function dbConfig(key: string): string {
  try {
    const { getDb } = require('./db');
    const row = getDb().query('SELECT value FROM content WHERE key = ?').get(key) as { value: string } | null;
    return row?.value || '';
  } catch { return ''; }
}

function cfg(): { host: string; port: number; user: string; pass: string; from: string } {
  return {
    host: dbConfig('smtp_host') || process.env.SMTP_HOST || '',
    port: parseInt(dbConfig('smtp_port') || process.env.SMTP_PORT || '587'),
    user: dbConfig('smtp_user') || process.env.SMTP_USER || '',
    pass: dbConfig('smtp_pass') || process.env.SMTP_PASS || '',
    from: dbConfig('smtp_from') || process.env.MAIL_FROM || 'shop@zlattea.com',
  };
}

function enabled(): boolean {
  const c = cfg();
  return !!(c.host && c.port && c.user && c.pass);
}

// minimal text/plain email via direct SMTP/TLS. for production, consider an
// external transactional mail api. this path is acceptable for local dev until
// volume requires more.
export async function sendMail(to: string, subject: string, body: string) {
  if (!enabled()) { console.log('email skipped (no SMTP config):', subject, to); return; }
  const c = cfg();
  const conn = await require('node:tls').connect({ host: c.host, port: c.port, servername: c.host });
  const send = (s: string) => conn.write(s + '\r\n');
  let buf = '';
  const readUntil = (code: number, timeoutMs = 10000): Promise<string> => new Promise((resolve, reject) => {
    const t = setTimeout(() => reject(new Error('smtp timeout')), timeoutMs);
    const onData = (d: Buffer) => {
      buf += d.toString();
      if (buf.includes('\r\n')) {
        const lines = buf.split('\r\n');
        const last = lines[lines.length - 2] || '';
        if (last.startsWith(String(code)) || last.startsWith(String(code) + ' ')) {
          clearTimeout(t);
          conn.off('data', onData);
          resolve(last);
        }
      }
    };
    conn.on('data', onData);
  });
  await readUntil(220);
  send(`EHLO ${c.host}`);
  await readUntil(250);
  send('AUTH LOGIN');
  await readUntil(334);
  send(Buffer.from(c.user).toString('base64'));
  await readUntil(334);
  send(Buffer.from(c.pass).toString('base64'));
  await readUntil(235);
  send(`MAIL FROM:<${c.from}>`);
  await readUntil(250);
  send(`RCPT TO:<${to}>`);
  await readUntil(250);
  send('DATA');
  await readUntil(354);
  const msg = [
    `From: Zlattea <${c.from}>`,
    `To: ${to}`,
    `Subject: =?UTF-8?B?${Buffer.from(subject).toString('base64')}?=`,
    'Content-Type: text/plain; charset=utf-8',
    '',
    body,
    '.',
  ].join('\r\n');
  send(msg);
  await readUntil(250);
  send('QUIT');
  conn.end();
}

export function orderCreatedEmail(to: string, orderId: string, viewToken: string, totalLv: string, itemsDesc: string) {
  if (!enabled()) return;
  const url = `${process.env.SITE_URL || 'http://localhost:3000'}/order/${orderId}?t=${viewToken}`;
  sendMail(to, `Поръчка ${orderId.slice(0, 8)} - Златен чай`,
    `Благодарим за поръчката! Вашият номер на поръчка: ${orderId.slice(0, 8)}\n\n` +
    `Продукти:\n${itemsDesc}\n\nОбщо: ${totalLv}\n\n` +
    `Следете статуса тук: ${url}\n\n` +
    `Ако сте избрали банков превод или плащане с Lightning/Bitcoin, ще получите допълнителни инструкции на тази страница.\n\n` +
    `Златен чай`);
}

export function paymentConfirmedEmail(to: string, orderId: string) {
  if (!enabled()) return;
  sendMail(to, `Плащането е получено - Поръчка ${orderId.slice(0, 8)}`,
    `Плащането за поръчка ${orderId.slice(0, 8)} е получено. Ще ви известим при изпращане.\n\nЗлатен чай`);
}