import jwt from 'jsonwebtoken';
import { v4 as uuidv4 } from 'uuid';
import { getDb } from '../config/database.js';
import redis from '../config/redis.js';
import { log } from '../config/logger.js';

if (!process.env.JWT_SECRET) {
  log.auth.error('FATAL: JWT_SECRET environment variable is not set.');
  process.exit(1);
}
const JWT_SECRET = process.env.JWT_SECRET;

export async function authenticateToken(req, res, next) {
  const authHeader = req.headers.authorization;
  const token = authHeader && authHeader.split(' ')[1];

  if (!token) {
    return res.status(401).json({ error: 'Authentication required' });
  }

  try {
    const decoded = jwt.verify(token, JWT_SECRET);

    // Check JWT blacklist in DragonflyDB (revoked tokens via logout)
    if (decoded.jti) {
      try {
        const revoked = await redis.get(`blacklist:${decoded.jti}`);
        if (revoked) {
          return res.status(401).json({ error: 'Token has been revoked' });
        }
      } catch (redisErr) {
        // Graceful degradation: if Redis is unavailable, allow the request
        log.auth.warn(`Redis blacklist check skipped: ${redisErr.message}`);
      }
    }

    const db = getDb();
    const user = await db.get('SELECT id, name, display_name, email, role, theme, language, avatar_color, avatar_image, email_verified FROM users WHERE id = ?', [decoded.userId]);
    if (!user) {
      return res.status(401).json({ error: 'User not found' });
    }
    req.user = user;
    next();
  } catch (err) {
    return res.status(403).json({ error: 'Invalid token' });
  }
}

export function requireAdmin(req, res, next) {
  if (req.user.role !== 'admin') {
    return res.status(403).json({ error: 'Admin rights required' });
  }
  next();
}

export function generateToken(userId) {
  const jti = uuidv4();
  return jwt.sign({ userId, jti }, JWT_SECRET, { expiresIn: '7d' });
}

/**
 * Build the public base URL for the application.
 * Prefers APP_URL env var. Falls back to X-Forwarded-Proto + Host header
 * so that links are correct behind a TLS-terminating reverse proxy.
 */
export function getBaseUrl(req) {
  if (process.env.APP_URL) return process.env.APP_URL.replace(/\/+$/, '');
  const proto = req.get('x-forwarded-proto')?.split(',')[0]?.trim() || req.protocol;
  return `${proto}://${req.get('host')}`;
}