import { Router } from 'express';
import { config, isAllowedUrl } from '../config.js';
import { buildLoginUrl, buildLogoutUrl, handleCallback } from '../oidc.js';

export const authRouter = Router();

/** Rücksprung nur auf das Portal selbst oder erlaubte Tool-Domains. */
function safeReturnTo(raw: unknown): string {
  if (typeof raw !== 'string' || !raw) return '/';
  if (raw.startsWith('/') && !raw.startsWith('//')) return raw;
  return isAllowedUrl(raw) ? raw : '/';
}

authRouter.get('/login', async (req, res, next) => {
  try {
    const returnTo = safeReturnTo(req.query.returnTo);
    if (config.devUser) {
      req.session.user = {
        sub: `dev-${config.devUser}`,
        username: config.devUser,
        name: config.devUser.charAt(0).toUpperCase() + config.devUser.slice(1),
        email: `${config.devUser}@example.invalid`,
        groups: ['HI-Mitarbeiter', 'HI-Admin'],
      };
      return res.redirect(returnTo);
    }
    const { url, state, codeVerifier } = await buildLoginUrl();
    req.session.login = { state, codeVerifier, returnTo };
    req.session.save((err) => (err ? next(err) : res.redirect(url)));
  } catch (err) {
    next(err);
  }
});

authRouter.get('/callback', async (req, res) => {
  const pending = req.session.login;
  if (!pending) return res.redirect('/auth/login');
  try {
    const query = req.originalUrl.slice(req.originalUrl.indexOf('?'));
    const { user, idToken } = await handleCallback(query, pending);
    const returnTo = pending.returnTo;
    // Neue Session-ID nach dem Login (Schutz vor Session Fixation).
    req.session.regenerate((err) => {
      if (err) return res.status(500).send('Anmeldung fehlgeschlagen.');
      req.session.user = user;
      req.session.idToken = idToken;
      req.session.save(() => res.redirect(returnTo));
    });
  } catch (err) {
    console.error('[auth] Callback fehlgeschlagen:', err);
    delete req.session.login;
    res.status(401).send('Anmeldung fehlgeschlagen. <a href="/auth/login">Erneut versuchen</a>');
  }
});

authRouter.get('/logout', async (req, res, next) => {
  try {
    const url = await buildLogoutUrl(req.session.idToken);
    req.session.destroy(() => {
      res.clearCookie('hi.portal.sid');
      res.redirect(url);
    });
  } catch (err) {
    next(err);
  }
});