<?php

declare(strict_types=1);

namespace Domovoy\Services\Discovery;

class TcpPortScanner
{
    /**
     * Scan a list of TCP ports on a host.
     *
     * @param int[] $ports
     * @param int $timeoutMs connection timeout per port
     * @param int $maxConcurrency max parallel connections
     * @return int[] list of open ports
     */
    public function scan(string $ip, array $ports, int $timeoutMs = 200, int $maxConcurrency = 50): array
    {
        $openPorts = [];
        $timeoutSec = $timeoutMs / 1000;

        if (function_exists('curl_multi_init')) {
            // Parallel scan with curl_multi
            $chunks = array_chunk($ports, $maxConcurrency);
            foreach ($chunks as $chunk) {
                $multiHandle = curl_multi_init();
                $handles = [];
                foreach ($chunk as $port) {
                    $ch = curl_init();
                    curl_setopt($ch, CURLOPT_URL, "http://{$ip}:{$port}");
                    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
                    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT_MS, $timeoutMs);
                    curl_setopt($ch, CURLOPT_TIMEOUT_MS, $timeoutMs);
                    curl_setopt($ch, CURLOPT_NOBODY, true);
                    curl_multi_add_handle($multiHandle, $ch);
                    $handles[$port] = $ch;
                }

                // Execute
                $running = null;
                do {
                    curl_multi_exec($multiHandle, $running);
                    curl_multi_select($multiHandle, 0.1);
                } while ($running > 0);

                // Check results
                foreach ($handles as $port => $ch) {
                    $err = curl_errno($ch);
                    // CURLE_COULDNT_CONNECT (7) = port closed, others might mean open or filtered
                    if ($err !== CURLE_COULDNT_CONNECT) {
                        $openPorts[] = $port;
                    }
                    curl_multi_remove_handle($multiHandle, $ch);
                    curl_close($ch);
                }

                curl_multi_close($multiHandle);
            }
        } else {
            // Sequential fallback
            foreach ($ports as $port) {
                $fp = @fsockopen($ip, $port, $errno, $errstr, $timeoutSec);
                if ($fp !== false) {
                    $openPorts[] = $port;
                    fclose($fp);
                }
            }
        }

        sort($openPorts);
        return $openPorts;
    }
}