<?php
require_once __DIR__ . '/../utils/Config.php';
class Pop3Handler {
    private $socket;
    private $clientIp;
    private $logger;
    private $config;
    private $state = 'auth';
    private $username = '';
    private $password = '';
    private $authenticated = false;
    private $messages = [];
    private $deletedMessages = [];
    private $messageCount = 0;
    private $mailboxSize = 0;
    public function __construct($socket, $clientIp, $logger) {
        $this->socket = $socket;
        $this->clientIp = $clientIp;
        $this->logger = $logger;
        $this->config = Config::getInstance();
    }
    public function handle($data) {
        $lines = explode("\r\n", $data);
        foreach ($lines as $line) {
            $line = trim($line);
            if ($line === '') { continue; }
            $this->processCommand($line);
        }
    }
    private function processCommand($line) {
        $parts = preg_split('/\\s+/', $line, 2);
        $cmd = strtoupper($parts[0]);
        $arg = $parts[1] ?? '';
        switch ($cmd) {
            case 'USER':
                $this->username = $arg;
                $this->send("+OK");
                break;
            case 'PASS':
                $this->password = $arg;
                if ($this->authenticate()) {
                    $this->authenticated = true;
                    $this->state = 'transaction';
                    $this->initMessages($this->username);
                    $this->send("+OK {$this->messageCount} {$this->mailboxSize}");
                } else {
                    $this->send("-ERR");
                }
                break;
            case 'STAT':
                if (!$this->authenticated) { $this->send("-ERR"); break; }
                $this->send("+OK {$this->messageCount} {$this->mailboxSize}");
                break;
            case 'LIST':
                if (!$this->authenticated) { $this->send("-ERR"); break; }
                if (!empty($arg)) {
                    $id = (int)$arg;
                    if (isset($this->messages[$id])) { $this->send("+OK {$id} {$this->messages[$id]['size']}"); }
                    else { $this->send("-ERR"); }
                } else {
                    $this->send("+OK {$this->messageCount} messages");
                    foreach ($this->messages as $id => $msg) { $this->send("{$id} {$msg['size']}"); }
                    $this->send(".");
                }
                break;
            case 'UIDL':
                if (!$this->authenticated) { $this->send("-ERR"); break; }
                if (!empty($arg)) {
                    $id = (int)$arg;
                    if (isset($this->messages[$id])) { $this->send("+OK {$id} {$this->messages[$id]['uid']}"); }
                    else { $this->send("-ERR"); }
                } else {
                    $this->send("+OK");
                    foreach ($this->messages as $id => $msg) { $this->send("{$id} {$msg['uid']}"); }
                    $this->send(".");
                }
                break;
            case 'RETR':
                if (!$this->authenticated) { $this->send("-ERR"); break; }
                $id = (int)$arg;
                if (isset($this->messages[$id])) {
                    $this->send("+OK {$this->messages[$id]['size']} octets");
                    $this->sendRaw($this->messages[$id]['content']);
                    $this->send(".");
                } else { $this->send("-ERR"); }
                break;
            case 'DELE':
                if (!$this->authenticated) { $this->send("-ERR"); break; }
                $id = (int)$arg;
                if (isset($this->messages[$id])) { $this->deletedMessages[$id] = true; $this->send("+OK"); }
                else { $this->send("-ERR"); }
                break;
            case 'NOOP':
                $this->send("+OK");
                break;
            case 'RSET':
                $this->deletedMessages = [];
                $this->send("+OK");
                break;
            case 'QUIT':
                if ($this->authenticated) { $this->applyDeletes(); }
                $this->send("+OK bye");
                break;
            default:
                $this->send("-ERR");
                break;
        }
    }
    private function authenticate() {
        try {
            require_once __DIR__ . '/../utils/Database.php';
            $db = Database::getInstance();
            $row = $db->fetchOne("SELECT password FROM user WHERE username = ? AND is_deleted = 0", [$this->username]);
            if (!$row) { return false; }
            return password_verify($this->password, $row['password']);
        } catch (Exception $e) {
            return false;
        }
    }
    private function initMessages($username) {
        try {
            require_once __DIR__ . '/../utils/Database.php';
            $db = Database::getInstance();
            $emails = $db->fetchAll("SELECT * FROM email WHERE rcpt_to = ? AND folder = 'inbox' AND is_deleted = 0 ORDER BY `date` ASC", [$username]);
            $this->messages = [];
            $this->messageCount = 0;
            $this->mailboxSize = 0;
            $this->deletedMessages = [];
            if ($emails) {
                $id = 1;
                foreach ($emails as $email) {
                    $content = "From: {$email['from']}\r\n" .
                               "To: {$email['to']}\r\n" .
                               "Subject: {$email['subject']}\r\n" .
                               "Date: {$email['date']}\r\n\r\n" .
                               "{$email['data']}\r\n";
                    $size = strlen($content);
                    $this->messages[$id] = [
                        'uid' => $email['id'],
                        'size' => $size,
                        'content' => $content,
                        'email_id' => $email['id']
                    ];
                    $this->mailboxSize += $size;
                    $id++;
                }
            }
            $this->messageCount = count($this->messages);
        } catch (Exception $e) {
            $this->messages = [];
            $this->messageCount = 0;
            $this->mailboxSize = 0;
            $this->deletedMessages = [];
        }
    }
    private function applyDeletes() {
        if (empty($this->deletedMessages)) { return; }
        try {
            require_once __DIR__ . '/../utils/Database.php';
            $db = Database::getInstance();
            foreach ($this->deletedMessages as $id => $_) {
                if (isset($this->messages[$id])) {
                    $db->update("UPDATE email SET is_deleted = 1, folder = 'trash' WHERE id = ?", [$this->messages[$id]['email_id']]);
                }
            }
        } catch (Exception $e) {}
    }
    private function send($line) { $out = $line . "\r\n"; socket_write($this->socket, $out, strlen($out)); }
    private function sendRaw($raw) { socket_write($this->socket, $raw, strlen($raw)); }
}