workflow/docs/proxy.ts at d89c2f814730369fcff776bb378613086d944ec1 · vercel/workflow · GitHub

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import { createI18nMiddleware } from 'fumadocs-core/i18n/middleware';
import { isMarkdownPreferred, rewritePath } from 'fumadocs-core/negotiation';
import {
  type NextFetchEvent,
  type NextRequest,
  NextResponse,
} from 'next/server';
import { i18n } from '@/lib/geistdocs/i18n';
import { trackMdRequest } from '@/lib/md-tracking';
import { isAIAgent } from '@/lib/ai-agent-detection';

const { rewrite: rewriteLLM } = rewritePath(
  '/docs/*path',
  `/${i18n.defaultLanguage}/llms.mdx/*path`
);

const internationalizer = createI18nMiddleware(i18n);

const proxy = (request: NextRequest, context: NextFetchEvent) => {
  const pathname = request.nextUrl.pathname;

  // Track llms.txt requests
  if (pathname === '/llms.txt') {
    context.waitUntil(
      trackMdRequest({
        path: '/llms.txt',
        userAgent: request.headers.get('user-agent'),
        referer: request.headers.get('referer'),
        acceptHeader: request.headers.get('accept'),
      })
    );
  }

  // Handle .md/.mdx URL requests before i18n runs
  if (
    (pathname === '/docs.md' ||
      pathname === '/docs.mdx' ||
      pathname.startsWith('/docs/')) &&
    (pathname.endsWith('.md') || pathname.endsWith('.mdx'))
  ) {
    const stripped = pathname.replace(/\.mdx?$/, '');
    const result =
      stripped === '/docs'
        ? `/${i18n.defaultLanguage}/llms.mdx`
        : rewriteLLM(stripped);
    if (result) {
      context.waitUntil(
        trackMdRequest({
          path: pathname,
          userAgent: request.headers.get('user-agent'),
          referer: request.headers.get('referer'),
          acceptHeader: request.headers.get('accept'),
        })
      );
      return NextResponse.rewrite(new URL(result, request.nextUrl));
    }
  }

  // AI agent detection — rewrite docs pages to markdown for agents
  // so they always get structured content without needing .md URLs or Accept headers
  if (
    (pathname === '/docs' || pathname.startsWith('/docs/')) &&
    !pathname.includes('/llms.mdx/')
  ) {
    const agentResult = isAIAgent(request);
    if (agentResult.detected && !isMarkdownPreferred(request)) {
      const result =
        pathname === '/docs'
          ? `/${i18n.defaultLanguage}/llms.mdx`
          : rewriteLLM(pathname);

      if (result) {
        context.waitUntil(
          trackMdRequest({
            path: pathname,
            userAgent: request.headers.get('user-agent'),
            referer: request.headers.get('referer'),
            acceptHeader: request.headers.get('accept'),
            requestType: 'agent-rewrite',
            detectionMethod: agentResult.method,
          })
        );
        return NextResponse.rewrite(new URL(result, request.nextUrl));
      }
    }
  }

  // Handle Accept header content negotiation and track the request
  if (isMarkdownPreferred(request)) {
    const result = rewriteLLM(pathname);
    if (result) {
      context.waitUntil(
        trackMdRequest({
          path: pathname,
          userAgent: request.headers.get('user-agent'),
          referer: request.headers.get('referer'),
          acceptHeader: request.headers.get('accept'),
          requestType: 'header-negotiated',
        })
      );
      return NextResponse.rewrite(new URL(result, request.nextUrl));
    }
  }

  // Fallback to i18n middleware
  return internationalizer(request, context);
};

export const config = {
  // Matcher ignoring `/_next/`, `/api/`, static assets, favicon, sitemap, robots, etc.
  matcher: [
    '/((?!api|_next/static|_next/image|favicon.ico|sitemap.xml|robots.txt|og|.*\\.tgz$|.*\\.svg$|.*\\.zip$).*)',
  ],
};

export default proxy;