// Security middleware for GammaDesk
import type { Request, Response, NextFunction } from "express";

// Rate limiting store
interface RateLimitEntry {
  count: number;
  resetTime: number;
}

const rateLimitStore: Map<string, RateLimitEntry> = new Map();

// Whitelist for local development (home subnet)
const WHITELISTED_SUBNETS = [
  "192.168.",   // Home network
  "127.",       // Localhost
  "10.",        // Private network
  "fc00:",      // IPv6 local
  "::1",        // IPv6 localhost
];

function isWhitelisted(ip: string): boolean {
  return WHITELISTED_SUBNETS.some(prefix => ip.startsWith(prefix));
}

// Cleanup old rate limit entries every 60 seconds
const cleanupInterval = setInterval(() => {
  const now = Date.now();
  const expiredKeys: string[] = [];
  rateLimitStore.forEach((entry: RateLimitEntry, key: string) => {
    if (entry.resetTime < now) {
      expiredKeys.push(key);
    }
  });
  expiredKeys.forEach((key: string) => rateLimitStore.delete(key));
}, 60000);
if (cleanupInterval.unref) cleanupInterval.unref();

export function rateLimit({
  windowMs = 900000, // 15 minutes
  max = 500, // Relaxed from 100 for development
}: { windowMs?: number; max?: number } = {}) {
  return (req: Request, res: Response, next: NextFunction) => {
    const ip = req.ip || req.socket.remoteAddress || "unknown";

    // Skip rate limiting for whitelisted IPs (local development)
    if (isWhitelisted(ip)) {
      return next();
    }

    const now = Date.now();
    let entry = rateLimitStore.get(ip);

    if (!entry || now > entry.resetTime) {
      entry = { count: 1, resetTime: now + windowMs };
      rateLimitStore.set(ip, entry);
    } else {
      entry.count++;
    }

    res.set("X-RateLimit-Limit", String(max));
    res.set("X-RateLimit-Remaining", String(Math.max(0, max - entry.count)));
    res.set("X-RateLimit-Reset", String(Math.ceil(entry.resetTime / 1000)));

    if (entry.count > max) {
      return res.status(429).json({
        error: "Too many requests. Please try again later.",
        retryAfter: Math.ceil((entry.resetTime - now) / 1000),
      });
    }

    next();
  };
}

export function securityHeaders(_req: Request, res: Response, next: NextFunction) {
  res.set("X-Content-Type-Options", "nosniff");
  res.set("X-Frame-Options", "DENY");
  res.set("X-XSS-Protection", "1; mode=block");
  res.set("Referrer-Policy", "strict-origin-when-cross-origin");
  res.set("Permissions-Policy", "camera=(), microphone=(), geolocation=()");
  // Development CSP: Relaxed for Vite HMR + Google Fonts
  const devCsp = [
    "default-src 'self'",
    "script-src 'self' 'unsafe-inline' 'unsafe-eval' http: https: data:",
    "style-src 'self' 'unsafe-inline' https://fonts.googleapis.com",
    "img-src 'self' data: blob: https:",
    "font-src 'self' data: https://fonts.gstatic.com",
    "connect-src 'self' ws: wss: http: https:",
    "frame-ancestors 'none'",
    "base-uri 'self'",
    "form-action 'self'",
  ].join("; ");

  // Production CSP: Strict
  const prodCsp = [
    "default-src 'self'",
    "script-src 'self' 'unsafe-inline'",
    "style-src 'self' 'unsafe-inline' https://fonts.googleapis.com",
    "img-src 'self' data: blob:",
    "font-src 'self' data: https://fonts.gstatic.com",
    "connect-src 'self'",
    "frame-ancestors 'none'",
    "base-uri 'self'",
    "form-action 'self'",
  ].join("; ");

  res.set(
    "Content-Security-Policy",
    process.env.NODE_ENV === "production" ? prodCsp : devCsp,
  );

  if (process.env.NODE_ENV === "production") {
    res.set("Strict-Transport-Security", "max-age=31536000; includeSubDomains");
  }

  next();
}

export function sanitizeInput(input: string): string {
  return input
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#x27;");
}