public async Task RefreshToken()

in OAuthWebSample/OAuthWebSample/Controllers/OAuthController.cs [159:203]
37 lines of code
4 McCabe index (conditional complexity)

        public async Task<ActionResult> RefreshToken(string refreshToken)
        {
            String error = null;
            if (!String.IsNullOrEmpty(refreshToken))
            {
                // Form the request to exchange an auth code for an access token and refresh token
                HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Post, ConfigurationManager.AppSettings["TokenUrl"]);
                requestMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                Dictionary<String, String> form = new Dictionary<String, String>()
                {
                    { "client_assertion_type", "urn:ietf:params:oauth:client-assertion-type:jwt-bearer" },
                    { "client_assertion", ConfigurationManager.AppSettings["ClientAppSecret"] },
                    { "grant_type", "refresh_token" },
                    { "assertion", refreshToken },
                    { "redirect_uri", ConfigurationManager.AppSettings["CallbackUrl"] }
                };
                requestMessage.Content = new FormUrlEncodedContent(form);

                // Make the request to exchange the auth code for an access token (and refresh token)
                HttpResponseMessage responseMessage = await s_httpClient.SendAsync(requestMessage);

                if (responseMessage.IsSuccessStatusCode)
                {
                    // Handle successful request
                    String body = await responseMessage.Content.ReadAsStringAsync();
                    ViewBag.Token = JObject.Parse(body).ToObject<TokenModel>();
                }
                else
                {
                    error = responseMessage.ReasonPhrase;
                }
            }
            else
            {
                error = "Invalid refresh token";
            }

            if (!String.IsNullOrEmpty(error))
            {
                ViewBag.Error = error;
            }

            return View("TokenView");
        }