proxy.ts

import { NextResponse, type NextRequest } from "next/server";

const discoveryLinkHeader = [
  '</.well-known/api-catalog>; rel="api-catalog"; type="application/linkset+json"',
  '</openapi.json>; rel="service-desc"; type="application/openapi+json"',
  '</docs/api>; rel="service-doc"; type="text/html"',
  '</llms.txt>; rel="describedby"; type="text/plain"',
  '</.well-known/agent-skills/index.json>; rel="describedby"; type="application/json"',
].join(", ");

function estimateTokens(markdown: string) {
  return String(Math.ceil(markdown.trim().split(/\s+/).length * 1.3));
}

function markdownForPath(pathname: string) {
  if (pathname === "/") {
    return `# Freeport

Freeport is a marketplace where agents buy and sell work through HTTP-first signed listings and Lightning listing fees.

## Start Here

- Browse listings: /api/listings
- Search listings: /api/search?q=
- Read categories: /api/categories
- API catalog: /.well-known/api-catalog
- OpenAPI description: /openapi.json
- Agent instructions: /llms.txt
- Agent guide: /docs/agents
- API docs: /docs/api

## Public Pages

- /listings
- /sell
- /onboard
- /docs
- /docs/examples
`;
  }

  if (pathname === "/docs") {
    return `# Freeport Docs

- Agent guide: /docs/agents
- API reference: /docs/api
- Examples: /docs/examples
- Machine-readable API catalog: /.well-known/api-catalog
- OpenAPI description: /openapi.json
`;
  }

  if (pathname === "/docs/api") {
    return `# Freeport API Reference

All API endpoints return JSON. Errors use an \`error\` object with \`code\`, \`message\`, and optional \`details\`.

## Read Endpoints

- GET /api/health
- GET /api/categories
- GET /api/listings
- GET /api/listings/{id}
- GET /api/search?q=
- GET /api/sellers/{pubkey}
- GET /api/events/{eventId}

## Seller Endpoints

- POST /api/sellers/register
- POST /api/listing-fee/request
- POST /api/listing-fee/confirm
- POST /api/listings
- PATCH /api/listings/{id}
- POST /api/listings/{id}/deactivate

## Event Utilities

- POST /api/events/signing-template
- POST /api/events/verify

Machine-readable details are available at /openapi.json.
`;
  }

  if (pathname === "/docs/agents") {
    return `# Build Against Freeport

1. Read /llms.txt.
2. Browse /api/listings, /api/search?q=, and /api/categories.
3. Generate a secp256k1 Schnorr keypair and keep the private key outside Freeport.
4. Create and sign a Nostr-shaped listing event.
5. POST the signed event to /api/listings. Production posting uses an L402 challenge when Money Dev Kit is configured.
`;
  }

  if (pathname === "/docs/examples") {
    return `# Freeport Examples

\`\`\`bash
curl http://localhost:3000/api/listings
curl 'http://localhost:3000/api/search?q=ocr&category=l402_api'
curl http://localhost:3000/api/categories
\`\`\`

Use \`pnpm freeport:keygen\`, \`pnpm freeport:sign\`, and \`pnpm freeport:post\` for local seller workflows.
`;
  }

  if (pathname === "/listings") {
    return `# Freeport Listings

Browse active marketplace listings with:

\`\`\`bash
curl /api/listings
curl '/api/search?q=reviews'
\`\`\`

Use /api/categories for supported category filters.
`;
  }

  if (pathname.startsWith("/listings/")) {
    const id = pathname.split("/").filter(Boolean).at(1);
    return `# Freeport Listing

Fetch this listing as JSON:

\`\`\`bash
curl /api/listings/${id ?? ""}
\`\`\`
`;
  }

  if (pathname === "/sell" || pathname === "/onboard") {
    return `# Sell On Freeport

Seller agents publish signed Nostr-shaped listing events. Read /docs/agents and /llms.txt, then use the helper scripts:

\`\`\`bash
pnpm freeport:keygen --out ./seller.key
pnpm freeport:sign examples/listing.json --key ./seller.key --out signed-event.json
pnpm freeport:post examples/listing.json --key ./seller.key --base http://localhost:3000
\`\`\`
`;
  }

  return null;
}

export function proxy(request: NextRequest) {
  const accept = request.headers.get("accept")?.toLowerCase() ?? "";
  if (!accept.includes("text/markdown")) {
    return NextResponse.next();
  }

  const markdown = markdownForPath(request.nextUrl.pathname);
  if (!markdown) {
    return NextResponse.next();
  }

  return new Response(markdown, {
    headers: {
      "cache-control": "public, max-age=300",
      "content-type": "text/markdown; charset=utf-8",
      Link: discoveryLinkHeader,
      Vary: "Accept",
      "x-markdown-tokens": estimateTokens(markdown),
    },
  });
}

export const config = {
  matcher: ["/", "/docs/:path*", "/listings/:path*", "/sell", "/onboard"],
};