middleware.ts

import { getMiddlewareResponse } from "@plasmicapp/loader-nextjs/edge";
import { NextRequest,NextResponse } from "next/server";

export default async function middleware(req: NextRequest) {
    // Only pick a variation for GET requests
    if (req.method !== 'GET') {
      return;
    }

    const newUrl = req.nextUrl.clone();

    const PLASMIC_SEED = req.cookies.get('plasmic_seed');
  
    // Rewrite to a new pathname that encodes the custom traits for
    // this request, as well as some randomness for A/B tests
    const { pathname, cookies } = getMiddlewareResponse({
      path: newUrl.pathname,
      traits: {
        age: req.cookies.get('age')?.value || '',
      },
      cookies: {
        ...(PLASMIC_SEED ? { plasmic_seed: PLASMIC_SEED.value } : {})
      }
    });
  
    // Rewrite the response to use this new pathname
    newUrl.pathname = pathname;
    const res = NextResponse.rewrite(newUrl);
  
    // Save anything that needs to be saved in a cookie -- specifically,
    // the custom trait that corresponds to the random seed. The same
    // random seed will be used to pick the A/B test bucket each time
    // the user visits, to ensure that a visitor will always see the
    // same A/B test bucket.
    cookies.forEach((cookie) => {
      res.cookies.set(cookie.key, cookie.value);
    });
  
    return res;
}

// Exclude paths that are definitely not Plasmic pages with variations
export const config = {
  matcher: ['/:path((?!_next/|api/|favicon\\.ico|plasmic-host).*)']
};