'use strict';
const express = require('express');
const bcrypt = require('bcryptjs');
const speakeasy = require('speakeasy');
const qrcode = require('qrcode');
const multer = require('multer');
const path = require('path');
const fs = require('fs');
const crypto = require('crypto');
const { db } = require('../db');
const { log } = require('../lib/audit');
const { requireAuth } = require('../middleware/auth');

const router = express.Router();

const AVATAR_DIR = process.env.AVATAR_DIR || path.join(__dirname, '..', 'avatars');
fs.mkdirSync(AVATAR_DIR, { recursive: true });

const ALLOWED_AVATAR = { 'image/png': '.png', 'image/jpeg': '.jpg', 'image/webp': '.webp', 'image/gif': '.gif' };
const avatarUpload = multer({
  storage: multer.diskStorage({
    destination: (req, file, cb) => cb(null, AVATAR_DIR),
    filename: (req, file, cb) =>
      cb(null, `u${req.session.user.id}_${crypto.randomBytes(6).toString('hex')}${ALLOWED_AVATAR[file.mimetype] || ''}`),
  }),
  fileFilter: (req, file, cb) => cb(null, !!ALLOWED_AVATAR[file.mimetype]),
  limits: { fileSize: 4 * 1024 * 1024 },   // 4 MB
});

function publicUser(u) {
  return {
    id: u.id, username: u.username, email: u.email, role: u.role,
    mfa_enabled: !!u.mfa_enabled,
    avatar: u.avatar ? `/api/auth/avatar/${u.id}?v=${encodeURIComponent(u.avatar)}` : null,
  };
}

// Step 1: username + password. If MFA on, respond with mfa_required.
router.post('/login', (req, res) => {
  const { username, password, token } = req.body || {};
  const user = db.prepare('SELECT * FROM users WHERE username = ? OR email = ?').get(username, username);
  if (!user || !bcrypt.compareSync(password || '', user.password_hash)) {
    log(req, 'LOGIN_FAILED', 'Login', `Failed login for "${username}"`);
    return res.status(401).json({ error: 'Invalid username or password.' });
  }

  if (user.mfa_enabled) {
    if (!token) {
      return res.json({ mfa_required: true });
    }
    const ok = speakeasy.totp.verify({
      secret: user.mfa_secret,
      encoding: 'base32',
      token: String(token).replace(/\s/g, ''),
      window: 1,
    });
    if (!ok) {
      log(req, 'MFA_FAILED', 'Login', `Bad MFA code for "${user.username}"`);
      return res.status(401).json({ error: 'Invalid authentication code.' });
    }
  }

  req.session.user = publicUser(user);
  log(req, 'LOGIN', 'Login', `${user.username} signed in`);
  res.json({ ok: true, user: req.session.user });
});

router.post('/logout', requireAuth, (req, res) => {
  log(req, 'LOGOUT', 'Login', `${req.session.user.username} signed out`);
  req.session.destroy(() => res.json({ ok: true }));
});

router.get('/me', requireAuth, (req, res) => {
  const fresh = db.prepare('SELECT * FROM users WHERE id = ?').get(req.session.user.id);
  req.session.user = publicUser(fresh);
  res.json({ user: req.session.user });
});

// --- MFA ---------------------------------------------------------------
// Generate a secret + QR to scan. Secret is held on session until verified.
router.post('/mfa/setup', requireAuth, async (req, res) => {
  const secret = speakeasy.generateSecret({
    name: `Infosec (${req.session.user.username})`,
  });
  req.session.pending_mfa = secret.base32;
  const qr = await qrcode.toDataURL(secret.otpauth_url);
  res.json({ otpauth_url: secret.otpauth_url, qr, base32: secret.base32 });
});

// Verify the first code and turn MFA on.
router.post('/mfa/enable', requireAuth, (req, res) => {
  const { token } = req.body || {};
  const pending = req.session.pending_mfa;
  if (!pending) return res.status(400).json({ error: 'Start MFA setup first.' });
  const ok = speakeasy.totp.verify({
    secret: pending, encoding: 'base32',
    token: String(token || '').replace(/\s/g, ''), window: 1,
  });
  if (!ok) return res.status(400).json({ error: 'Code did not match. Try again.' });

  db.prepare('UPDATE users SET mfa_enabled = 1, mfa_secret = ? WHERE id = ?')
    .run(pending, req.session.user.id);
  delete req.session.pending_mfa;
  req.session.user.mfa_enabled = true;
  log(req, 'MFA_ENABLED', 'Account', `${req.session.user.username} enabled MFA`);
  res.json({ ok: true });
});

router.post('/mfa/disable', requireAuth, (req, res) => {
  const { password } = req.body || {};
  const user = db.prepare('SELECT * FROM users WHERE id = ?').get(req.session.user.id);
  if (!bcrypt.compareSync(password || '', user.password_hash)) {
    return res.status(401).json({ error: 'Password incorrect.' });
  }
  db.prepare('UPDATE users SET mfa_enabled = 0, mfa_secret = NULL WHERE id = ?')
    .run(user.id);
  req.session.user.mfa_enabled = false;
  log(req, 'MFA_DISABLED', 'Account', `${user.username} disabled MFA`);
  res.json({ ok: true });
});

// ---- Profile picture ---------------------------------------------------
// Upload (or replace) the signed-in user's picture.
function avatarUploadSafe(req, res, next) {
  avatarUpload.single('avatar')(req, res, (err) => {
    if (err) {
      const msg = err.code === 'LIMIT_FILE_SIZE'
        ? 'That image is larger than the 4 MB limit.'
        : 'Please choose a PNG, JPEG, WebP or GIF image (max 4 MB).';
      return res.status(400).json({ error: msg });
    }
    next();
  });
}

router.post('/avatar', requireAuth, avatarUploadSafe, (req, res) => {
  if (!req.file) {
    return res.status(400).json({ error: 'Please choose a PNG, JPEG, WebP or GIF image (max 4 MB).' });
  }
  const id = req.session.user.id;
  const prev = db.prepare('SELECT avatar FROM users WHERE id = ?').get(id);
  db.prepare('UPDATE users SET avatar = ?, avatar_mime = ? WHERE id = ?')
    .run(req.file.filename, req.file.mimetype, id);
  // Remove the old file so avatars do not accumulate on disk.
  if (prev && prev.avatar && prev.avatar !== req.file.filename) {
    try { fs.unlinkSync(path.join(AVATAR_DIR, prev.avatar)); } catch (_) { /* already gone */ }
  }
  req.session.user = publicUser(db.prepare('SELECT * FROM users WHERE id = ?').get(id));
  log(req, 'AVATAR_UPDATED', 'My Account', `${req.session.user.username} updated their profile picture`);
  res.json({ ok: true, avatar: req.session.user.avatar });
});

// Remove the signed-in user's picture.
router.delete('/avatar', requireAuth, (req, res) => {
  const id = req.session.user.id;
  const row = db.prepare('SELECT avatar FROM users WHERE id = ?').get(id);
  if (row && row.avatar) {
    try { fs.unlinkSync(path.join(AVATAR_DIR, row.avatar)); } catch (_) { /* already gone */ }
  }
  db.prepare('UPDATE users SET avatar = NULL, avatar_mime = NULL WHERE id = ?').run(id);
  req.session.user = publicUser(db.prepare('SELECT * FROM users WHERE id = ?').get(id));
  log(req, 'AVATAR_REMOVED', 'My Account', `${req.session.user.username} removed their profile picture`);
  res.json({ ok: true });
});

// Serve a user's picture. Any signed-in user may view another's (e.g. admins
// looking at the user list), but never without a session.
router.get('/avatar/:id', requireAuth, (req, res) => {
  const row = db.prepare('SELECT avatar, avatar_mime FROM users WHERE id = ?').get(Number(req.params.id));
  if (!row || !row.avatar) return res.status(404).send('No picture.');
  const file = path.join(AVATAR_DIR, row.avatar);
  if (!fs.existsSync(file)) return res.status(404).send('No picture.');
  if (row.avatar_mime) res.type(row.avatar_mime);
  res.setHeader('Cache-Control', 'private, max-age=300');
  res.sendFile(file);
});

module.exports = router;