Wrapping services in IdentityServer

gistfile1.cs

    // definition
    public static class IdentityServerServiceFactoryExtensions
    {
        public static void Wrap<T>(this IdentityServerServiceFactory fact, 
            Func<T, T> wrapper, 
            Func<IdentityServerServiceFactory,Registration<T>> getter,
            Action<IdentityServerServiceFactory,Registration<T>> setter)
            where T: class
        {
            fact.Register(new HelperRegistration<T>(getter(fact), GetRegistrationNameFor(typeof(T))));
            setter(fact, new Registration<T>(resolver =>
            {
                var inner = resolver.Resolve<T>(GetRegistrationNameFor(typeof(T)));
                return wrapper(inner);
            }));
        }

        private static string GetRegistrationNameFor(Type t)
        {
            return t.FullName;
        }
    }

    internal class HelperRegistration<T> : Registration<T>
        where T: class
    {
        internal HelperRegistration(Registration<T> registration, string name)
        {
            if (registration == null) throw new ArgumentNullException("registration");
            if (name == null) throw new ArgumentNullException("name");

            this.Mode = registration.Mode;
            this.Type = registration.Type;
            this.Factory = registration.Factory;
            this.Instance = registration.Instance;
            this.Name = name;
        }
    }
    
    // usage
    factory.Wrap(
        inner => new UserServiceAdapter(inner),
        fact => fact.UserService,
        (fact, reg) => fact.UserService = reg);