<?php
require_once __DIR__ . '/../utils/Config.php';
require_once __DIR__ . '/../utils/Logger.php';
require_once __DIR__ . '/SmtpHandler.php';
class SmtpServer {
    private $host;
    private $port;
    private $maxConnections;
    private $socket;
    private $connections = [];
    private $logger;
    private $config;
    public function __construct($host = '0.0.0.0', $port = 25, $maxConnections = 100) {
        $this->config = Config::getInstance();
        $this->host = $host;
        $this->port = $port;
        $this->maxConnections = $maxConnections;
        $logPath = $this->config->get('log.path', '../logs/');
        $logLevel = $this->config->get('log.level', 'info');
        $this->logger = new Logger($logPath, $logLevel);
    }
    public function start() {
        $this->socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
        if ($this->socket === false) { $this->logger->error("Failed to create socket: " . socket_strerror(socket_last_error())); return false; }
        socket_set_option($this->socket, SOL_SOCKET, SO_REUSEADDR, 1);
        if (!socket_bind($this->socket, $this->host, $this->port)) { $this->logger->error("Failed to bind socket: " . socket_strerror(socket_last_error($this->socket))); socket_close($this->socket); return false; }
        $backlog = $this->config->get('smtp.backlog', 50);
        if (!socket_listen($this->socket, $backlog)) { $this->logger->error("Failed to listen on socket: " . socket_strerror(socket_last_error($this->socket))); socket_close($this->socket); return false; }
        $this->logger->info("SMTP server started on {host}:{port}", ['host' => $this->host, 'port' => $this->port]);
        while (true) { $this->handleConnections(); }
        return true;
    }
    public function stop() {
        foreach ($this->connections as $connection) { socket_close($connection['socket']); }
        if ($this->socket) { socket_close($this->socket); }
        $this->logger->info("SMTP server stopped");
    }
    private function handleConnections() {
        $readSockets = array_column($this->connections, 'socket');
        $readSockets[] = $this->socket;
        $writeSockets = null;
        $exceptSockets = null;
        $activity = socket_select($readSockets, $writeSockets, $exceptSockets, 1);
        if ($activity === false) { $this->logger->error("Socket select error: " . socket_strerror(socket_last_error())); return; }
        foreach ($readSockets as $socket) {
            if ($socket === $this->socket) { $this->acceptNewConnection(); } else { $this->handleClientRequest($socket); }
        }
        $this->cleanupTimeoutConnections();
    }
    private function acceptNewConnection() {
        if (count($this->connections) >= $this->maxConnections) { $this->logger->warning("Maximum connections reached: {max}", ['max' => $this->maxConnections]); return; }
        $clientSocket = socket_accept($this->socket);
        if ($clientSocket === false) { $this->logger->error("Failed to accept connection: " . socket_strerror(socket_last_error($this->socket))); return; }
        socket_getpeername($clientSocket, $clientIp, $clientPort);
        $this->logger->info("New connection from {ip}:{port}", ['ip' => $clientIp, 'port' => $clientPort]);
        $connectionId = uniqid();
        $socketKey = (int)$clientSocket;
        $this->connections[$connectionId] = [
            'socket' => $clientSocket,
            'ip' => $clientIp,
            'port' => $clientPort,
            'handler' => new SmtpHandler($clientSocket, $clientIp, $this->logger),
            'lastActivity' => time()
        ];
        static $socketToConnection = [];
        $socketToConnection[$socketKey] = $connectionId;
        $welcomeMsg = "220 {domain} ESMTP Service Ready\r\n";
        socket_write($clientSocket, $welcomeMsg, strlen($welcomeMsg));
    }
    private function handleClientRequest($socket) {
        $socketKey = (int)$socket;
        static $socketToConnection = [];
        if (empty($socketToConnection) && !empty($this->connections)) {
            foreach ($this->connections as $id => $connection) { $socketToConnection[(int)$connection['socket']] = $id; }
        }
        if (!isset($socketToConnection[$socketKey])) {
            $socketToConnection = [];
            foreach ($this->connections as $id => $connection) { $socketToConnection[(int)$connection['socket']] = $id; }
            if (!isset($socketToConnection[$socketKey])) { return; }
        }
        $connectionId = $socketToConnection[$socketKey];
        $data = socket_read($socket, 1024);
        if ($data === false) { $this->logger->error("Failed to read from socket: " . socket_strerror(socket_last_error($socket))); $this->closeConnection($connectionId); return; }
        if (empty($data)) { $this->logger->info("Connection closed by client: {ip}:{port}", ['ip' => $this->connections[$connectionId]['ip'], 'port' => $this->connections[$connectionId]['port']]); $this->closeConnection($connectionId); return; }
        $this->connections[$connectionId]['lastActivity'] = time();
        $this->connections[$connectionId]['handler']->handle($data);
    }
    private function closeConnection($connectionId) {
        if (isset($this->connections[$connectionId])) {
            $socket = $this->connections[$connectionId]['socket'];
            $socketKey = (int)$socket;
            static $socketToConnection = [];
            if (isset($socketToConnection[$socketKey])) { unset($socketToConnection[$socketKey]); }
            socket_close($socket);
            unset($this->connections[$connectionId]);
        }
    }
    private function cleanupTimeoutConnections() {
        $timeout = 300;
        $now = time();
        foreach ($this->connections as $id => $connection) {
            if ($now - $connection['lastActivity'] > $timeout) {
                $this->logger->info("Connection timed out: {ip}:{port}", ['ip' => $connection['ip'], 'port' => $connection['port']]);
                $this->closeConnection($id);
            }
        }
    }
}