using Newtonsoft.Json.Serialization;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace LiveForum.Code.JsonConverterExtend;

public class CustomContractResolverf : CamelCasePropertyNamesContractResolver
{
    protected override IValueProvider CreateMemberValueProvider(MemberInfo member)
    {
        var valueProvider = base.CreateMemberValueProvider(member);

        if (member is PropertyInfo property)
        {
            // 处理字符串属性
            if (IsStringType(property.PropertyType))
            {
                return new StringValueProvider(valueProvider);
            }

            // 处理可空值类型（DateTime?, int?, bool? 等）
            if (IsNullableValueType(property.PropertyType))
            {
                return new NullableValueTypeProvider(valueProvider);
            }
        }

        return valueProvider;
    }

    private bool IsStringType(Type type)
    {
        return type == typeof(string) ||
               (type.IsGenericType &&
                type.GetGenericTypeDefinition() == typeof(Nullable<>) &&
                type.GetGenericArguments()[0] == typeof(string));
    }

    private bool IsNullableValueType(Type type)
    {
        return type.IsGenericType &&
               type.GetGenericTypeDefinition() == typeof(Nullable<>);
    }

    private class StringValueProvider : IValueProvider
    {
        private readonly IValueProvider _innerProvider;

        public StringValueProvider(IValueProvider innerProvider)
        {
            _innerProvider = innerProvider;
        }

        public void SetValue(object target, object value)
        {
            _innerProvider.SetValue(target, value);
        }

        public object GetValue(object target)
        {
            var value = _innerProvider.GetValue(target);
            return value ?? string.Empty;
        }
    }

    private class NullableValueTypeProvider : IValueProvider
    {
        private readonly IValueProvider _innerProvider;

        public NullableValueTypeProvider(IValueProvider innerProvider)
        {
            _innerProvider = innerProvider;
        }

        public void SetValue(object target, object value)
        {
            _innerProvider.SetValue(target, value);
        }

        public object GetValue(object target)
        {
            var value = _innerProvider.GetValue(target);
            return value ?? string.Empty;
        }
    }
}
public class CustomContractResolver : CamelCasePropertyNamesContractResolver
{
    protected override IValueProvider CreateMemberValueProvider(MemberInfo member)
    {
        var valueProvider = base.CreateMemberValueProvider(member);

        // 处理字符串属性（包括可空字符串）
        if (member is PropertyInfo property &&
            (property.PropertyType == typeof(string) ||
             (property.PropertyType.IsGenericType &&
              property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) &&
              property.PropertyType.GetGenericArguments()[0] == typeof(string))))
        {
            return new StringValueProvider(valueProvider);
        }

        return valueProvider;
    }

    private class StringValueProvider : IValueProvider
    {
        private readonly IValueProvider _innerProvider;

        public StringValueProvider(IValueProvider innerProvider)
        {
            _innerProvider = innerProvider;
        }

        public void SetValue(object target, object value)
        {
            _innerProvider.SetValue(target, value);
        }

        public object GetValue(object target)
        {
            var value = _innerProvider.GetValue(target);
            return value ?? string.Empty;
        }
    }
}