<?php

declare(strict_types=1);

namespace Domovoy\Services\Discovery;

use Domovoy\Models\DiscoveredHost;
use Domovoy\Models\NetworkRange;
use Domovoy\Repositories\DiscoveredHostRepository;

class NetworkScanner
{
    private PingScanner $pingScanner;
    private TcpPortScanner $tcpPortScanner;
    private ArpTableReader $arpTableReader;
    private HostFingerprintService $fingerprintService;
    private DiscoveredHostRepository $discoveredHostRepository;

    /** @var int[] */
    private array $defaultPorts = [22, 23, 53, 80, 443, 445, 548, 631, 3306, 5432, 6379, 8000, 8080, 8443, 9000, 9090, 9100];

    public function __construct(
        PingScanner $pingScanner,
        TcpPortScanner $tcpPortScanner,
        ArpTableReader $arpTableReader,
        HostFingerprintService $fingerprintService,
        DiscoveredHostRepository $discoveredHostRepository
    ) {
        $this->pingScanner = $pingScanner;
        $this->tcpPortScanner = $tcpPortScanner;
        $this->arpTableReader = $arpTableReader;
        $this->fingerprintService = $fingerprintService;
        $this->discoveredHostRepository = $discoveredHostRepository;
    }

    /**
     * @return DiscoveredHost[]
     */
    public function scan(NetworkRange $range, ?int $scanJobId = null): array
    {
        $result = $this->scanResumable(
            $range,
            $scanJobId ?? 0,
            0,
            static fn (): bool => false,
            static function (array $state): void {
            }
        );

        return $result['hosts'];
    }

    /**
     * @return array{hosts: DiscoveredHost[], completed: bool, next_ip_index: int, total_ips: int, scanned_count: int, hosts_found: int}
     */
    public function scanResumable(
        NetworkRange $range,
        int $scanJobId,
        int $startIndex,
        callable $shouldStop,
        callable $onProgress
    ): array
    {
        $ips = $this->enumerateIps($range->cidr);
        $aliveHosts = [];
        $scannedCount = 0;
        $nextIndex = max(0, $startIndex);
        $arpEntries = $this->arpTableReader->read();

        $onProgress([
            'next_ip_index' => $nextIndex,
            'total_ips' => count($ips),
            'scanned_count' => $scannedCount,
            'hosts_found' => count($aliveHosts),
        ]);

        foreach ($ips as $index => $ip) {
            if ($index < $nextIndex) {
                continue;
            }

            if ($shouldStop()) {
                return [
                    'hosts' => $aliveHosts,
                    'completed' => false,
                    'next_ip_index' => $index,
                    'total_ips' => count($ips),
                    'scanned_count' => $scannedCount,
                    'hosts_found' => count($aliveHosts),
                ];
            }

            $nextIndex = $index + 1;
            $scannedCount++;

            // Step 1: Ping sweep
            if (!$this->pingScanner->ping($ip)) {
                $onProgress([
                    'next_ip_index' => $nextIndex,
                    'total_ips' => count($ips),
                    'scanned_count' => $scannedCount,
                    'hosts_found' => count($aliveHosts),
                ]);
                continue;
            }

            $host = new DiscoveredHost();
            $host->scanJobId = $scanJobId > 0 ? $scanJobId : null;
            $host->ipAddress = $ip;
            $host->firstSeen = new \DateTimeImmutable();
            $host->lastSeen = new \DateTimeImmutable();

            // Step 2: TCP port scan
            $openPorts = $this->tcpPortScanner->scan($ip, $this->defaultPorts, 200, 50);
            $host->openPorts = $openPorts;

            // Step 3: Reverse DNS
            $hostname = $this->resolveHostname($ip);
            $host->hostname = $hostname;

            // Step 4: Determine vendor by port patterns
            $host->vendor = $this->fingerprintService->guessVendor($openPorts, $hostname);

            // Step 5: Confidence score
            $host->confidence = $this->fingerprintService->calculateConfidence(count($openPorts), $hostname !== null);

            if (isset($arpEntries[$host->ipAddress])) {
                $host->macAddress = $arpEntries[$host->ipAddress]['mac'] ?? null;
                $host->vendor = $host->vendor ?: ($arpEntries[$host->ipAddress]['vendor'] ?? null);
            }

            $this->discoveredHostRepository->save($host);

            $aliveHosts[] = $host;
            $onProgress([
                'next_ip_index' => $nextIndex,
                'total_ips' => count($ips),
                'scanned_count' => $scannedCount,
                'hosts_found' => count($aliveHosts),
            ]);
        }

        return [
            'hosts' => $aliveHosts,
            'completed' => true,
            'next_ip_index' => $nextIndex,
            'total_ips' => count($ips),
            'scanned_count' => $scannedCount,
            'hosts_found' => count($aliveHosts),
        ];
    }

    /**
     * @return string[]
     */
    private function enumerateIps(string $cidr): array
    {
        if (!preg_match('#^(\d+\.\d+\.\d+\.\d+)/(\d{1,2})$#', $cidr, $matches)) {
            throw new \InvalidArgumentException("Invalid IPv4 CIDR: {$cidr}");
        }

        $baseIp = $matches[1];
        $mask = (int)$matches[2];
        if ($mask < 24) {
            throw new \InvalidArgumentException('Network ranges larger than /24 are disabled for the MVP scanner');
        }
        if ($mask > 32) {
            throw new \InvalidArgumentException("Invalid IPv4 CIDR mask: {$cidr}");
        }

        $base = ip2long($baseIp);
        if ($base === false) {
            throw new \InvalidArgumentException("Invalid IPv4 address: {$baseIp}");
        }

        $base = (int)sprintf('%u', $base);
        $hostCount = 2 ** (32 - $mask);
        $network = $base & ((0xFFFFFFFF << (32 - $mask)) & 0xFFFFFFFF);

        if ($mask === 32) {
            return [long2ip($network)];
        }

        $start = $mask === 31 ? $network : $network + 1;
        $end = $mask === 31 ? $network + 1 : $network + $hostCount - 2;

        $ips = [];
        for ($ip = $start; $ip <= $end; $ip++) {
            $ips[] = long2ip($ip);
        }

        return $ips;
    }

    private function resolveHostname(string $ip): ?string
    {
        $hostname = @gethostbyaddr($ip);
        return ($hostname !== false && $hostname !== $ip) ? $hostname : null;
    }
}