const nodemailer = require('nodemailer');
const { getPool, query, getRow, getConfig } = require('./db');
const { logEmail, logSystem } = require('./logger');

async function getSmtpConfig() {
  try {
    const rows = await query("SELECT k, v FROM settings WHERE k LIKE 'smtp_%'");
    const cfg = {};
    for (const r of rows) cfg[r.k] = r.v;
    return {
      host: cfg.smtp_host || '',
      port: parseInt(cfg.smtp_port) || 587,
      secure: cfg.smtp_secure === '1',
      user: cfg.smtp_user || '',
      pass: cfg.smtp_pass || '',
      from: cfg.smtp_from || 'noreply@example.com',
    };
  } catch { return { host: '', port: 587, secure: false, user: '', pass: '', from: '' }; }
}

async function getSiteName() {
  const row = await getRow("SELECT v FROM settings WHERE k = 'site_name'");
  return row ? row.v : 'MC举报系统';
}

async function getSiteUrl() {
  const row = await getRow("SELECT v FROM settings WHERE k = 'site_url'");
  return row ? row.v : 'http://localhost:3100';
}

async function getTemplate(code) {
  return getRow('SELECT * FROM email_templates WHERE code = ?', [code]);
}

function renderTemplate(template, vars) {
  let { subject, body } = template;
  for (const [k, v] of Object.entries(vars)) {
    const re = new RegExp(`\\{\\{${k}\\}\\}`, 'g');
    const val = String(v ?? '');
    subject = subject.replace(re, () => val);
    body = body.replace(re, () => val);
  }
  return { subject, body };
}

let _transporter = null;
let _transporterKey = '';

function getTransporter(cfg) {
  const key = `${cfg.host}:${cfg.port}:${cfg.user}`;
  if (_transporter && _transporterKey === key) return _transporter;
  _transporterKey = key;
  _transporter = nodemailer.createTransport({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: { user: cfg.user, pass: cfg.pass } });
  return _transporter;
}

async function sendEmail(to, templateCode, vars) {
  try {
    const cfg = await getSmtpConfig();
    if (!cfg.host || !cfg.user) { console.log('[Mailer] SMTP未配置'); await logSystem('warn', 'mailer', 'SMTP未配置，邮件未发送', { to, template: templateCode }); return false; }
    const template = await getTemplate(templateCode);
    if (!template) { console.log('[Mailer] 模板不存在:', templateCode); await logEmail(to, templateCode, '', 'failed', '模板不存在: ' + templateCode); return false; }
    const siteName = await getSiteName();
    const allVars = { ...vars, site_name: siteName, site_url: await getSiteUrl() };
    const { subject, body } = renderTemplate(template, allVars);
    const transporter = getTransporter(cfg);
    await transporter.sendMail({ from: `"${siteName}" <${cfg.from}>`, to, subject, html: body });
    await logEmail(to, templateCode, subject, 'sent');
    return true;
  } catch (err) {
    console.error('[Mailer]', err.message);
    await logEmail(to, templateCode, '', 'failed', err.message);
    return false;
  }
}

module.exports = { sendEmail, renderTemplate, getTemplate, getSmtpConfig, getSiteName, getSiteUrl };