import { NextResponse } from "next/server";
import type { NextRequest } from "next/server";
import { parseHost } from "@/lib/host";

// Host → URL-rewrite. Acme visits acme.localhost:3000/dashboard; we
// internally rewrite to /acme/dashboard so the [slug] route group renders.
// URL bar stays unchanged.
//
// Backstage (backstage.<apex>) rewrites to /__backstage__/<rest>.
// Apex hosts (localhost, breakpilot.com) get a marketing/landing page
// at the root route.

export function middleware(request: NextRequest) {
  const match = parseHost(request.headers.get("host"));
  const url = request.nextUrl.clone();

  if (match.kind === "tenant") {
    if (!url.pathname.startsWith(`/${match.slug}/`) && url.pathname !== `/${match.slug}`) {
      url.pathname = `/${match.slug}${url.pathname === "/" ? "" : url.pathname}`;
      return NextResponse.rewrite(url);
    }
  } else if (match.kind === "backstage") {
    if (!url.pathname.startsWith("/__backstage__")) {
      url.pathname = `/__backstage__${url.pathname === "/" ? "" : url.pathname}`;
      return NextResponse.rewrite(url);
    }
  }

  return NextResponse.next();
}

export const config = {
  // Skip Next internals + API + static assets so middleware doesn't
  // double-rewrite the auth callback or _next/static.
  matcher: ["/((?!api|_next/static|_next/image|favicon.ico).*)"],
};