estimation-flow/middleware.ts

import { auth } from '@/app/api/auth/[...nextauth]/route';
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export async function middleware(request: NextRequest) {
  const session = await auth();
  const { pathname } = request.nextUrl;

  const isAuthPage = pathname === '/login';

  if (isAuthPage) {
    if (session) {
      return NextResponse.redirect(new URL('/admin', request.url));
    }
    return null;
  }

  if (!session && pathname.startsWith('/admin')) {
    const signInUrl = new URL('/login', request.url);
    signInUrl.searchParams.set('callbackUrl', pathname);
    return NextResponse.redirect(signInUrl);
  }

  return NextResponse.next();
}

export const config = {
  matcher: ['/admin/:path*', '/login'],
};