irc-netcore-api/IRaCIS.Core.API/_ServiceExtensions/NewtonsoftJson/JSONTimeZoneConverter.cs

using IRaCIS.Core.Domain.Share;
using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using System;
using System.Globalization;

namespace IRaCIS.Core.API
{
    /// <summary>
    /// 序列化，反序列化的时候，处理时间 时区转换
    /// </summary>
    public class JSONTimeZoneConverter(IHttpContextAccessor _httpContextAccessor) : DateTimeConverterBase
    {

        private TimeZoneInfo _clientTimeZone;

        private string _dateFormat;



        public override bool CanConvert(Type objectType)
        {
            #region 设置语言格式化方式，放在构造函数里面做不到动态切换


            var isEn_US = CultureInfo.CurrentCulture.Name == StaticData.CultureInfo.en_US;

            if (!isEn_US)
            {
                // Chinese date format
                _dateFormat = "yyyy-MM-dd HH:mm:ss";
            }
            else
            {
                // Default or English date format
                //_dateFormat = "MM/dd/yyyy HH:mm:ss";

                _dateFormat = "yyyy-MM-dd HH:mm:ss";
            }

            #endregion

            #region 获取当前请求的客户端时区

            //var timeZoneId = "Etc/UTC";
            var timeZoneId = "Asia/Shanghai";
            var timeZoneIdHeader = _httpContextAccessor?.HttpContext?.Request?.Headers["TimeZoneId"];

            if (timeZoneIdHeader is not null && !string.IsNullOrEmpty(timeZoneIdHeader.Value))
            {
                timeZoneId = timeZoneIdHeader.Value;
            }

            _clientTimeZone = TimeZoneInfo.FindSystemTimeZoneById(timeZoneId);

            #endregion


            // 仅支持 DateTime 类型的转换
            return objectType == typeof(DateTime) || objectType == typeof(DateTime?);

        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            if (reader.Value == null)
            {
                return null;
            }

            DateTime dateTime;

            // 2. 检查目标类型是否可空
            bool isNullable = objectType == typeof(DateTime?);

            var canConvert = DateTime.TryParse(reader.Value?.ToString(), out dateTime);


            if (isNullable == false && canConvert == false)
            {

                throw new JsonSerializationException($"Could not convert string to DateTime: {reader.Value} Path {reader.Path}"); 
            }
            else
            {
                if (canConvert == false)
                {
                    return null;
                }
            }

            ////如果前端传递带时区的，那么转换会报错，需要DateTimeKind.Unspecified
            //dateTime = DateTime.SpecifyKind(dateTime, DateTimeKind.Unspecified);

            // 将客户端时间转换为服务器时区的时间
            var serverZoneTime = TimeZoneInfo.ConvertTime(dateTime, _clientTimeZone, TimeZoneInfo.Local);

            return serverZoneTime;



        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            DateTime? nullableDateTime = value as DateTime?;

            if (nullableDateTime != null && nullableDateTime.HasValue)
            {
                //第一个参数默认使用系统本地时区 也就是应用服务器的时区
                DateTime clientZoneTime = TimeZoneInfo.ConvertTime(nullableDateTime.Value, _clientTimeZone);


                //// 最简单的方式：创建 DateTimeOffset
                //DateTimeOffset dateTimeOffset = new DateTimeOffset(clientZoneTime, _clientTimeZone.GetUtcOffset(clientZoneTime));
                //writer.WriteValue(dateTimeOffset.ToString("yyyy-MM-dd HH:mm:sszzz"));

                writer.WriteValue(clientZoneTime.ToString(_dateFormat));
            }
            else
            {
                writer.WriteNull();
            }
        }

    }


    public class DateOnlyUniversalJsonConverter : JsonConverter
    {
        private readonly string _format;

        public DateOnlyUniversalJsonConverter(string format = "yyyy-MM-dd")
        {
            _format = format;
        }

        public override bool CanConvert(Type objectType)
        {
            return objectType == typeof(DateOnly) || objectType == typeof(DateOnly?);
        }

        public override void WriteJson(JsonWriter writer, object? value, JsonSerializer serializer)
        {
            if (value == null)
            {
                writer.WriteValue(""); // null -> 空字符串
                return;
            }

            var date = (DateOnly)value;
            if (date == default)
            {
                writer.WriteValue(""); // default(DateOnly) -> 空字符串
            }
            else
            {
                writer.WriteValue(date.ToString(_format));
            }
        }

        public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
        {
            var str = reader.TokenType == JsonToken.Null ? null : reader.Value?.ToString();

            if (string.IsNullOrWhiteSpace(str) || !DateOnly.TryParse(str, out var date))
            {
                return objectType == typeof(DateOnly?) ? null : default(DateOnly);
            }

            return date;
        }
    }

    #region 废弃

    public class MyDateTimeConverter : JsonConverter<DateTime>
    {
        public override DateTime ReadJson(JsonReader reader, Type objectType, DateTime existingValue, bool hasExistingValue, JsonSerializer serializer)
        {
            return reader.ReadAsDateTime().Value;
        }

        public override void WriteJson(JsonWriter writer, DateTime value, JsonSerializer serializer)
        {
            var isEn_US = CultureInfo.CurrentCulture.Name == StaticData.CultureInfo.en_US;

            string dateFormat;
            if (!isEn_US)
            {
                // Chinese date format
                dateFormat = "yyyy-MM-dd HH:mm:ss";
            }
            else
            {
                // Default or English date format
                dateFormat = "MM/dd/yyyy HH:mm:ss";
            }

            writer.WriteValue(value.ToString(dateFormat));

        }
    }

    public class MyNullableDateTimeConverter : JsonConverter<DateTime?>
    {
        public override DateTime? ReadJson(JsonReader reader, Type objectType, DateTime? existingValue, bool hasExistingValue, JsonSerializer serializer)
        {
            var val = reader.ReadAsDateTime();
            return val;
        }

        public override void WriteJson(JsonWriter writer, DateTime? value, JsonSerializer serializer)
        {
            var isEn_US = CultureInfo.CurrentCulture.Name == StaticData.CultureInfo.en_US;

            string dateFormat;
            if (!isEn_US)
            {
                // Chinese date format
                dateFormat = "yyyy-MM-dd HH:mm:ss";
            }
            else
            {
                // Default or English date format
                dateFormat = "MM/dd/yyyy HH:mm:ss";
            }

            if (value.HasValue)
            {
                writer.WriteValue(value.Value.ToString(dateFormat));

            }
            else
            {
                writer.WriteValue(default(DateTime?));
            }

        }
    }

    #endregion
}