const express = require('express');
const axios = require('axios');
const crypto = require('crypto');
const rateLimit = require('express-rate-limit');
const router = express.Router();

// Persistent JSON file-backed token store — survives restarts
const { storeToken, getToken, clearToken } = require('../utils/tokenStore');

// Read EMBY_URL at request time (not module load time) so the value
// can be overridden by environment variables set after the module loads.
const getEmbyUrl = () => process.env.EMBY_URL;

// Strict login limiter: 10 attempts per 15 min, then locked for the window.
// Set SKIP_RATE_LIMIT=1 in the test environment to prevent the limiter from
// interfering with integration tests (all requests come from 127.0.0.1).
const loginLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: process.env.SKIP_RATE_LIMIT ? Number.MAX_SAFE_INTEGER : 10,
  standardHeaders: true,
  legacyHeaders: false,
  skipSuccessfulRequests: true, // only count failures toward the limit
  message: { success: false, error: 'Too many login attempts, please try again later' }
});

// Authenticate user with Emby
router.post('/login', loginLimiter, async (req, res) => {
  try {
    const { username, password, rememberMe } = req.body;

    // Input validation — reject obviously invalid inputs before hitting Emby
    if (typeof username !== 'string' || username.trim().length === 0 || username.length > 128) {
      return res.status(400).json({ success: false, error: 'Invalid username' });
    }
    if (typeof password !== 'string' || password.length === 0 || password.length > 256) {
      return res.status(400).json({ success: false, error: 'Invalid password' });
    }
    
    console.log(`[Auth] Attempting login for user: ${username.trim()}`);
    
    // Authenticate with Emby using a stable DeviceId derived from the username.
    // Using a deterministic DeviceId causes Emby to reuse the existing session
    // for this device rather than creating a new one on each login.
    const stableDeviceId = 'sofarr-' + crypto.createHash('sha256').update(username.trim().toLowerCase()).digest('hex').slice(0, 16);
    const authResponse = await axios.post(`${getEmbyUrl()}/Users/authenticatebyname`, {
      Username: username.trim(),
      Pw: password
    }, {
      headers: {
        'X-Emby-Authorization': `MediaBrowser Client="sofarr", Device="sofarr", DeviceId="${stableDeviceId}", Version="1.0.0"`
      }
    });
    
    const authData = authResponse.data;
    
    // Get user info using the access token
    const userResponse = await axios.get(`${getEmbyUrl()}/Users/${authData.User.Id || authData.User.id}`, {
      headers: {
        'X-MediaBrowser-Token': authData.AccessToken
      }
    });
    
    const user = userResponse.data;
    const isAdmin = !!(user.Policy && user.Policy.IsAdministrator);
    console.log(`[Auth] Login successful for user: ${user.Name}, isAdmin: ${isAdmin}`);

    // Store token server-side; it is never sent to the client.
    storeToken(user.Id, authData.AccessToken);
    
    // Set authentication cookie (signed when COOKIE_SECRET is set).
    // rememberMe=true  → persistent cookie, expires in 30 days
    // rememberMe=false → session cookie, expires when browser closes
    // secure:true only when TRUST_PROXY is set — i.e. a TLS-terminating reverse
    // proxy is in front. Without it the app may be accessed over plain HTTP and
    // secure cookies would never be sent back by the browser.
    const cookiePayload = JSON.stringify({ id: user.Id, name: user.Name, isAdmin });
    const signed = !!process.env.COOKIE_SECRET;
    const secureCookie = !!process.env.TRUST_PROXY; // only send over HTTPS when behind a TLS proxy
    const cookieOptions = {
      httpOnly: true,
      secure: secureCookie,
      sameSite: 'strict',
      signed,
      path: '/'
    };
    if (rememberMe) {
      cookieOptions.maxAge = 30 * 24 * 60 * 60 * 1000; // 30 days
    }
    res.cookie('emby_user', cookiePayload, cookieOptions);

    // Issue a CSRF token tied to this session so state-changing endpoints
    // can validate the double-submit cookie pattern
    const csrfToken = crypto.randomBytes(32).toString('hex');
    res.cookie('csrf_token', csrfToken, {
      httpOnly: false, // intentionally readable by JS for the double-submit pattern
      secure: secureCookie,
      sameSite: 'strict',
      path: '/'
    });
    
    res.json({
      success: true,
      user: { id: user.Id, name: user.Name, isAdmin },
      csrfToken
    });
  } catch (error) {
    console.error(`[Auth] Login failed:`, error.message);
    res.status(401).json({ 
      success: false, 
      error: 'Invalid username or password' 
    });
  }
});

function parseSessionCookie(req) {
  const signed = !!process.env.COOKIE_SECRET;
  const raw = signed ? req.signedCookies.emby_user : req.cookies.emby_user;
  if (!raw || raw === false) return null; // false = tampered signed cookie
  try {
    const u = JSON.parse(raw);
    // Schema validation: require id (string), name (string), isAdmin (boolean)
    if (typeof u.id !== 'string' || !u.id) return null;
    if (typeof u.name !== 'string' || !u.name) return null;
    if (typeof u.isAdmin !== 'boolean') u.isAdmin = !!u.isAdmin;
    return u;
  } catch {
    return null;
  }
}

// Get current authenticated user
router.get('/me', (req, res) => {
  const user = parseSessionCookie(req);
  if (!user) return res.json({ authenticated: false });
  res.json({
    authenticated: true,
    user: { id: user.id, name: user.name, isAdmin: user.isAdmin }
  });
});

// CSRF token refresh — lets the SPA get a new token without re-logging-in
// (e.g. after a page reload where the JS variable was lost)
router.get('/csrf', (req, res) => {
  const csrfToken = crypto.randomBytes(32).toString('hex');
  res.cookie('csrf_token', csrfToken, {
    httpOnly: false,
    secure: !!process.env.TRUST_PROXY,
    sameSite: 'strict',
    path: '/'
  });
  res.json({ csrfToken });
});

// Logout
router.post('/logout', async (req, res) => {
  const user = parseSessionCookie(req);
  if (user) {
    const stored = getToken(user.id);
    if (stored) {
      try {
        await axios.post(`${getEmbyUrl()}/Sessions/Logout`, {}, {
          headers: { 'X-MediaBrowser-Token': stored.accessToken }
        });
        console.log(`[Auth] Revoked Emby token for user: ${user.name}`);
      } catch (err) {
        console.warn(`[Auth] Failed to revoke Emby token for ${user.name}:`, err.message);
      }
      clearToken(user.id);
    }
  }
  res.clearCookie('emby_user', {
    httpOnly: true,
    secure: !!process.env.TRUST_PROXY,
    sameSite: 'strict',
    signed: !!process.env.COOKIE_SECRET,
    path: '/'
  });
  res.clearCookie('csrf_token', {
    httpOnly: false,
    secure: !!process.env.TRUST_PROXY,
    sameSite: 'strict',
    path: '/'
  });
  res.json({ success: true });
});

module.exports = router;
