function assertRouter(api) {
  if (!api || typeof api.get !== 'function') {
    throw new Error('attachPortalPlazaDiscoveryRoutes requires an Express-compatible router');
  }
}

function defaultSendData(res, _req, data) {
  return res.json(data);
}

function defaultSendError(res, _req, status, code, message) {
  return res.status(status).json({ error: { code, message } });
}

function defaultRouteError(_res, _req, error) {
  throw error;
}

export function attachPortalPlazaDiscoveryRoutes(
  api,
  {
    getPlazaPosts = () => null,
    getPlazaSeo = () => null,
    sendData = defaultSendData,
    sendError = defaultSendError,
    handleRouteError = defaultRouteError,
  } = {},
) {
  assertRouter(api);

  api.get('/plaza/v1/categories', async (req, res) => {
    const plazaPosts = getPlazaPosts();
    if (!plazaPosts) {
      sendError(res, req, 503, 'plaza_unavailable', 'Plaza 未启用');
      return;
    }
    try {
      return sendData(res, req, { categories: await plazaPosts.listCategories() });
    } catch (error) {
      return handleRouteError(res, req, error);
    }
  });

  api.get('/plaza/v1/seo/sitemap', async (req, res) => {
    const plazaPosts = getPlazaPosts();
    if (!plazaPosts) {
      sendError(res, req, 503, 'plaza_unavailable', 'Plaza 未启用');
      return;
    }
    const plazaSeo = getPlazaSeo();
    if (!plazaSeo) {
      return sendError(res, req, 503, 'plaza_unavailable', 'Plaza SEO 未启用');
    }
    try {
      const data = await plazaSeo.listSitemapData({
        postLimit: req.query.post_limit,
        userLimit: req.query.user_limit,
      });
      return sendData(res, req, data);
    } catch (error) {
      return handleRouteError(res, req, error);
    }
  });
}