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 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/65889940/efficient-manual-deserialization-of-nested-objects-from-json-using-newtonsoft-in

​

    [Serializable]

    public class Mesh

    {

        public int[] Faces { get; set; }

        public Vec3[] Vertices { get; set; }

    }

​

    [Serializable]

    public class Vec3

    {

        public double X { get; set; }

        public double Y { get; set; }

        public double Z { get; set; }

    }

​

    public static partial class MeshExtensions

    {

        const string Vertices = "Vertices";

        const string Faces = "Faces";

        const string X = "X";

        const string Y = "Y";

        const string Z = "Z";

​

        public static Mesh FromJson(JsonTextReader reader)

        {

            var nameTable = new DefaultJsonNameTable();

            nameTable.Add(Vertices);

            nameTable.Add(Faces);

            nameTable.Add(X);

            nameTable.Add(Y);

            nameTable.Add(Z);

            reader.PropertyNameTable = nameTable;  // For performance

            reader.DateParseHandling = DateParseHandling.None;  // Possibly for performance.

​

            bool verticesFound = false;

            List<Vec3> vertices = null;

            bool facesFound = false;

            List<int> faces = null;

​

            while (reader.ReadToContent())

            {

                if (reader.TokenType == JsonToken.PropertyName && reader.Value == (object)Vertices)

                {

                    if (verticesFound)

                        throw new JsonSerializationException("Multiple vertices");

                    reader.ReadToContentAndAssert(); // Advance past the property name

                    vertices = ReadVertices(reader); // Read the vertices array

                    verticesFound = true;

                }

                else if (reader.TokenType == JsonToken.PropertyName && reader.Value == (object)Faces)

                {

                    if (facesFound)

                        throw new JsonSerializationException("Multiple faces");

                    reader.ReadToContentAndAssert(); // Advance past the property name

                    faces = reader.ReadIntArray(); // Read the vertices array

                    facesFound = true;

                }

            }

​

            return new Mesh

            {

                Vertices = vertices == null ? null : vertices.ToArray(),

                Faces = faces == null ? null : faces.ToArray(),

            };

        }

​

        static List<Vec3> ReadVertices(JsonTextReader reader)

        {

            if (reader.MoveToContentAndAssert().TokenType == JsonToken.Null)

                return null;

            else if (reader.TokenType != JsonToken.StartArray)

                throw new JsonSerializationException(string.Format("Unexpected token type {0}", reader.TokenType));

            var vertices = new List<Vec3>();

            while (reader.ReadToContent())

            {

                switch (reader.TokenType)

                {

                    case JsonToken.EndArray:

                        return vertices;

​

                    case JsonToken.Null:

                        // Or throw an exception if you prefer.

                        //throw new JsonSerializationException(string.Format("Unexpected token type {0}", reader.TokenType));

                        vertices.Add(null);

                        break;

​

                    case JsonToken.StartObject:

                        var vertex = ReadVertex(reader);

                        vertices.Add(vertex);

                        break;

​

                    default:

                        // reader.Skip();

                        throw new JsonSerializationException(string.Format("Unexpected token type {0}", reader.TokenType));

                }

            }

            throw new JsonReaderException(); // Truncated file.

        }

​

        static Vec3 ReadVertex(JsonTextReader reader)

        {

            if (reader.MoveToContentAndAssert().TokenType == JsonToken.Null)

                return null;

            else if (reader.TokenType != JsonToken.StartObject)

                throw new JsonException();

            var vec = new Vec3();

            while (reader.ReadToContent())

            {

                switch (reader.TokenType)

                {

                    case JsonToken.EndObject:

                        return vec;

​

                    case JsonToken.PropertyName:

                        if (reader.Value == (object)X)

                            vec.X = reader.ReadAsDouble().Value;

                        else if (reader.Value == (object)Y)

                            vec.Y = reader.ReadAsDouble().Value;

                        else if (reader.Value == (object)Z)

                            vec.Z = reader.ReadAsDouble().Value;

                        else // Skip unknown property names and values.

                            reader.ReadToContentAndAssert().Skip();

                        break;

​

                    default:

                        throw new JsonSerializationException(string.Format("Unexpected token type {0}", reader.TokenType));

                }

            }

            throw new JsonReaderException(); // Truncated file.

        }

    }

​

    public static class JsonExtensions

    {

        public static List<int> ReadIntArray(this JsonReader reader)

        {

            if (reader.MoveToContentAndAssert().TokenType == JsonToken.Null)

                return null;

            else if (reader.TokenType != JsonToken.StartArray)

                throw new JsonReaderException(string.Format("Unexpected token type {0}", reader.TokenType));

​

            var list = new List<int>();

            // ReadAsInt32() reads the next token as an integer, skipping comments

            for (var value = reader.ReadAsInt32(); true; value = reader.ReadAsInt32())

            {

                if (value != null)

                    list.Add(value.Value);

                else 

                    // value can be null if we reached the end of the array, encountered a null value, or encountered the end of a truncated file.

                    // JsonReader will throw an exception on most types of malformed file, but not on a truncated file.

                    switch (reader.TokenType)

                    {

                        case JsonToken.EndArray:

                            return list;

                        case JsonToken.Null:

                        default:

                            throw new JsonReaderException(string.Format("Unexpected token type {0}", reader.TokenType));

                    }

            }

        }

​

        public static bool ReadToContent(this JsonReader reader)

        {

            if (reader == null)

                throw new ArgumentNullException();

            if (!reader.Read())

                return false;

            while (reader.TokenType == JsonToken.Comment) // Skip past comments.

                if (!reader.Read())

                    return false;

            return true;

        }

​

        public static JsonReader ReadToContentAndAssert(this JsonReader reader)

        {

            return reader.ReadAndAssert().MoveToContentAndAssert();

        }

​

        public static JsonReader MoveToContentAndAssert(this JsonReader reader)

        {

            if (reader == null)

                throw new ArgumentNullException();

            if (reader.TokenType == JsonToken.None)       // Skip past beginning of stream.

                reader.ReadAndAssert();

            while (reader.TokenType == JsonToken.Comment) // Skip past comments.

                reader.ReadAndAssert();

            return reader;

        }

​

        public static JsonReader ReadAndAssert(this JsonReader reader)

        {

            if (reader == null)

                throw new ArgumentNullException();

            if (!reader.Read())

                throw new JsonReaderException("Unexpected end of JSON stream.");

            return reader;

        }

    }

​

    class TestClass

    {

        public static void Test()

        {

            var inputMesh = new Mesh

            {

                Faces = new[] { 0, 1, 2, 3 },

                Vertices = new[] { new Vec3 { X = 1, Y = 2, Z = 3 }, new Vec3 { X = double.PositiveInfinity, Y = double.MaxValue, Z = double.Epsilon }, new Vec3 { X = 1.0/3.0, Y = 2.0/3.0, Z = Math.PI } },

            };

​

            var json = JsonConvert.SerializeObject(inputMesh, Formatting.Indented);

​

            Console.WriteLine(json);

​

            using (var textReader = new StringReader(json))

            using (var jsonReader = new JsonTextReader(textReader))

            {

                var newMesh = MeshExtensions.FromJson(jsonReader);

​

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

​

                Console.WriteLine(json2);

​

                Assert.IsTrue(JToken.DeepEquals(JToken.Parse(json), JToken.Parse(json2)));

            }

​

            using (var textReader = new StringReader(GetJsonWithCommentsAndAddedProperties()))

            using (var jsonReader = new JsonTextReader(textReader))

            {

                var newMesh = MeshExtensions.FromJson(jsonReader);

​

                var deserializedMesh = JsonConvert.DeserializeObject<Mesh>(GetJsonWithCommentsAndAddedProperties());

​

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

​

                Console.WriteLine(json2);

​

                JToken.DeepEquals(JToken.Parse(json2), JToken.Parse(JsonConvert.SerializeObject(deserializedMesh)));

            }

​

            SimpleReaderTests();

        }

​

        static void SimpleReaderTests()

        {

            var json = @"{""value"" : /* comment */ 2 }";

​

            var value1 = JsonConvert.DeserializeAnonymousType(json, new { value = default(double) });

​

            using (var reader = new JsonTextReader(new StringReader(json)))

            {

                while (reader.Read())

                {

                    if (reader.TokenType == JsonToken.PropertyName)

                    {

                        var name = reader.Value;

                        var value2 = reader.ReadAsDouble();

​

                        Assert.IsTrue(value2 == value1.value);

                    }

                }

            }

​

            using (var reader = new JsonTextReader(new StringReader("[1, 2")))

            {

                Assert.Throws(typeof(JsonReaderException), () => reader.ReadIntArray());

            }

​

            using (var reader = new JsonTextReader(new StringReader("/**/ [/**/ 1/**/, /**/2 /**/ ]")))

            {

                var list = reader.ReadIntArray();

                Assert.IsTrue(new[] { 1, 2 }.SequenceEqual(list)); 

            }

​

            using (var reader = new JsonTextReader(new StringReader("[1, {}]")))

            {

                Assert.Throws(typeof(JsonReaderException), () => reader.ReadIntArray());

            }

​

            using (var reader = new JsonTextReader(new StringReader("[1}")))

            {

                Assert.Throws(typeof(JsonReaderException), () => reader.ReadIntArray());

            }

​

            using (var reader = new JsonTextReader(new StringReader("[1, null]")))

            {

                Assert.Throws(typeof(JsonReaderException), () => reader.ReadIntArray());

            }

​

            using (var reader = new JsonTextReader(new StringReader("[1, 2.2]")))

            {

                Assert.Throws(typeof(JsonReaderException), () => reader.ReadIntArray());

            }

        }

​

        static string GetJsonWithCommentsAndAddedProperties()

        {

            return @"{ ""SomeOtherArray"":[[[{},{""X"":""XXX""}]]],

/* COmment*/  ""Faces"": [ // COmment

    0, /* COmment*/

    /* COmment*/ 1,

    2/* COmment*/,

    /* COmment*/3

  ]/* COmment*/,

  ""Vertices"": [ /* COmment*/

    {/* COmment*/

      ""SomeOtherProperty"":  {/**/ ""X"" :/**/""XXX""/**/}/**/,

      ""X"": /* COmment*/ 1.0,

 /* COmment*/     ""Y"": /* COmment*/ 2.0,

   /* COmment*/   ""Z"": /* COmment*/3.0

    },

    {

     /* COmment*/ ""X"": ""Infinity"",

      ""Y"": 1.7976931348623157E+308,

      ""Z"": 4.94065645841247E-324,

      ""SomeOtherProperty"":{""X"":""XXX""}

    },

    {

 /* COmment*/     ""X"": 0.33333333333333331,

     /* COmment*/ ""Y"": 0.66666666666666663,

      ""Z"": 3.1415926535897931 /* COmment*/

    }/* COmment*/

​

/* COmment*/  ]

}";

        }

    }

    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.Location.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;

        }

    }

​