Send an event

// middleware.ts (in Next.js 16: proxy.ts, export function proxy)
import { NextResponse, type NextFetchEvent, type NextRequest } from "next/server";

const BOTS = /bot|crawl|spider|slurp|ChatGPT-User|Claude-User|Perplexity-User|meta-externalagent|anthropic-ai/i;

export function middleware(request: NextRequest, event: NextFetchEvent) {
  const userAgent = request.headers.get("user-agent") ?? "";
  const ip = request.headers.get("x-forwarded-for") ?? undefined;

  if (request.method === "GET" && BOTS.test(userAgent)) {
    event.waitUntil(
      fetch("https://useampersand.io/collect", {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${process.env.AMP_API_KEY}`,
          "Content-Type": "application/json"
        },
        body: JSON.stringify({
          event_name: "page_view",
          environment: "prod",
          context: {
            page: { url: request.url },
            client: { user_agent: userAgent, ip }
          }
        })
      }).catch(() => {})
    );
  }

  return NextResponse.next();
}

export const config = {
  matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"]
};

// Express, before your routes
// Behind a proxy or load balancer: app.set("trust proxy", true), so req.ip is the visitor
const BOTS = /bot|crawl|spider|slurp|ChatGPT-User|Claude-User|Perplexity-User|meta-externalagent|anthropic-ai/i;

app.use((req, res, next) => {
  const userAgent = req.get("user-agent") ?? "";

  if (req.method === "GET" && BOTS.test(userAgent)) {
    fetch("https://useampersand.io/collect", {
      method: "POST",
      headers: {
        "Authorization": `Bearer ${process.env.AMP_API_KEY}`,
        "Content-Type": "application/json"
      },
      body: JSON.stringify({
        event_name: "page_view",
        environment: "prod",
        context: {
          page: { url: `${req.protocol}://${req.get("host")}${req.originalUrl}` },
          client: { user_agent: userAgent, ip: req.ip }
        }
      })
    }).catch(() => {});
  }

  next();
});