modules/project/Aki.Custom/Models/DifficultyInfo.cs

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Reflection;

namespace Aki.Custom.Models
{
    [Serializable]
    public struct DifficultyInfo
    {
        public Dictionary<string, object> this[string key]
        {
            get
            {
                switch (key)
                {
                    case "easy":
                        return easy;
                    case "hard":
                        return hard;
                    case "impossible":
                        return impossible;
                    case "normal":
                        return normal;
                    default:
                        throw new ArgumentException($"Difficulty '{key}' does not exist in DifficultyInfo.");
                }
            }
        }

        [JsonProperty("easy")]
        public Dictionary<string, object> easy;

        [JsonProperty("hard")]
        public Dictionary<string, object> hard;

        [JsonProperty("impossible")]
        public Dictionary<string, object> impossible;

        [JsonProperty("normal")]
        public Dictionary<string, object> normal;
    }
}