------------------------------------------------------

    mysqli_begin_transaction($queueConn);

    $done = mysqli_prepare(
        $queueConn,
        "UPDATE link_queue
         SET status='done'
         WHERE id=?"
    );

    if (!$done) {
        throw new Exception(mysqli_error($queueConn));
    }

    mysqli_stmt_bind_param($done, "i", $queueId);
    mysqli_stmt_execute($done);
    mysqli_stmt_close($done);

    if ($domainId > 0) {

        $updateDomain = mysqli_prepare(
            $queueConn,
            "UPDATE domains
             SET total_redirected = total_redirected + 1
             WHERE id=?"
        );

        if (!$updateDomain) {
            throw new Exception(mysqli_error($queueConn));
        }

        mysqli_stmt_bind_param($updateDomain, "i", $domainId);
        mysqli_stmt_execute($updateDomain);
        mysqli_stmt_close($updateDomain);
    }

    mysqli_commit($queueConn);

    header('X-Robots-Tag: noindex, nofollow');
    header('Cache-Control: no-cache, no-store, must-revalidate');
    header('Pragma: no-cache');
    header('Expires: 0');
    header('Location: ' . $targetUrl, true, 301);
    exit;

} catch (Throwable $e) {

    @mysqli_rollback($queueConn);

    if ($queueId > 0) {

        $reset = mysqli_prepare(
            $queueConn,
            "UPDATE link_queue
             SET status='pending'
             WHERE id=?
               AND status='processing'"
        );

        if ($reset) {
            mysqli_stmt_bind_param($reset, "i", $queueId);
            mysqli_stmt_execute($reset);
            mysqli_stmt_close($reset);
        }
    }

    error_log("Redirect Route Process Error: " . $e->getMessage());

    http_response_code(200);
    echo "";
    exit;
}