protected override async Task <AuthenticationTicket> AuthenticateCoreAsync()
        {
            AuthenticationProperties properties = null;

            try
            {
                string code  = null;
                string state = null;

                var query  = Request.Query;
                var values = query.GetValues("code");
                if (values != null && values.Count == 1)
                {
                    code = values[0];
                }
                values = query.GetValues("state");
                if (values != null && values.Count == 1)
                {
                    state = values[0];
                }

                properties = Options.StateDataFormat.Unprotect(state);
                if (properties == null)
                {
                    return(null);
                }

                // OAuth2 10.12 CSRF

                // Why does this fail!?
                if (!ValidateCorrelationId(properties, _logger))
                {
                    return(new AuthenticationTicket(null, properties));
                }

                var cookieOptions = new CookieOptions
                {
                    HttpOnly = true,
                    Secure   = Request.IsSecure
                };

                string correlationKey = ".AspNet.Correlation." + Options.AuthenticationType;
                Response.Cookies.Delete(correlationKey, cookieOptions);

                var requestPrefix = Request.Scheme + "://" + Request.Host;
                var redirectUri   = requestPrefix + Request.PathBase + Options.CallbackPath;

                //// Build up the body for the token request
                //var body = new List<KeyValuePair<string, string>>
                //{
                //    new KeyValuePair<string, string>("code", code),
                //    new KeyValuePair<string, string>("redirect_uri", redirectUri),
                //    new KeyValuePair<string, string>("client_id", Options.ClientId),
                //    new KeyValuePair<string, string>("client_secret", Options.ClientSecret)
                //};

                //// Request the token
                //var requestMessage = new HttpRequestMessage(HttpMethod.Post, Options.Endpoints.TokenEndpoint);
                //requestMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                //requestMessage.Content = new FormUrlEncodedContent(body);
                //var tokenResponse = await _httpClient.SendAsync(requestMessage);
                //tokenResponse.EnsureSuccessStatusCode();
                //var text = await tokenResponse.Content.ReadAsStringAsync();

                //// Deserializes the token response
                //dynamic response = JsonConvert.DeserializeObject<dynamic>(text);
                //var accessToken = (string)response.access_token;

                // Get the xx user
                //var userRequest = new HttpRequestMessage(HttpMethod.Get, Options.Endpoints.UserInfoEndpoint + "?access_token=" + Uri.EscapeDataString(accessToken));
                //userRequest.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                //var userResponse = await _httpClient.SendAsync(userRequest, Request.CallCancelled);
                //userResponse.EnsureSuccessStatusCode();
                //text = await userResponse.Content.ReadAsStringAsync();

                // shortcut extra oauth2 token request since lnauth is simpler with linking key
                //var accessToken = code;

                //var user = JObject.Parse("");

                var context = new LnAuthAuthenticatedContext(Context, linkingKey: code)
                {
                    Identity = new ClaimsIdentity(
                        Options.AuthenticationType,
                        ClaimsIdentity.DefaultNameClaimType,
                        ClaimsIdentity.DefaultRoleClaimType)
                };

                //if (!string.IsNullOrEmpty(context.Id))
                //{
                context.Identity.AddClaim(new Claim(ClaimTypes.NameIdentifier, code, XmlSchemaString, Options.AuthenticationType));
                //}

                if (!string.IsNullOrEmpty(context.LinkingKey))
                {
                    context.Identity.AddClaim(new Claim("urn:lnurl-auth:linkingkey", context.LinkingKey, XmlSchemaString, Options.AuthenticationType));
                }

                //if (!string.IsNullOrEmpty(context.UserName))
                //{
                context.Identity.AddClaim(new Claim(ClaimsIdentity.DefaultNameClaimType, "LNAUTH", XmlSchemaString, Options.AuthenticationType));
                //}
                //if (!string.IsNullOrEmpty(context.Email))
                //{
                context.Identity.AddClaim(new Claim(ClaimTypes.Email, "", XmlSchemaString, Options.AuthenticationType));
                //}
                //else if (Options.Scope.Any(x=> x == "user" || x == "user:email"))
                //{
                //    var userRequest2 = new HttpRequestMessage(HttpMethod.Get, Options.Endpoints.UserInfoEndpoint + "/emails" + "?access_token=" + Uri.EscapeDataString(accessToken));
                //    userRequest2.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                //    var userResponse2 = await _httpClient.SendAsync(userRequest2, Request.CallCancelled);
                //    userResponse2.EnsureSuccessStatusCode();
                //    text = await userResponse2.Content.ReadAsStringAsync();
                //    var emails = JsonConvert.DeserializeObject<List<UserEmail>>(text);
                //    if (emails.Any())
                //    {
                //        var primaryEmail = emails.FirstOrDefault(x => x.Primary && x.Verified);
                //        if (primaryEmail != null)
                //        {
                //            context.Identity.AddClaim(new Claim(ClaimTypes.Email, primaryEmail.Email, XmlSchemaString,
                //        Options.AuthenticationType));
                //        }
                //    }
                //}
                //if (!string.IsNullOrEmpty(context.Name))
                //{
                //    context.Identity.AddClaim(new Claim("urn:github:name", context.Name, XmlSchemaString, Options.AuthenticationType));
                //}
                //if (!string.IsNullOrEmpty(context.Link))
                //{
                //    context.Identity.AddClaim(new Claim("urn:github:url", context.Link, XmlSchemaString, Options.AuthenticationType));
                //}

                context.Properties = properties;

                await Options.Provider.Authenticated(context);

                return(new AuthenticationTicket(context.Identity, context.Properties));
            }
            catch (Exception ex)
            {
                _logger.WriteError(ex.Message);
            }
            return(new AuthenticationTicket(null, properties));
        }
 /// <summary>
 /// Invoked whenever Lnauth successfully authenticates a user
 /// </summary>
 /// <param name="context">Contains information about the login session as well as the user <see cref="System.Security.Claims.ClaimsIdentity"/>.</param>
 /// <returns>A <see cref="Task"/> representing the completed operation.</returns>
 public virtual Task Authenticated(LnAuthAuthenticatedContext context)
 {
     return(OnAuthenticated(context));
 }