using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.Serialization.Formatters;

using System.IO;

using System.Data;

using System.ComponentModel.DataAnnotations;

using System.Globalization;

using System.Reflection;

using System.Collections.ObjectModel;

​

using System.Runtime.Serialization;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

​

using Debug = System.Console;

​

//https://stackoverflow.com/questions/64474856/c-sharp-using-newtonsoft-json-defaultcontractresolver-ivalueprovider-to-replace

​

    public class JsonTester

    {

        public void Test()

        {

            var d = new Outer();

​

            var json = JsonConvert.SerializeObject(d,

                                                   Formatting.Indented,

                                                   new JsonSerializerSettings()

                                                   {

                                                       ContractResolver = new JsonContractResolver()

                                                   });

            Console.WriteLine(json);

        }

    }

​

    public interface IVariant

    {

        object Data { get; }

​

        string TypeName { get; set; }

    }

​

    public interface IVariantData

    {

    }

​

    [DataContract]

    public class Variant<TEnum, TData> : IVariant where TEnum : struct where TData : class, IVariantData, new()

    {

        [DataMember]

        public TData Data { get; }

​

        public string TypeName { get; set; }

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        object IVariant.Data => Data;

​

        public Variant()

        {

            Data = new TData();

        }

    }

​

    [DataContract]

    public sealed class VariantHolder

    {

        [DataContract]

        public class Joystick

        {

            [DataMember]

            public string Test { get; set; } = "Test";

        }

​

        [DataContract]

        public class Button

        {

            [DataMember]

            public string Test2 { get; set; } = "Test2";

        }

​

        [DataContract]

        public sealed class AimΞVariant : Variant<AimΞVariant.VariantEnum, AimΞVariant.VariantData>

        {

            public AimΞVariant()

            {

                TypeName = "Button";

            }

            public enum VariantEnum : byte

            {

                Joystick,

                Button

            }

​

            [DataContract]

            public sealed class VariantData : IVariantData

            {

                [DataMember]

                Joystick _Joystick = new Joystick();

​

                [DataMember]

                Button _Button = new Button();

​

                public Button Button => _Button;

                public Joystick Joystick => _Joystick;

            }

        }

​

        [DataMember]

        AimΞVariant Aim = new AimΞVariant();

    }

​

    [DataContract]

    public sealed class Outer

    {

        [DataMember]

        VariantHolder Data = new VariantHolder();

    }

​

    public class JsonContractResolver : DefaultContractResolver

    {

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

        {

            var property = base.CreateProperty(member, memberSerialization);

            if (typeof(IVariant).IsAssignableFrom(property.PropertyType))

            {

                property.ValueProvider = new IVariantValueProvider(member, property.PropertyType);

                property.DefaultValueHandling = DefaultValueHandling.Include;

                // The following fixes the InvalidCastException.  PropertyType has to be assignable from the type actually returned.

                // Since we don't know that at compile time, we need to set it to typeof(object).

                property.PropertyType = typeof(object);

                Debug.WriteLine("Used IVariantValueProvider for {0}", property);

            }

            return property;

        }

​

        protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)

        {

            var list = type.GetProperties().Where(x => x.GetCustomAttributes().Any(a => a.GetType() == typeof(DataMemberAttribute))).Select(p =>

            {

                return CreateProperty(p, memberSerialization);

            }).Concat(

            type.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public).Where(x => x.GetCustomAttributes().Any(a => a.GetType() == typeof(DataMemberAttribute))).Select(p =>

            {

                return CreateProperty(p, memberSerialization);

            })).ToList();

​

            return list;

        }

    }

​

    internal class IVariantValueProvider : IValueProvider

    {

        private MemberInfo member;

        private Type type;

​

        public IVariantValueProvider(MemberInfo member, Type type)

        {

            this.member = member;

            this.type = type;

        }

​

        public object GetValue(object target)

        {

            Debug.WriteLine("GetValue() called for {0}.{1}", target, member.Name);

            IVariant variant;

​

            switch (member)

            {

            case PropertyInfo p:

                variant = (IVariant)p.GetValue(target);

                break;

            case FieldInfo f:

                variant = (IVariant)f.GetValue(target);

                break;

            default:

                throw new InvalidCastException();

            }

​

            var dataType = variant.TypeName;

​

            var property = variant.Data.GetType().GetProperty(dataType);

​

            var value = property.GetValue(variant.Data);

​

            Debug.WriteLine("    Returned {0}", value);

            return value;

        }

​

        public void SetValue(object target, object value)

        {

            throw new NotImplementedException();

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            new JsonTester().Test();

        }   

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());

            Console.WriteLine("{0} version: {1}", typeof(JsonSerializer).Assembly.GetName().Name,  typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​