<?php
/**
 * DNS NS Record Lookup API
 * Endpoint: /dns-tools-get-ns-record
 * Method: POST
 * Content-Type: application/json
 */

header('Content-Type: application/json; charset=utf-8');

// Allow only POST requests
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode([
        'success' => false,
        'message' => 'Only POST method allowed'
    ]);
    exit;
}

// Read JSON body
$input = json_decode(file_get_contents('php://input'), true);
$domain = $input['domain'] ?? '';

// Domain validation
function validateDomain(string $domain): bool
{
    return (bool) preg_match(
        '/^(?!-)(?:[a-zA-Z0-9-]{1,63}\.)+[a-zA-Z]{2,}$/',
        $domain
    );
}

if (!$domain || !validateDomain($domain)) {
    http_response_code(400);
    echo json_encode([
        'success' => false,
        'message' => 'Invalid domain'
    ]);
    exit;
}

// Fetch NS records
$records = dns_get_record($domain, DNS_NS);
$nsRecords = [];

if ($records !== false) {
    foreach ($records as $record) {
        if (!empty($record['target'])) {
            $nsRecords[] = $record['target'];
        }
    }
}

// Response
if (empty($nsRecords)) {
    echo json_encode([
        'success' => false,
        'domain'  => $domain,
        'message' => 'No NS records found',
        'records' => []
    ]);
    exit;
}

echo json_encode([
    'success' => true,
    'domain'  => $domain,
    'records' => $nsRecords
]);