/**
 * Get base domain of network.
 *
 * @since 3.0.0
 * @return string Base domain.
 */
function get_clean_basedomain()
{
    if ($existing_domain = network_domain_check()) {
        return $existing_domain;
    }
    $domain = preg_replace('|https?://|', '', get_option('siteurl'));
    if ($slash = strpos($domain, '/')) {
        $domain = substr($domain, 0, $slash);
    }
    return $domain;
}

 protected function gather()
 {
     $results = [];
     // Multisite
     $results[] = ['method' => 'info', 'message' => 'Multisite: ' . yesno(is_multisite())];
     // Blog tables
     if (is_blog_installed()) {
         $results[] = ['method' => 'info', 'message' => 'Blog installed: ' . yesno(true)];
     } else {
         $results[] = ['method' => 'error', 'message' => 'Blog installed: ' . yesno(false)];
     }
     // php.ini
     $results[] = ['method' => 'info', 'message' => 'post_max_size: ' . ini_get('post_max_size')];
     $results[] = ['method' => 'info', 'message' => 'upload_max_filesize: ' . ini_get('upload_max_filesize')];
     if (env('WP_MULTISITE')) {
         $this->info('Network Domain: ', network_domain_check());
     } else {
     }
     return $results;
 }

if ($_POST) {
    check_admin_referer('install-network-1');
    require_once ABSPATH . 'wp-admin/includes/upgrade.php';
    // Create network tables.
    install_network();
    $base = parse_url(trailingslashit(get_option('home')), PHP_URL_PATH);
    $subdomain_install = allow_subdomain_install() ? !empty($_POST['subdomain_install']) : false;
    if (!network_domain_check()) {
        $result = populate_network(1, get_clean_basedomain(), sanitize_email($_POST['email']), wp_unslash($_POST['sitename']), $base, $subdomain_install);
        if (is_wp_error($result)) {
            if (1 == count($result->get_error_codes()) && 'no_wildcard_dns' == $result->get_error_code()) {
                network_step2($result);
            } else {
                network_step1($result);
            }
        } else {
            network_step2();
        }
    } else {
        network_step2();
    }
} elseif (is_multisite() || network_domain_check()) {
    network_step2();
} else {
    network_step1();
}
?>
</div>

<?php 
include ABSPATH . 'wp-admin/admin-footer.php';