using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

using System.Data;

using System.Reflection;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Serialization;

​

using Microsoft.Extensions.Configuration;

​

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

​

#nullable enable

​

//https://stackoverflow.com/questions/76441698/can-i-use-a-appsettings-json-record-for-jsonpropertyname-in-a-class-model

​

//References:

// https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-7.0

// https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.configuration.iconfiguration.item?view=dotnet-plat-ext-7.0#microsoft-extensions-configuration-iconfiguration-item(system-string)

// https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.configuration.iconfiguration?view=dotnet-plat-ext-7.0

// https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-7.0#configuration-keys-and-values

//  Hierarchical keys 

//     Within the Configuration API, a colon separator (:) works on all platforms.

// https://stackoverflow.com/questions/39231951/how-do-i-access-configuration-in-any-class-in-asp-net-core

// https://stackoverflow.com/questions/55790277/dependency-injection-not-working-for-iconfiguration-c-net-core

// https://pradeepl.com/blog/dotnet/configuration-in-a-net-core-console-application/

​

    [System.AttributeUsage(System.AttributeTargets.Property | System.AttributeTargets.Field, AllowMultiple = false, Inherited = true)]

    public sealed class JsonConfiguredPropertyNameAttribute : System.Attribute

    {

        public string Key { get; }

        public JsonConfiguredPropertyNameAttribute(string key) => this.Key = key;

    }

​

    public class PropertyNamesFromConfigurationContractResolver : DefaultContractResolver

    {

        readonly IConfiguration config;

        public PropertyNamesFromConfigurationContractResolver(IConfiguration config) => this.config = config ?? throw new ArgumentNullException(nameof(config));

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

        {

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

            if (member.GetCustomAttribute<JsonConfiguredPropertyNameAttribute>()?.Key is {} key)

                property.PropertyName = config[key] ?? property.PropertyName;

            return property;

        }   

    }

​

    public class Project {

        public Project(string projectName) => this.ProjectName = projectName; // Test to make sure this works with both mutable and immutable properties

        public string ProjectId { get; set; }

​

        [JsonConfiguredPropertyName("fieldConfig:projectNameField")]

        public string ProjectName { get; set; }

​

        [JsonConfiguredPropertyName("fieldConfig:projectDescriptionField")]

        public string ProjectDescription { get; set; }

​

        [JsonConfiguredPropertyName("fieldConfig:projectCreatorField")]

        public string ProjectCreator { get; set; }

    }

    class TestClass

    {

        public static void Test(IConfiguration config)

        {

            var inputJson = GetRequiredJson();

            var settings = new JsonSerializerSettings();

            settings.ContractResolver = new PropertyNamesFromConfigurationContractResolver(config)

            {

                // Add other properties as required, e.g.

                NamingStrategy = new CamelCaseNamingStrategy(),

            };

            // Add other options as required, e.g.

            settings.NullValueHandling = NullValueHandling.Ignore;

            var project = JsonConvert.DeserializeObject<Project>(inputJson, settings);

            var outputJson = JsonConvert.SerializeObject(project, Formatting.Indented, settings);

            Console.WriteLine(outputJson);

            Assert.That(JToken.DeepEquals(JToken.Parse(inputJson), JToken.Parse(outputJson)));

        }   

        static string GetRequiredJson() =>

            """

            {

                "fieldA_0001": "name",

                "fieldA_0002": "description",

                "fieldA_0003": "creator" 

            }

            """;

    }

​

    public class Program

    {

        static string GetJson() =>

            """

            {

                "fieldConfig": {

                    "projectNameField": "fieldA_0001",

                    "projectDescriptionField": "fieldA_0002",

                    "projectCreatorField": "fieldA_0003"

                }

            }

            """;

        public static void Main(string[] args)

        {

            Console.WriteLine("Environment version: {0} ({1}), {2}", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

            Console.WriteLine("System.Text.Json version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine();

​

            File.WriteAllText("appsettings.json", GetJson());

​

            IConfiguration config = new ConfigurationBuilder()

                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)

                .AddEnvironmentVariables()

                .AddCommandLine(args)

                .Build();           

            try

            {

                TestClass.Test(config);

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

            finally

            {

                File.Delete("appsettings.json");

            }

        }

    }

​