[HttpPost]
        public void SetTheme(string data)
        {
            HttpCookie cookie = new HttpCookie("theme");
            cookie.Value = data;
            cookie.Expires = DateTime.Now.AddDays(1);
            Response.Cookies.Add(cookie);
        }

        [HttpPost]
        public void ChangeLanguage(string data)
        {
            HttpCookie cookie = new HttpCookie("language");
            cookie.Value = data;
            cookie.Expires = DateTime.Now.AddDays(1);
            Response.Cookies.Add(cookie);
        }

        [HttpPost]
        public async Task SetCurrency(string code)
        {
            HttpCookie cookie = new HttpCookie("currency");
            if (code == "pln")
            {
                cookie.Values.Add("name", "złotówka");
                cookie.Values.Add("code", "pln");
                cookie.Values.Add("value", "1");
            }
            else
            {
                CurrencyClient client = new CurrencyClient();
                CurrencyObject currency = await client.GetCurrencyAsync("a", code);
                cookie.Values.Add("name", currency.Currency);
                cookie.Values.Add("code", currency.Code);
                cookie.Values.Add("value", currency.Rates[0].Mid.ToString());
            }
            cookie.Expires = DateTime.Now.AddDays(1);
            Response.Cookies.Add(cookie);
        }