import express from 'express';
import bcrypt from 'bcryptjs';
import crypto from 'node:crypto';
import { pool } from '../db.js';
import { publicUser, requireAuth, signShort, signToken, verifyShort } from '../middleware/auth.js';
import { getSettings } from '../lib/settings.js';
import { authorizeUrl, exchangeCode, ssoConfigured } from '../lib/sso.js';
import { normalizeAvatar } from '../lib/avatar.js';

const router = express.Router();

/*
 * Bremse gegen Passwortraten: 10 Fehlversuche je IP und Kennung in 15 Minuten.
 * Im Speicher reicht - es gibt genau eine Backend-Instanz.
 */
const attempts = new Map();
const WINDOW = 15 * 60000;
function isLimited(key) {
  const now = Date.now();
  const recent = (attempts.get(key) || []).filter((t) => now - t < WINDOW);
  if (recent.length) attempts.set(key, recent);
  else attempts.delete(key);
  return recent.length >= 10;
}
function recordFailure(key) {
  attempts.set(key, [...(attempts.get(key) || []), Date.now()]);
}

// Oeffentlich: was zeigt der Anmeldeschirm?
router.get('/config', async (req, res, next) => {
  try {
    const { sso } = await getSettings();
    const ssoOn = Boolean(sso.enabled && ssoConfigured(sso));
    res.json({ sso_enabled: ssoOn, sso_label: sso.button_label, local_login: ssoOn ? sso.local_login !== false : true });
  } catch (err) {
    next(err);
  }
});

router.post('/login', async (req, res, next) => {
  const identifier = String(req.body?.identifier || '').trim();
  const password = String(req.body?.password || '');
  if (!identifier || !password) {
    return res.status(400).json({ error: 'Benutzername und Passwort sind erforderlich.' });
  }
  const key = `${req.ip}|${identifier.toLowerCase()}`;
  if (isLimited(key)) {
    return res.status(429).json({ error: 'Zu viele Fehlversuche. Bitte in 15 Minuten erneut versuchen.' });
  }

  try {
    const [rows] = await pool.query('SELECT * FROM pulse_users WHERE username = ? OR email = ? LIMIT 1', [
      identifier,
      identifier.toLowerCase(),
    ]);
    const user = rows[0];
    // Identische Meldung fuer "gibt es nicht" und "falsches Passwort".
    const ok = user?.password_hash ? await bcrypt.compare(password, user.password_hash) : false;
    if (!ok) {
      recordFailure(key);
      return res.status(401).json({ error: 'Benutzername oder Passwort ist falsch.' });
    }
    if (!user.is_active) return res.status(403).json({ error: 'Dieses Benutzerkonto ist deaktiviert.' });

    await pool.query('UPDATE pulse_users SET last_login_at = NOW() WHERE id = ?', [user.id]);
    res.json({ token: signToken(user), user: publicUser(user) });
  } catch (err) {
    next(err);
  }
});

router.get('/me', requireAuth, (req, res) => res.json({ user: publicUser(req.user) }));

// Eigene Darstellung: Design, Modus, Farbe, Profilbild.
router.patch('/me', requireAuth, async (req, res, next) => {
  const updates = {};
  if (req.body?.theme !== undefined) {
    const theme = req.body.theme;
    if (theme !== null && !['perinco', 'pixel', 'outdoor', 'cyberpunk', 'rainy', 'snow', 'aura'].includes(theme)) {
      return res.status(400).json({ error: 'Unbekanntes Design.' });
    }
    updates.theme = theme === 'perinco' ? null : theme;
  }
  if (req.body?.theme_mode !== undefined) {
    const mode = req.body.theme_mode;
    if (mode !== null && mode !== 'light' && mode !== 'dark') return res.status(400).json({ error: 'Unbekannter Modus.' });
    updates.theme_mode = mode;
  }
  if (req.body?.color !== undefined) {
    const color = req.body.color;
    if (color !== null && !/^#[0-9a-f]{6}$/i.test(color)) return res.status(400).json({ error: 'Ungültige Farbe.' });
    updates.color = color;
  }
  if (req.body?.avatar !== undefined) {
    const avatar = normalizeAvatar(req.body.avatar);
    if (avatar.error) return res.status(400).json({ error: avatar.error });
    updates.avatar = avatar.value;
  }
  const keys = Object.keys(updates);
  if (keys.length === 0) return res.status(400).json({ error: 'Keine Änderungen übergeben.' });
  try {
    await pool.query(`UPDATE pulse_users SET ${keys.map((k) => `${k} = ?`).join(', ')} WHERE id = ?`, [
      ...keys.map((k) => updates[k]),
      req.user.id,
    ]);
    res.json({ user: publicUser({ ...req.user, ...updates }) });
  } catch (err) {
    next(err);
  }
});

router.post('/change-password', requireAuth, async (req, res, next) => {
  const current = String(req.body?.current_password || '');
  const wanted = String(req.body?.new_password || '');
  if (wanted.length < 8) return res.status(400).json({ error: 'Das neue Passwort muss mindestens 8 Zeichen haben.' });
  try {
    const [rows] = await pool.query('SELECT password_hash FROM pulse_users WHERE id = ?', [req.user.id]);
    const hash = rows[0]?.password_hash;
    if (!hash) return res.status(400).json({ error: 'Dieses Konto meldet sich über SSO an und hat kein Passwort.' });
    if (!(await bcrypt.compare(current, hash))) return res.status(400).json({ error: 'Das aktuelle Passwort ist falsch.' });
    await pool.query('UPDATE pulse_users SET password_hash = ? WHERE id = ?', [await bcrypt.hash(wanted, 12), req.user.id]);
    res.json({ ok: true });
  } catch (err) {
    next(err);
  }
});

/* ---------------------------------------------------------------- SSO -- */

router.get('/sso/start', async (req, res, next) => {
  try {
    const { sso } = await getSettings();
    if (!sso.enabled || !ssoConfigured(sso)) {
      return res.redirect('/?sso_error=' + encodeURIComponent('SSO ist nicht eingerichtet.'));
    }
    const state = signShort({ n: crypto.randomBytes(12).toString('hex'), t: 'sso' });
    res.redirect(authorizeUrl(sso, state));
  } catch (err) {
    next(err);
  }
});

router.get('/sso/callback', async (req, res) => {
  const back = (message) => res.redirect('/?sso_error=' + encodeURIComponent(message));
  try {
    if (req.query.error) return back(String(req.query.error_description || req.query.error).split('\n')[0]);
    try {
      const state = verifyShort(String(req.query.state || ''));
      if (state.t !== 'sso') throw new Error('state');
    } catch {
      return back('Anmeldung abgelaufen. Bitte erneut versuchen.');
    }

    const { sso } = await getSettings();
    if (!sso.enabled || !ssoConfigured(sso)) return back('SSO ist nicht eingerichtet.');
    const identity = await exchangeCode(sso, String(req.query.code || ''));

    // Nur wer in der SSO-Verwaltung uebernommen wurde, kommt herein - verknuepft
    // wird ueber die Objekt-ID, nicht ueber die Mailadresse.
    const [rows] = await pool.query("SELECT * FROM pulse_users WHERE external_id = ? AND source = 'sso' LIMIT 1", [identity.oid]);
    const user = rows[0];
    if (!user) {
      return back(`Für ${identity.email || 'dieses Konto'} ist Pulse noch nicht freigeschaltet. Bitte an einen Manager oder Administrator wenden.`);
    }
    if (!user.is_active) return back('Dieses Benutzerkonto ist deaktiviert.');

    await pool.query('UPDATE pulse_users SET last_login_at = NOW() WHERE id = ?', [user.id]);
    // Token im Fragment: landet weder im Server-Log noch im Referer.
    res.redirect(`/#sso_token=${encodeURIComponent(signToken(user))}`);
  } catch (err) {
    console.error('[Pulse] SSO-Anmeldung fehlgeschlagen:', err.message);
    back('Anmeldung über Microsoft fehlgeschlagen: ' + err.message);
  }
});

export default router;