login script cas

final response = await HttpRequest.get(loginUrl);

    if (!response.isSuccess) return LoginResult(LoginResultType.NETWORK_ERROR);

    final document = parse(response.httpResponse.body);

    // Extract lt value from HTML
    final ltInput = document.querySelector('input[name="lt"]');
    String lt = "";
    if (ltInput?.attributes?.containsKey("value") ?? false)
      lt = ltInput.attributes['value'];

    final executionInput = document.querySelector('input[name="execution"]');
    String execution = "e1s1";
    if (executionInput?.attributes?.containsKey("value") ?? false)
      execution = executionInput.attributes['value'];

    // POST data
    Map<String, String> postParams = {
      "_eventId": "submit",
      "lt": lt,
      "submit": "LOGIN",
      "username": username,
      "password": password,
      "execution": execution,
    };

    // Get JSESSIONID from previous request header
    final cookie = response.httpResponse.headers["set-cookie"];

    // Second request, with all necessary data
    final loginResponse = await HttpRequest.post(
      loginUrl,
      body: postParams,
      headers: {"cookie": cookie},
    );