using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading.Tasks;

namespace Elight.Utility
{
    /// <summary>
    /// 自定义 NullableConverter 解决可为空类型字段入参“”空字符触发转换异常问题
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class NullableConverter<T> : JsonConverter<T?> where T:struct
    {
        public override T? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType == JsonTokenType.String)
            {
                if (string.IsNullOrEmpty(reader.GetString()) || string.IsNullOrWhiteSpace(reader.GetString()))
                {
                    return null;
                }
            }
            return JsonSerializer.Deserialize<T>(ref reader, options);
        }


        public override void Write(Utf8JsonWriter writer, T? value, JsonSerializerOptions options)
        {
            JsonSerializer.Serialize(writer, value!.Value, options);
        }

    }

    public class DateTimeNullableConverter : JsonConverter<DateTime?>
    {
        public override DateTime? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType == JsonTokenType.String)
            {
                if (DateTime.TryParse(reader.GetString(), out DateTime date)) return date;
                return default(DateTime?);

            }
            return reader.GetDateTime();
        }

        public override void Write(Utf8JsonWriter writer, DateTime? value, JsonSerializerOptions options)
        {
            writer.WriteStringValue(value?.ToString("yyyy-MM-dd HH:mm:ss"));
        }
    }
}