<?php
/**
 * Wysyłka emaili przez SMTP z obsługą STARTTLS (port 587) i SSL (port 465)
 */
function sendEmailSMTP($to, $subject, $html_body, $config = null) {
    $log_file = __DIR__ . '/smtp_debug.log';
    file_put_contents($log_file, date('Y-m-d H:i:s') . " - Function called for: $to\n", FILE_APPEND);

    if ($config === null) {
        $config = require __DIR__ . '/smtp_config.php';
    }

    $log   = [];
    $log[] = date('Y-m-d H:i:s') . " - Starting SMTP to: $to";

    $encryption = strtolower($config['encryption'] ?? 'tls');
    $host       = $config['host'];
    $port       = (int)$config['port'];

    // Funkcja odczytu pełnej odpowiedzi SMTP (wieloliniowej)
    $read = function($sock) {
        $out = '';
        while ($line = fgets($sock, 515)) {
            $out .= $line;
            if (preg_match('/^\d{3} /', $line)) break;
        }
        return $out;
    };

    if ($encryption === 'ssl') {
        $ctx  = stream_context_create(['ssl' => ['verify_peer' => false, 'verify_peer_name' => false]]);
        $sock = @stream_socket_client("ssl://{$host}:{$port}", $errno, $errstr, 30, STREAM_CLIENT_CONNECT, $ctx);
    } else {
        // TLS/STARTTLS — najpierw plain socket, potem STARTTLS
        $sock = @stream_socket_client("tcp://{$host}:{$port}", $errno, $errstr, 30);
    }

    if (!$sock) {
        $log[] = "Connection FAILED: $errstr ($errno)";
        file_put_contents($log_file, implode("\n", $log) . "\n\n", FILE_APPEND);
        return false;
    }

    stream_set_timeout($sock, 30);
    $log[] = "Connected to {$host}:{$port} ({$encryption})";

    $resp  = $read($sock);
    $log[] = "Server: " . trim($resp);

    fwrite($sock, "EHLO {$host}\r\n");
    $resp  = $read($sock);
    $log[] = "EHLO: " . trim($resp);

    // STARTTLS dla TLS/port 587
    if ($encryption === 'tls') {
        fwrite($sock, "STARTTLS\r\n");
        $resp  = $read($sock);
        $log[] = "STARTTLS: " . trim($resp);

        if (strpos($resp, '220') === false) {
            $log[] = "STARTTLS not accepted";
            file_put_contents($log_file, implode("\n", $log) . "\n\n", FILE_APPEND);
            fclose($sock);
            return false;
        }

        // Upgrade do TLS
        $ctx = stream_context_create(['ssl' => ['verify_peer' => false, 'verify_peer_name' => false]]);
        if (!stream_socket_enable_crypto($sock, true, STREAM_CRYPTO_METHOD_TLS_CLIENT)) {
            $log[] = "TLS upgrade FAILED";
            file_put_contents($log_file, implode("\n", $log) . "\n\n", FILE_APPEND);
            fclose($sock);
            return false;
        }

        $log[] = "TLS upgraded OK";

        // EHLO ponownie po TLS
        fwrite($sock, "EHLO {$host}\r\n");
        $resp  = $read($sock);
        $log[] = "EHLO2: " . trim($resp);
    }

    fwrite($sock, "AUTH LOGIN\r\n");
    $resp  = $read($sock);
    $log[] = "AUTH: " . trim($resp);

    fwrite($sock, base64_encode($config['username']) . "\r\n");
    $resp  = $read($sock);
    $log[] = "USER: " . trim($resp);

    fwrite($sock, base64_encode($config['password']) . "\r\n");
    $resp  = $read($sock);
    $log[] = "PASS: " . trim($resp);

    if (strpos($resp, '235') === false) {
        $log[] = "Auth FAILED";
        file_put_contents($log_file, implode("\n", $log) . "\n\n", FILE_APPEND);
        fclose($sock);
        return false;
    }

    // MAIL FROM
    fwrite($sock, "MAIL FROM: <{$config['from_email']}>\r\n");
    $resp  = $read($sock);
    $log[] = "FROM: " . trim($resp);

    // RCPT TO
    fwrite($sock, "RCPT TO: <{$to}>\r\n");
    $resp  = $read($sock);
    $log[] = "TO: " . trim($resp);

    // DATA
    fwrite($sock, "DATA\r\n");
    $resp  = $read($sock);
    $log[] = "DATA: " . trim($resp);

    $msgId   = '<' . time() . '.' . rand(1000, 9999) . '@' . $host . '>';
    $headers  = "From: {$config['from_name']} <{$config['from_email']}>\r\n";
    $headers .= "To: <{$to}>\r\n";
    $headers .= "Subject: =?UTF-8?B?" . base64_encode($subject) . "?=\r\n";
    $headers .= "Message-ID: {$msgId}\r\n";
    $headers .= "Date: " . date('r') . "\r\n";
    $headers .= "MIME-Version: 1.0\r\n";
    $headers .= "Content-Type: text/html; charset=UTF-8\r\n";
    $headers .= "\r\n";

    fwrite($sock, $headers . $html_body . "\r\n.\r\n");
    $resp  = $read($sock);
    $log[] = "SEND: " . trim($resp);

    fwrite($sock, "QUIT\r\n");
    $resp  = $read($sock);
    $log[] = "QUIT: " . trim($resp);

    fclose($sock);

    $success = strpos($log[count($log) - 2], '250') !== false;
    $log[]   = "Result: " . ($success ? "SUCCESS" : "FAILED");
    file_put_contents($log_file, implode("\n", $log) . "\n\n", FILE_APPEND);

    return $success;
}