I am trying to implement OIDC (Startup class) in our CMS solution.

How can I get the URLs to redirectUri (login action method), error and postlogoutRedirectUri (homepage) without hardcoding / getting from web.config ?

 public class Startup
    {
        private readonly string _clientId = "xxxxxx";
        private readonly string _redirectUri = "http://localhost:8080/OIDClogin";
        private readonly string _postLogoutRedirectUri = "http://localhost:8080/";
        private readonly string _authority = "xxxxx";
        private readonly string _clientSecret = "xxxxx";

        public void Configuration(IAppBuilder app)
        {
            // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=316888
            ConfigureAuth(app);
        }

        public void ConfigureAuth(IAppBuilder app)
        {
            //app.UseCookieAuthentication(new CookieAuthenticationOptions
            //{
            //    AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
            //    LoginPath = new PathString("/Home/Signin"),
            //    CookieSameSite = SameSiteMode.None,
            //});
            app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

            _ = app.UseOpenIdConnectAuthentication(new OpenIdConnectAuthenticationOptions
            {
                ClientId = _clientId,
                ClientSecret = _clientSecret,
                Authority = _authority,
                RedirectUri = _redirectUri,
                PostLogoutRedirectUri = _postLogoutRedirectUri,
                ResponseType = OpenIdConnectResponseType.CodeIdToken,