<?php
/**
 * Yksinkertainen SMTP-lähetys ilman ulkoisia kirjastoja.
 * Tukee STARTTLS + AUTH LOGIN.
 */
function smtp_send($to, $subject, $body, $replyTo = '') {
    require_once __DIR__ . '/config.php';

    $host = SMTP_HOST;
    $port = SMTP_PORT;
    $user = SMTP_USER;
    $pass = SMTP_PASS;
    $from = SMTP_FROM;
    $fromName = defined('SMTP_FROM_NAME') ? SMTP_FROM_NAME : '';

    $errors = [];

    // Connect
    $socket = @fsockopen($host, $port, $errno, $errstr, 10);
    if (!$socket) {
        return ['ok' => false, 'error' => "Connection failed: $errstr ($errno)"];
    }

    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '220') {
        fclose($socket);
        return ['ok' => false, 'error' => "Server greeting failed: $resp"];
    }

    // EHLO
    fwrite($socket, "EHLO konesaliturku.fi\r\n");
    $resp = '';
    while ($line = fgets($socket, 512)) {
        $resp .= $line;
        if ($line[3] === ' ') break;
    }

    // STARTTLS
    fwrite($socket, "STARTTLS\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '220') {
        fclose($socket);
        return ['ok' => false, 'error' => "STARTTLS failed: $resp"];
    }

    // Enable TLS
    $crypto = stream_socket_enable_crypto($socket, true, STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT | STREAM_CRYPTO_METHOD_TLSv1_3_CLIENT);
    if (!$crypto) {
        fclose($socket);
        return ['ok' => false, 'error' => "TLS handshake failed"];
    }

    // EHLO again after TLS
    fwrite($socket, "EHLO konesaliturku.fi\r\n");
    $resp = '';
    while ($line = fgets($socket, 512)) {
        $resp .= $line;
        if ($line[3] === ' ') break;
    }

    // AUTH LOGIN
    fwrite($socket, "AUTH LOGIN\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '334') {
        fclose($socket);
        return ['ok' => false, 'error' => "AUTH failed: $resp"];
    }

    fwrite($socket, base64_encode($user) . "\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '334') {
        fclose($socket);
        return ['ok' => false, 'error' => "AUTH user failed: $resp"];
    }

    fwrite($socket, base64_encode($pass) . "\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '235') {
        fclose($socket);
        return ['ok' => false, 'error' => "AUTH password failed: $resp"];
    }

    // MAIL FROM
    fwrite($socket, "MAIL FROM:<$from>\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '250') {
        fclose($socket);
        return ['ok' => false, 'error' => "MAIL FROM failed: $resp"];
    }

    // RCPT TO
    fwrite($socket, "RCPT TO:<$to>\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '250') {
        fclose($socket);
        return ['ok' => false, 'error' => "RCPT TO failed: $resp"];
    }

    // DATA
    fwrite($socket, "DATA\r\n");
    $resp = fgets($socket, 512);
    if (substr($resp, 0, 3) !== '354') {
        fclose($socket);
        return ['ok' => false, 'error' => "DATA failed: $resp"];
    }

    // Build message
    $fromHeader = $fromName ? "\"$fromName\" <$from>" : $from;
    $msg = "From: $fromHeader\r\n";
    $msg .= "To: $to\r\n";
    $msg .= "Subject: =?UTF-8?B?" . base64_encode($subject) . "?=\r\n";
    if ($replyTo) {
        $msg .= "Reply-To: $replyTo\r\n";
    }
    $msg .= "MIME-Version: 1.0\r\n";
    $msg .= "Content-Type: text/plain; charset=UTF-8\r\n";
    $msg .= "Content-Transfer-Encoding: 8bit\r\n";
    $msg .= "Date: " . date('r') . "\r\n";
    $msg .= "\r\n";
    $msg .= $body;
    $msg .= "\r\n.\r\n";

    fwrite($socket, $msg);
    $resp = fgets($socket, 512);

    // QUIT
    fwrite($socket, "QUIT\r\n");
    fclose($socket);

    if (substr($resp, 0, 3) === '250') {
        return ['ok' => true];
    }

    return ['ok' => false, 'error' => "Send failed: $resp"];
}