import { createI18nMiddleware } from 'fumadocs-core/i18n';
import { i18n } from '@/lib/i18n';
import { type NextRequest, NextResponse } from 'next/server';

// Old path redirects mapping
const exactMap: Record<string, string> = {
  '/docs': '/docs/introduction',
  '/docs/intro': '/docs/introduction',
  '/docs/guide/dashboard/workflow/coreferenceresolution':
    '/docs/introduction/guide/dashboard/workflow/coreferenceResolution',
  '/docs/guide/admin/sso_dingtalk':
    '/docs/introduction/guide/admin/sso#/docs/introduction/guide/admin/sso#钉钉',
  '/docs/guide/knowledge_base/rag': '/docs/introduction/guide/knowledge_base/RAG',
  '/docs/commercial/intro': '/docs/introduction/commercial',
  '/docs/upgrading/intro': '/docs/self-host/upgrading/upgrade-intruction',
  '/docs/upgrading': '/docs/self-host/upgrading/upgrade-intruction',
  '/docs/introduction/shopping_cart/intro/': '/docs/introduction/commercial',
  '/docs/introduction/cloud': '/docs/introduction/cloud/intro',
  '/docs/protocol/terms': '/docs/introduction/cloud/terms',
  '/docs/protocol/privacy': '/docs/introduction/cloud/privacy',
  '/docs/introduction/development/docker': '/docs/self-host/deploy/docker',
  '/docs/introduction/development/sealos': '/docs/self-host/deploy/sealos',
  '/docs/introduction/development/intro': '/docs/self-host/dev',
  '/docs/introduction/development/object-storage': '/docs/self-host/config/object-storage'
};

const prefixMap: Record<string, string> = {
  '/docs/FAQ': '/docs/faq',
  '/docs/guide': '/docs/introduction/guide',
  '/docs/shopping_cart': '/docs/introduction/shopping_cart',
  '/docs/upgrading': '/docs/self-host/upgrading',
  '/docs/development': '/docs/self-host',
  '/docs/introduction/development/openapi': '/docs/openapi',
  '/docs/introduction/development': '/docs/self-host'
};

const i18nMiddleware = createI18nMiddleware(i18n);

export default function middleware(request: NextRequest) {
  const { pathname } = request.nextUrl;

  // Extract language from pathname
  let lang = i18n.defaultLanguage;
  let pathWithoutLang = pathname;

  for (const language of i18n.languages) {
    if (pathname.startsWith(`/${language}`)) {
      lang = language;
      pathWithoutLang = pathname.slice(`/${language}`.length);
      break;
    }
  }

  // Check exact match redirects
  if (exactMap[pathWithoutLang]) {
    const newUrl = new URL(`/${lang}${exactMap[pathWithoutLang]}`, request.url);
    return NextResponse.redirect(newUrl, 301);
  }

  // Check prefix match redirects
  for (const [oldPrefix, newPrefix] of Object.entries(prefixMap)) {
    if (pathWithoutLang.startsWith(oldPrefix)) {
      const rest = pathWithoutLang.slice(oldPrefix.length);
      const newUrl = new URL(`/${lang}${newPrefix}${rest}`, request.url);
      return NextResponse.redirect(newUrl, 301);
    }
  }

  // Check if URL has a language prefix
  const hasLangPrefix = i18n.languages.some(
    (l) => pathname.startsWith(`/${l}/`) || pathname === `/${l}`
  );

  if (hasLangPrefix) {
    // Save user's language preference to cookie when visiting a localized URL
    const currentCookie = request.cookies.get('FD_LOCALE')?.value;
    if (currentCookie !== lang) {
      // @ts-expect-error - Fumadocs middleware signature mismatch
      const response = i18nMiddleware(request) ?? NextResponse.next();
      // @ts-ignore
      response.cookies.set('FD_LOCALE', lang, {
        path: '/',
        maxAge: 60 * 60 * 24 * 365
      });
      return response;
    }
  } else {
    // No language prefix — check cookie for user's language preference
    const cookieLocale = request.cookies.get('FD_LOCALE')?.value;
    if (cookieLocale && i18n.languages.includes(cookieLocale)) {
      const newUrl = new URL(`/${cookieLocale}${pathname}`, request.url);
      newUrl.search = request.nextUrl.search;
      return NextResponse.redirect(newUrl);
    }
  }

  // Continue with i18n middleware (falls back to Accept-Language detection)
  // @ts-expect-error - Fumadocs middleware signature mismatch
  return i18nMiddleware(request);
}

export const config = {
  matcher: [
    '/((?!api|_next/static|_next/image|favicon.ico|robots\\.txt|sitemap.*\\.xml|.*\\.svg|.*\\.png|deploy/.*).*)']
};