<?php
/**
 * HexaDNS - DNS Lookup API
 *
 * Führt echte DNS-Abfragen durch und gibt die Ergebnisse als JSON zurück.
 *
 * Verwendung: GET /api/dns-lookup.php?domain=example.com
 */

require_once __DIR__ . '/../includes/api-helpers.php';

// CORS Headers für Frontend-Zugriff
header('Content-Type: application/json; charset=utf-8');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, OPTIONS');
header('Access-Control-Allow-Headers: Content-Type');

// Preflight request handling
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(200);
    exit;
}

if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
    http_response_code(405);
    echo json_encode(['error' => 'Nur GET-Anfragen erlaubt']);
    exit;
}

if (!checkApiRateLimit('dns-lookup')) {
    rejectApiRateLimit();
}

$domain = getValidatedDomainParam();

if ($domain === null) {
    http_response_code(400);
    echo json_encode(['error' => empty($_GET['domain']) ? 'Domain-Parameter fehlt' : 'Ungültiges Domain-Format']);
    exit;
}

// DNS-Abfrage durchführen
$startTime = microtime(true);
$result = performDnsLookup($domain);
$queryTime = round((microtime(true) - $startTime) * 1000, 2);

// Ergebnis zurückgeben
echo json_encode([
    'success' => true,
    'domain' => $domain,
    'query_time_ms' => $queryTime,
    'timestamp' => date('Y-m-d H:i:s'),
    'records' => $result
], JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);

/**
 * Führt DNS-Lookup für verschiedene Record-Typen durch
 */
function performDnsLookup(string $domain): array {
    $records = [
        'A' => [],
        'AAAA' => [],
        'MX' => [],
        'NS' => [],
        'TXT' => [],
        'CNAME' => [],
        'SOA' => []
    ];
    
    // A-Records (IPv4)
    $aRecords = @dns_get_record($domain, DNS_A);
    if ($aRecords) {
        foreach ($aRecords as $record) {
            $records['A'][] = [
                'ip' => $record['ip'],
                'ttl' => $record['ttl']
            ];
        }
    }
    
    // AAAA-Records (IPv6)
    $aaaaRecords = @dns_get_record($domain, DNS_AAAA);
    if ($aaaaRecords) {
        foreach ($aaaaRecords as $record) {
            $records['AAAA'][] = [
                'ipv6' => $record['ipv6'],
                'ttl' => $record['ttl']
            ];
        }
    }
    
    // MX-Records (Mail)
    $mxRecords = @dns_get_record($domain, DNS_MX);
    if ($mxRecords) {
        foreach ($mxRecords as $record) {
            $records['MX'][] = [
                'target' => $record['target'],
                'priority' => $record['pri'],
                'ttl' => $record['ttl']
            ];
        }
        // Nach Priorität sortieren
        usort($records['MX'], fn($a, $b) => $a['priority'] <=> $b['priority']);
    }
    
    // NS-Records (Nameserver)
    $nsRecords = @dns_get_record($domain, DNS_NS);
    if ($nsRecords) {
        foreach ($nsRecords as $record) {
            $records['NS'][] = [
                'target' => $record['target'],
                'ttl' => $record['ttl']
            ];
        }
    }
    
    // TXT-Records
    $txtRecords = @dns_get_record($domain, DNS_TXT);
    if ($txtRecords) {
        foreach ($txtRecords as $record) {
            $records['TXT'][] = [
                'txt' => $record['txt'],
                'ttl' => $record['ttl']
            ];
        }
    }
    
    // CNAME-Records
    $cnameRecords = @dns_get_record($domain, DNS_CNAME);
    if ($cnameRecords) {
        foreach ($cnameRecords as $record) {
            $records['CNAME'][] = [
                'target' => $record['target'],
                'ttl' => $record['ttl']
            ];
        }
    }
    
    // SOA-Record (Start of Authority)
    $soaRecords = @dns_get_record($domain, DNS_SOA);
    if ($soaRecords) {
        foreach ($soaRecords as $record) {
            $records['SOA'][] = [
                'mname' => $record['mname'] ?? '',
                'rname' => $record['rname'] ?? '',
                'serial' => $record['serial'] ?? 0,
                'refresh' => $record['refresh'] ?? 0,
                'retry' => $record['retry'] ?? 0,
                'expire' => $record['expire'] ?? 0,
                'minimum_ttl' => $record['minimum-ttl'] ?? 0,
                'ttl' => $record['ttl']
            ];
        }
    }
    
    // Leere Arrays entfernen
    return array_filter($records, fn($arr) => !empty($arr));
}