Simple Language module for Owin .NET C#

Language.cs

 public class LanguageComponent
    {

        App _next;
        //sv-SE
        string fallback = ConfigurationManager.AppSettings["language"];
        //sv-SE,en-EN etc
        string[] accepted = ConfigurationManager.AppSettings["accepted-languages"].Split(',');
        

        public LanguageComponent(App next)
        {
            _next = next;
        }

        public async Task Invoke(IDictionary<string, object> environment)
        {
            var cookies = environment["Microsoft.Owin.Cookies#dictionary"] as IDictionary<string, string>;
            var language = string.Empty;

            if (cookies.ContainsKey("_language"))
            {
                language = cookies["_language"];
            }
            else
            {
                var headers = environment["owin.RequestHeaders"] as IDictionary<string, string[]>;
                if (headers.ContainsKey("Accept-Language"))
                {
                    var languages = headers["Accept-Language"];
                    var first = languages[0];
                    language = first.Split(',')[0];
                }

                var cookie = new HttpCookie("_language");

                cookie.Value = accepted.Contains(language) ? language : fallback;
                
                
                HttpContext.Current.Response.Cookies.Add(cookie);
            }

            SetCulture(accepted.Contains(language) ? language : fallback);

            await _next(environment);
        }


        public void SetCulture(string culture)
        {
            Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo(culture);
            Thread.CurrentThread.CurrentUICulture = Thread.CurrentThread.CurrentCulture;
        }
    }