Including multi-tenant config into tRPC context

export const config = {
  matcher: [
    /*
     * Match all paths except for:
     * 1. /api routes
     * 2. /_next (Next.js internals)
     * 3. /_static (inside /public)
     * 4. all root files inside /public (e.g. /favicon.ico)
     * 5. All files inside subdirectories of /public/static
     */
    '/((?!api/|_next/|_static/|static/|_vercel|[\\w-]+\\.\\w+).*)',
  ],
};

export default function middleware(req: NextRequest) {
  const url = req.nextUrl;

  // Get hostname of request (e.g. demo.vercel.pub, demo.localhost:3000)
  const hostname = req.headers
    .get('host')!
    .replace('.localhost:3000', `.${ROOT_DOMAIN}`);

  const searchParams = req.nextUrl.searchParams.toString();
  const path = `${url.pathname}${
    searchParams.length > 0 ? `?${searchParams}` : ''
  }`;

  // Rewrite root to `/app`
  if (hostname === 'localhost:3000' || hostname === ROOT_DOMAIN) {
    return NextResponse.rewrite(
      new URL(`/app${path === '/' ? '' : path}`, req.url),
    );
  }

  const tenantSlug = hostname.replace(`.${ROOT_DOMAIN}`, '');

  // Rewrite everything else to `/[tenantSlug]`
  return NextResponse.rewrite(new URL(`/${tenantSlug}${path}`, req.url));
}

export async function createContext(
  ctx: CreateWSSContextFnOptions | CreateNextContextOptions,
): Promise<{
  session: Session | null;
  req: IncomingMessage | NextApiRequest;
  res: ws | NextApiResponse;
  prisma: ExtendedPrismaClient;
}> {
  const { req, res } = ctx;

  let session: Session | null;
  try {
    // @ts-expect-error -- This will fail if called client side
    session = await getServerSession(req, res, getAuthOptions(req));
  } catch (error) {
    session = await getSession(ctx);
  }

  const contextInner = await createContextInner();

  return {
    ...contextInner,
    session,
    req,
    res,
  };
}