<?php


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

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');

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

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


$dnsServers = [
    ['name' => 'Google', 'ip' => '8.8.8.8', 'location' => 'Global'],
    ['name' => 'Google Secondary', 'ip' => '8.8.4.4', 'location' => 'Global'],
    ['name' => 'Cloudflare', 'ip' => '1.1.1.1', 'location' => 'Global'],
    ['name' => 'Cloudflare Secondary', 'ip' => '1.0.0.1', 'location' => 'Global'],
    ['name' => 'Quad9', 'ip' => '9.9.9.9', 'location' => 'Global'],
    ['name' => 'OpenDNS', 'ip' => '208.67.222.222', 'location' => 'USA'],
    ['name' => 'Comodo', 'ip' => '8.26.56.26', 'location' => 'USA'],
    ['name' => 'Level3', 'ip' => '4.2.2.1', 'location' => 'USA'],
];

$domain = getValidatedDomainParam();
$type = isset($_GET['type']) ? strtoupper(trim($_GET['type'])) : 'A';

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


$allowedTypes = ['A', 'AAAA', 'MX', 'NS', 'TXT', 'CNAME'];
if (!in_array($type, $allowedTypes)) {
    $type = 'A';
}

$results = [];
$startTime = microtime(true);

foreach ($dnsServers as $server) {
    $serverResult = [
        'server' => $server['name'],
        'ip' => $server['ip'],
        'location' => $server['location'],
        'records' => [],
        'status' => 'success',
        'response_time' => 0
    ];
    
    $queryStart = microtime(true);
    
    
    $records = queryDnsServer($domain, $type, $server['ip']);
    
    $serverResult['response_time'] = round((microtime(true) - $queryStart) * 1000, 2);
    $serverResult['records'] = $records;
    
    if (empty($records)) {
        $serverResult['status'] = 'no_records';
    }
    
    $results[] = $serverResult;
}

$totalTime = round((microtime(true) - $startTime) * 1000, 2);


$propagationStatus = calculatePropagationStatus($results);

echo json_encode([
    'success' => true,
    'domain' => $domain,
    'record_type' => $type,
    'propagation_status' => $propagationStatus,
    'total_time_ms' => $totalTime,
    'timestamp' => date('Y-m-d H:i:s'),
    'servers' => $results
], JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);


function queryDnsServer(string $domain, string $type, string $server): array {
    $records = [];
    
    
    $digResult = @shell_exec(
        'dig @' . escapeshellarg($server) . ' '
        . escapeshellarg($domain) . ' '
        . escapeshellarg($type)
        . ' +short +time=2 +tries=1 2>/dev/null'
    );
    
    if ($digResult !== null && trim($digResult) !== '') {
        $lines = array_filter(explode("\n", trim($digResult)));
        foreach ($lines as $line) {
            $records[] = trim($line);
        }
        return $records;
    }
    
    
    $dnsType = constant('DNS_' . $type);
    $result = @dns_get_record($domain, $dnsType);
    
    if ($result) {
        foreach ($result as $record) {
            switch ($type) {
                case 'A':
                    $records[] = $record['ip'] ?? '';
                    break;
                case 'AAAA':
                    $records[] = $record['ipv6'] ?? '';
                    break;
                case 'MX':
                    $records[] = ($record['pri'] ?? '') . ' ' . ($record['target'] ?? '');
                    break;
                case 'NS':
                case 'CNAME':
                    $records[] = $record['target'] ?? '';
                    break;
                case 'TXT':
                    $records[] = $record['txt'] ?? '';
                    break;
            }
        }
    }
    
    return array_filter($records);
}


function calculatePropagationStatus(array $results): array {
    $totalServers = count($results);
    $serversWithRecords = 0;
    $allRecords = [];
    
    foreach ($results as $result) {
        if (!empty($result['records'])) {
            $serversWithRecords++;
            foreach ($result['records'] as $record) {
                $allRecords[] = $record;
            }
        }
    }
    
    
    $uniqueRecords = array_unique($allRecords);
    
    
    $isConsistent = count($uniqueRecords) <= 1 || $serversWithRecords === 0;
    
    $percentage = $totalServers > 0 ? round(($serversWithRecords / $totalServers) * 100) : 0;
    
    return [
        'percentage' => $percentage,
        'servers_responding' => $serversWithRecords,
        'total_servers' => $totalServers,
        'is_consistent' => $isConsistent,
        'unique_values' => array_values($uniqueRecords)
    ];
}