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 Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;    

​

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

​

//https://stackoverflow.com/questions/57814077/how-can-i-choose-what-type-to-deserialize-at-runtime-based-on-the-structure-of-t/57814584#57814584

​

    public class StartingFunds

    {

        public double Value { get; set; }

    }

​

    [JsonConverter(typeof(DifficultyConverter))]

    public class Difficulty

    {

        public int CombatModifier { get; set; }

        public string Name { get; set; }

        public StartingFunds StartingFunds { get; set; }

        public List<string> Dwarves { get; set; }

    }

​

    public class RootObject

    {

        public List<Difficulty> Difficulty { get; set; }

    }

​

    public class Library

    {

        public static IEnumerable<Difficulty> EnumerateDifficulties()

        {

            return Enumerable.Range(1, 10).Select(i => new Difficulty { CombatModifier = i });

        }

    }

​

    public class DifficultyConverter : JsonConverter

    {

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

        {

            throw new NotImplementedException();

        }

​

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

        {

            var token = JToken.Load(reader);

            switch (token.Type)

            {

                case JTokenType.Null:

                    return null;

                case JTokenType.Integer:

                    {

                        var intv = (int)token;

                        return Library.EnumerateDifficulties().FirstOrDefault(d => d.CombatModifier == intv);

                    }

                case JTokenType.Object:

                    return token.DefaultToObject(objectType, serializer);

                default:

                    throw new JsonSerializationException(string.Format("Unknown token {0}", token.Type));

            }

        }                

​

        public override bool CanWrite => false;

​

        public override bool CanConvert(Type objectType) => objectType == typeof(Difficulty);

    }

    public static partial class JsonExtensions

    {

        public static object DefaultToObject(this JToken token, Type type, JsonSerializer serializer = null)

        {

            var oldParent = token.Parent;

            var dtoToken = new JObject(new JProperty(nameof(DefaultSerializationDTO<object>.Value), token));

            var dtoType = typeof(DefaultSerializationDTO<>).MakeGenericType(type);

            var dto = (IHasValue)(serializer ?? JsonSerializer.CreateDefault()).Deserialize(dtoToken.CreateReader(), dtoType);

            if (oldParent == null)

                token.RemoveFromLowestPossibleParent();

            return dto == null ? null : dto.GetValue();

        }

        public static JToken RemoveFromLowestPossibleParent(this JToken node)

        {

            if (node == null)

                return null;

            // If the parent is a JProperty, remove that instead of the token itself.

            var contained = node.Parent is JProperty ? node.Parent : node;

            contained.Remove();

            // Also detach the node from its immediate containing property -- Remove() does not do this even though it seems like it should

            if (contained is JProperty)

                ((JProperty)node.Parent).Value = null;

            return node;

        }

​

        interface IHasValue

        {

            object GetValue();

        }

​

        [JsonObject(NamingStrategyType = typeof(Newtonsoft.Json.Serialization.DefaultNamingStrategy), IsReference = false)]

        class DefaultSerializationDTO<T> : IHasValue

        {

            public DefaultSerializationDTO(T value) { this.Value = value; }

​

            public DefaultSerializationDTO() { }

            [JsonConverter(typeof(NoConverter)), JsonProperty(ReferenceLoopHandling = ReferenceLoopHandling.Serialize)]

            public T Value { get; set; }

            object IHasValue.GetValue() { return Value; }

        }

    }

​

    public class NoConverter : JsonConverter

    {

        // NoConverter taken from this answer https://stackoverflow.com/a/39739105/3744182

        // To https://stackoverflow.com/questions/39738714/selectively-use-default-json-converter

        // By https://stackoverflow.com/users/3744182/dbc

        public override bool CanConvert(Type objectType)  { throw new NotImplementedException(); /* This converter should only be applied via attributes */ }

​

        public override bool CanRead { get { return false; } }

​

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) { throw new NotImplementedException(); }

​

        public override bool CanWrite { get { return false; } }

​

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) { throw new NotImplementedException(); }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var json = GetJson();

            var settings = new JsonSerializerSettings

            {

                PreserveReferencesHandling = PreserveReferencesHandling.Objects,

            };

            var root = JsonConvert.DeserializeObject<RootObject>(json, settings);

            var json2 = JsonConvert.SerializeObject(root, Formatting.Indented, settings);

            Console.WriteLine(json2);

        }   

        static string GetJson()

        {

            var json = @"{

   ""Difficulty"":[

      {

         ""$id"":""625"",

         ""CombatModifier"":2,

         ""Name"":""Normal"",

         ""StartingFunds"":{

            ""$id"":""626"",

            ""Value"":2000.0

         },

         ""Dwarves"":[

            ""Miner"",

            ""Miner"",

            ""Miner"",

            ""Crafter""

         ]

      },

      2,

      {

         ""$ref"":""625""

      }

   ]

}

";

            return json;

        }

    }

​

​

    public class Program

    {

        public static void Main()

        {

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

            Console.WriteLine("Json.NET version: " + 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;

        }

    }

​