using System;
using System.Text.Json;

public class SnakeCaseNamingPolicy : JsonNamingPolicy
{
    public override string ConvertName(string name)
    {
        return string.IsNullOrEmpty(name) ? name : ToSnakeCase(name);
    }

    private string ToSnakeCase(string name)
    {
        var stringBuilder = new System.Text.StringBuilder();
        for (var i = 0; i < name.Length; i++)
        {
            if (char.IsUpper(name[i]))
            {
                if (i > 0)
                {
                    stringBuilder.Append('_');
                }
                stringBuilder.Append(char.ToLowerInvariant(name[i]));
            }
            else
            {
                stringBuilder.Append(name[i]);
            }
        }
        return stringBuilder.ToString();
    }
}