// create a redirect URI using an available port on the loopback address.
        string redirectUri = string.Format("http://localhost:5000/signin-oidc/");

        // create an HttpListener to listen for requests on that redirect URI.
        var http = new HttpListener();
        http.Prefixes.Add(redirectUri);

        //Start listen
        http.Start();

        //set options for the OAuth2 Connection (Make these as parameters)
        var options = new OidcClientOptions
        {
            Authority = "https://identity.xero.com",
            ClientId = "",
            ClientSecret = "",
            Scope = "offline_access openid profile email accounting.settings accounting.transactions",
            RedirectUri = redirectUri
        };
        options.Policy.Discovery.ValidateEndpoints = false;

        var client = new OidcClient(options);
        var state = await client.PrepareLoginAsync();

        // open system browser to start authentication
        Process.Start(state.StartUrl);

        // wait for the authorization response.
        var context = await http.GetContextAsync();

        var result = await client.ProcessResponseAsync(context.Request.Url.AbsoluteUri, state);

        if (!result.IsError)
        {
            Console.WriteLine("\n\nClaims:");
            foreach (var claim in result.User.Claims)
            {
                Console.WriteLine("{0}: {1}", claim.Type, claim.Value);
            }

            Console.WriteLine();
            Console.WriteLine("Access token:\n{0}", result.AccessToken);

            if (!string.IsNullOrWhiteSpace(result.RefreshToken))
            {
                Console.WriteLine("Refresh token:\n{0}", result.RefreshToken);
            }
        }
        else
        {
            Console.WriteLine("\n\nError:\n{0}", result.Error);
        }           

        var responseString = string.Format("All Done close down your browser");
        byte[] buffer = Encoding.UTF8.GetBytes(responseString);

        // and send it
        var response = context.Response;
        response.ContentType = "text/html";
        response.ContentLength64 = buffer.Length;
        response.StatusCode = 200;
        response.OutputStream.Write(buffer, 0, buffer.Length);
        response.OutputStream.Close();

        http.Stop();		
		
		var AccountingApi = new AccountingApi();

        try
        {
            //Now connect to Accounting API and get invoices
			        //Parameters Access Token and TennantID
            var test = await AccountingApi.GetInvoicesAsync(result.AccessToken, "");
            MessageBox.Show("Number of Invoices: " + test._Invoices.Count.ToString()0;
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }

//If you save the result.AccessToken, result.RefreshToken for the use then when it expires, you can auto renew the Authentication

       // create a redirect URI using an available port on the loopback address.
        string redirectUri = string.Format("http://localhost:5000/signin-oidc/");
        Console.WriteLine("redirect URI: " + redirectUri);

        // create an HttpListener to listen for requests on that redirect URI.
        //var http = new HttpListener();
        //http.Prefixes.Add(redirectUri);
        //Console.WriteLine("Listening..");

        //Start listen
        //http.Start();

        //set options for the OAuth2 Connection (Make these as parameters)
        var options = new OidcClientOptions
        {
            Authority = "https://identity.xero.com",
            ClientId = "",
            ClientSecret = "",
            Scope = "offline_access openid profile email accounting.settings accounting.transactions",
            RedirectUri = redirectUri
        };
        options.Policy.Discovery.ValidateEndpoints = false;

        var client = new OidcClient(options);
        var state = await client.PrepareLoginAsync();

        Console.WriteLine($"Start URL: {state.StartUrl}");

        //refresh is the value saved from the initial authorisation from result.RefreshToken
        var result = await client.RefreshTokenAsync(refresh);

        if (!result.IsError)
        {
            //New Values after refresh
            tokencode = result.AccessToken;
            refresh = result.RefreshToken;
            expires = result.AccessTokenExpiration.ToString();
        }