frontend/src/middleware.ts

/** Route protection middleware: redirects unauthenticated users away from /dashboard/*. */

import { type NextRequest, NextResponse } from "next/server";
import { createServerClient } from "@supabase/ssr";

// Routes that require authentication (prefix match)
const PROTECTED_PREFIXES = ["/dashboard"];

// Routes that authenticated users should NOT see (redirect to dashboard)
const AUTH_ROUTES = ["/login", "/signup"];

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

  // Create a Supabase server client that reads cookies from the request
  let supabaseResponse = NextResponse.next({ request });
  const supabase = createServerClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
    {
      cookies: {
        getAll() {
          return request.cookies.getAll();
        },
        setAll(cookiesToSet) {
          cookiesToSet.forEach(({ name, value, options }) =>
            request.cookies.set(name, value)
          );
          supabaseResponse = NextResponse.next({ request });
          cookiesToSet.forEach(({ name, value, options }) =>
            supabaseResponse.cookies.set(name, value, options)
          );
        },
      },
    }
  );

  // Refresh the session (important for token rotation)
  const {
    data: { user },
  } = await supabase.auth.getUser();

  const isProtectedRoute = PROTECTED_PREFIXES.some((prefix) =>
    pathname.startsWith(prefix)
  );
  const isAuthRoute = AUTH_ROUTES.some((route) => pathname.startsWith(route));

  // Redirect unauthenticated users away from protected routes
  if (isProtectedRoute && !user) {
    const homeUrl = new URL("/", request.url);
    homeUrl.searchParams.set("redirectTo", pathname);
    return NextResponse.redirect(homeUrl);
  }

  // Redirect authenticated users away from auth pages
  if (isAuthRoute && user) {
    return NextResponse.redirect(new URL("/dashboard", request.url));
  }

  return supabaseResponse;
}

export const config = {
  matcher: [
    /*
     * Match all routes except:
     * - _next/static (static files)
     * - _next/image (image optimization)
     * - favicon.ico
     * - public folder assets
     */
    "/((?!_next/static|_next/image|favicon.ico|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)",
  ],
};