import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';
import createMiddleware from 'next-intl/middleware';
import { locales, defaultLocale } from '@/i18n/config';

/**
 * Combined Middleware for Multi-tenant ERP System
 *
 * Features:
 * 1. Internationalization (i18n) with locale detection
 * 2. Bot Detection and blocking for security
 * 3. Authentication and authorization (Sanctum/Bearer/API-Key)
 *
 * Strategy: Moderate bot blocking + Session-based auth
 * - Allows legitimate browsers and necessary crawlers
 * - Blocks bots from accessing sensitive ERP areas
 * - Protects routes with session/token authentication
 * - Prevents Chrome security warnings by not being too aggressive
 */

// Auth configuration
import { AUTH_CONFIG } from '@/lib/api/auth/auth-config';

// Create i18n middleware
const intlMiddleware = createMiddleware({
  locales,
  defaultLocale,
  localePrefix: 'as-needed', // Don't show default locale in URL
});

// Common bot user-agent patterns (case-insensitive)
const BOT_PATTERNS = [
  /bot/i,
  /crawler/i,
  /spider/i,
  /scraper/i,
  /curl/i,
  /wget/i,
  /python-requests/i,
  /scrapy/i,
  /axios/i,              // Programmatic access
  /headless/i,
  /phantom/i,
  /selenium/i,
  /puppeteer/i,
  /playwright/i,         // Browser automation tools
  /go-http-client/i,
  /java/i,
  /okhttp/i,
  /apache-httpclient/i,
];

// Paths that should be protected from bots
const PROTECTED_PATHS = [
  '/dashboard',
  '/admin',
  '/api',
  '/tenant',
  '/settings',
  '/users',
  '/reports',
  '/analytics',
  '/inventory',
  '/finance',
  '/hr',
  '/crm',
  '/employee',
  '/customer',
  '/supplier',
  '/orders',
  '/invoices',
  '/payroll',
];

// Paths that are allowed for everyone (including bots)
const PUBLIC_PATHS = [
  '/',
  '/login',
  '/about',
  '/contact',
  '/robots.txt',
  '/sitemap.xml',
  '/favicon.ico',
];

/**
 * Check if user-agent matches known bot patterns
 */
function isBot(userAgent: string): boolean {
  if (!userAgent) return false;

  return BOT_PATTERNS.some(pattern => pattern.test(userAgent));
}

/**
 * Check if user-agent is Internet Explorer
 * IE 11: Contains "Trident" in user-agent
 * IE 10 and below: Contains "MSIE" in user-agent
 */
function isInternetExplorer(userAgent: string): boolean {
  if (!userAgent) return false;

  return /MSIE|Trident/.test(userAgent);
}

/**
 * Check if the path should be protected from bots
 */
function isProtectedPath(pathname: string): boolean {
  return PROTECTED_PATHS.some(path => pathname.startsWith(path));
}

/**
 * Check if the path is public and accessible to all
 * Note: Currently unused but kept for future use
 */
function _isPublicPath(pathname: string): boolean {
  return PUBLIC_PATHS.some(path => pathname === path || pathname.startsWith(path));
}

/**
 * Remove locale prefix from pathname for bot checking
 */
function getPathnameWithoutLocale(pathname: string): string {
  for (const locale of locales) {
    if (pathname.startsWith(`/${locale}/`) || pathname === `/${locale}`) {
      return pathname.slice(`/${locale}`.length) || '/';
    }
  }
  return pathname;
}

/**
 * 인증 체크 함수
 * 3가지 인증 방식 지원: Bearer Token/Sanctum/API-Key
 */
function checkAuthentication(request: NextRequest): {
  isAuthenticated: boolean;
  authMode: 'sanctum' | 'bearer' | 'api-key' | null;
} {
  // 1. Bearer Token 확인 (쿠키에서)
  // access_token 또는 refresh_token이 있으면 인증된 것으로 간주
  const accessToken = request.cookies.get('access_token');
  const refreshToken = request.cookies.get('refresh_token');
  if ((accessToken && accessToken.value) || (refreshToken && refreshToken.value)) {
    return { isAuthenticated: true, authMode: 'bearer' };
  }

  // 2. Bearer Token 확인 (Authorization 헤더)
  const authHeader = request.headers.get('authorization');
  if (authHeader?.startsWith('Bearer ')) {
    return { isAuthenticated: true, authMode: 'bearer' };
  }

  // 3. Sanctum 세션 쿠키 확인 (레거시 지원)
  const sessionCookie = request.cookies.get('laravel_session');
  if (sessionCookie) {
    return { isAuthenticated: true, authMode: 'sanctum' };
  }

  // 4. API Key 확인
  const apiKey = request.headers.get('x-api-key');
  if (apiKey) {
    return { isAuthenticated: true, authMode: 'api-key' };
  }

  return { isAuthenticated: false, authMode: null };
}

/**
 * 라우트 타입 확인 함수들
 */
function isGuestOnlyRoute(pathname: string): boolean {
  return AUTH_CONFIG.guestOnlyRoutes.some(route =>
    pathname === route || pathname.startsWith(route)
  );
}

function isPublicRoute(pathname: string): boolean {
  return AUTH_CONFIG.publicRoutes.some(route => {
    // '/' 는 정확히 일치해야만 public
    if (route === '/') {
      return pathname === '/';
    }
    // 다른 라우트는 시작 일치 허용
    return pathname === route || pathname.startsWith(route + '/');
  });
}

export function middleware(request: NextRequest) {
  const { pathname } = request.nextUrl;
  const userAgent = request.headers.get('user-agent') || '';

  // 🚨 0️⃣ Internet Explorer Detection (최우선 처리)
  // IE 사용자는 지원 안내 페이지로 리다이렉트
  if (isInternetExplorer(userAgent)) {
    // unsupported-browser.html 페이지 자체는 제외 (무한 리다이렉트 방지)
    if (!pathname.includes('unsupported-browser')) {
      console.log(`[IE Blocked] ${userAgent} attempted to access ${pathname}`);
      return NextResponse.redirect(new URL('/unsupported-browser.html', request.url));
    }
  }

  // 1️⃣ 로케일 제거
  const pathnameWithoutLocale = getPathnameWithoutLocale(pathname);

  // 2️⃣ Bot Detection (기존 로직)
  const isBotRequest = isBot(userAgent);

  // Bot Detection: Block bots from protected paths
  if (isBotRequest && (isProtectedPath(pathname) || isProtectedPath(pathnameWithoutLocale))) {
    console.log(`[Bot Blocked] ${userAgent} attempted to access ${pathname}`);

    return new NextResponse(
      JSON.stringify({
        error: 'Access Denied',
        message: 'Automated access to this resource is not permitted.',
        code: 'BOT_ACCESS_DENIED'
      }),
      {
        status: 403,
        headers: {
          'Content-Type': 'application/json',
          'X-Robots-Tag': 'noindex, nofollow, noarchive, nosnippet',
        },
      }
    );
  }

  // 3️⃣ 정적 파일 제외
  if (
    pathname.includes('/_next/') ||
    pathname.includes('/api/') ||
    pathname.match(/\.(ico|png|jpg|jpeg|svg|gif|webp)$/)
  ) {
    return intlMiddleware(request);
  }

  // 4️⃣ 인증 체크
  const { isAuthenticated, authMode } = checkAuthentication(request);

  // 4.5️⃣ MVP: /signup 접근 차단 → /login 리다이렉트 (2025-12-04)
  // 회원가입 기능은 운영 페이지로 이동 예정
  if (pathnameWithoutLocale === '/signup' || pathnameWithoutLocale.startsWith('/signup/')) {
    console.log(`[Signup Blocked] Redirecting to /login from ${pathname}`);
    return NextResponse.redirect(new URL('/login', request.url));
  }

  // 5️⃣ 게스트 전용 라우트 (로그인/회원가입)
  if (isGuestOnlyRoute(pathnameWithoutLocale)) {
    // 이미 로그인한 경우 대시보드로
    if (isAuthenticated) {
      console.log(`[Already Authenticated] Redirecting to /dashboard from ${pathname}`);
      return NextResponse.redirect(new URL(AUTH_CONFIG.redirects.afterLogin, request.url));
    }
    // 비로그인 상태면 접근 허용
    return intlMiddleware(request);
  }

  // 6️⃣ 공개 라우트 (명시적으로 지정된 경우만)
  if (isPublicRoute(pathnameWithoutLocale)) {
    return intlMiddleware(request);
  }

  // 7️⃣ 기본 정책: 모든 페이지는 인증 필요
  // guestOnlyRoutes와 publicRoutes가 아닌 모든 경로는 보호됨
  if (!isAuthenticated) {
    console.log(`[Auth Required] Redirecting to /login from ${pathname}`);

    const url = new URL('/login', request.url);
    url.searchParams.set('redirect', pathname);
    return NextResponse.redirect(url);
  }

  // 8️⃣ 인증 모드 로깅 (디버깅용)
  if (isAuthenticated) {
    console.log(`[Authenticated] Mode: ${authMode}, Path: ${pathname}`);
  }

  // 9️⃣ i18n 미들웨어 실행
  const intlResponse = intlMiddleware(request);

  // 🔟 보안 헤더 추가
  intlResponse.headers.set('X-Robots-Tag', 'noindex, nofollow, noarchive, nosnippet');
  intlResponse.headers.set('X-Content-Type-Options', 'nosniff');
  intlResponse.headers.set('X-Frame-Options', 'DENY');
  intlResponse.headers.set('Referrer-Policy', 'strict-origin-when-cross-origin');

  // Bot 로깅 (모니터링용)
  if (isBotRequest) {
    console.log(`[Bot Allowed] ${userAgent} accessed ${pathname}`);
  }

  return intlResponse;
}

/**
 * Configure which paths the middleware should run on
 *
 * Matcher configuration:
 * - Excludes static files and assets
 * - Includes all app routes
 */
export const config = {
  matcher: [
    /*
     * Match all pathnames except:
     * - api routes
     * - _next/static (static files)
     * - _next/image (image optimization files)
     * - favicon.ico, robots.txt
     * - files with extensions (images, etc.)
     */
    '/((?!api|_next/static|_next/image|favicon.ico|.*\\..*|robots\\.txt).*)',
  ],
};