Server functions with state

export function createAuthServerFns(client: Client, auth: Promise<Auth>, options: TanStackAuthOptions) {
  const authMiddleware = createAuthMiddleware(client, auth, options);

  const withSession = createMiddleware({ type: "function" })
    .middleware([authMiddleware])
    .server(({ next, context }) => {
      const { __gel_auth: auth } = context;
      const authCookie = getCookie(auth.options.authCookieName) || getCookie(DEFAULT_AUTH_COOKIE);

      return next({ context: { ...context, session: { client: auth.client, authCookie } } });
    });

  const startOAuth = createServerFn()
    .middleware([authMiddleware])
    .inputValidator(({ providerName }: { providerName: BuiltinOAuthProviderNames }) => {
       ...
    })
    .handler(async ({ data: { providerName }, context: { __gel_auth: auth } }) => {
      const pkceSession = await auth.core.then((core: Auth) => core.createPKCESession());
      createVerifierCookie(auth, pkceSession.verifier);
      const url = getUrl(auth);
      return Response.redirect(pkceSession.getOAuthUrl(providerName, url, `${url}?isSignUp=true`));
    });

  const handleCallback = createFileRoute('/_auth/login/complete')({
    params: {parse: (data: Record<"error" | "code" | "error_description" | "provider" | "isSignUp", string | undefined>) => {
         ...
       }
    },
    server: {
       middleware: [authMiddleware],
       handler: {
         ANY: (async ({ data: { provider, code, isSignUp }, context: { __gel_auth: auth } }) => {
            ...
          }
       }
    )

  const handleSignout = createServerFn()
    .middleware([authMiddleware])
    .handler(async ({ context: { __gel_auth: auth } }) => {
      clearAuthCookie(auth);
      return { success: true };
    });

  return {
    authMiddleware,
    withSession,
    getProvidersInfo,
    startOAuth,
    handleCallback,
    handleSignout,
  };
}