const express = require('express');
const crypto = require('crypto');
const authMiddleware = require('../middleware/auth');
const {
  DesktopSessionError,
  createDesktopSession,
  createSsoTicket,
  exchangeSsoTicket,
  getDesktopBootstrap,
  revokeDesktopSession,
} = require('../services/desktopSessionService');

const router = express.Router();

function requestUserId(req) {
  return req.user?.sub ?? req.user?.id;
}

function sendDesktopSessionError(res, error, fallbackMessage) {
  if (error instanceof DesktopSessionError) {
    return res.status(error.status).json({
      success: false,
      error: error.message,
      code: error.code,
    });
  }
  console.error(fallbackMessage, error);
  return res.status(500).json({ success: false, error: fallbackMessage });
}

function safeScriptJson(value) {
  return JSON.stringify(value)
    .replace(/</g, '\\u003c')
    .replace(/>/g, '\\u003e')
    .replace(/&/g, '\\u0026')
    .replace(/\u2028/g, '\\u2028')
    .replace(/\u2029/g, '\\u2029');
}

function sendSsoExchangeHtml(res, result) {
  const nonce = crypto.randomBytes(18).toString('base64');
  res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate, private');
  res.setHeader('Pragma', 'no-cache');
  res.setHeader('Referrer-Policy', 'no-referrer');
  res.setHeader('X-Content-Type-Options', 'nosniff');
  res.setHeader(
    'Content-Security-Policy',
    `default-src 'none'; script-src 'nonce-${nonce}'; style-src 'nonce-${nonce}'; base-uri 'none'; form-action 'none'; frame-ancestors 'self'`
  );
  res.type('html').send(`<!doctype html>
<html lang="zh-CN">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width,initial-scale=1">
  <title>正在进入总控</title>
  <style nonce="${nonce}">html,body{height:100%;margin:0;background:#f7f8fa;color:#8c8c8c;font:14px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}body{display:grid;place-items:center}</style>
</head>
<body><span>正在进入总控...</span>
<script nonce="${nonce}">
try {
  localStorage.setItem('token', ${safeScriptJson(result.accessToken)});
  localStorage.setItem('auth_user', JSON.stringify(${safeScriptJson(result.user)}));
  sessionStorage.setItem('desktop_embed', '1');
  location.replace(${safeScriptJson(result.redirectPath)});
} catch (error) {
  document.body.textContent = '总控登录状态写入失败，请返回桌面客户端重试';
}
</script></body></html>`);
}

router.post('/session', authMiddleware, async (req, res) => {
  try {
    if (req.user?.tokenType) {
      throw new DesktopSessionError('请使用用户登录令牌创建桌面会话', 401, 'DESKTOP_USER_TOKEN_REQUIRED');
    }
    const data = await createDesktopSession({
      userId: requestUserId(req),
      payload: req.body || {},
    });
    res.setHeader('Cache-Control', 'no-store');
    return res.json({ success: true, data });
  } catch (error) {
    return sendDesktopSessionError(res, error, '创建桌面会话失败');
  }
});

router.get('/bootstrap', authMiddleware, async (req, res) => {
  try {
    const data = await getDesktopBootstrap({
      claims: req.user,
      clientId: req.query.clientId,
    });
    res.setHeader('Cache-Control', 'no-store');
    return res.json({ success: true, data });
  } catch (error) {
    return sendDesktopSessionError(res, error, '读取桌面启动配置失败');
  }
});

router.post('/sso-ticket', authMiddleware, async (req, res) => {
  try {
    const data = await createSsoTicket({
      claims: req.user,
      clientId: req.body?.clientId,
      redirectPath: req.body?.redirectPath,
    });
    res.setHeader('Cache-Control', 'no-store');
    return res.json({ success: true, data });
  } catch (error) {
    return sendDesktopSessionError(res, error, '创建总控登录票据失败');
  }
});

router.get('/sso/exchange', async (req, res) => {
  try {
    const result = await exchangeSsoTicket(req.query.ticket);
    return sendSsoExchangeHtml(res, result);
  } catch (error) {
    if (error instanceof DesktopSessionError) {
      res.setHeader('Cache-Control', 'no-store');
      return res.status(error.status).type('html').send('<!doctype html><meta charset="utf-8"><title>登录失效</title><body>登录票据无效或已过期，请返回桌面客户端重试。</body>');
    }
    console.error('交换总控登录票据失败', error);
    return res.status(500).type('html').send('<!doctype html><meta charset="utf-8"><title>登录失败</title><body>总控登录失败，请稍后重试。</body>');
  }
});

router.post('/session/revoke', authMiddleware, async (req, res) => {
  try {
    const data = await revokeDesktopSession(req.user);
    res.setHeader('Cache-Control', 'no-store');
    return res.json({ success: true, data });
  } catch (error) {
    return sendDesktopSessionError(res, error, '退出桌面会话失败');
  }
});

module.exports = router;