using System;
using System.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace Infrastructure.Converter
{
    public class JsonConverterUtil
    {
        /// <summary>
        /// 你提供的转换器是针对单个 DateTime 或 DateTime? 的，而日期数组是一个集合类型（如 DateTime[] 或 List<DateTime>）。JSON 转换器需要明确知道如何处理集合中的每个元素。
        /// </summary>
        public class DateTimeNullConverter : JsonConverter<DateTime?>
        {
            //该方法用于将 JSON 字符串反序列化为 DateTime? 类型的值。
            public override DateTime? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
                => string.IsNullOrEmpty(reader.GetString()) ? default : ParseDateTime(reader.GetString());

            //方法用于将 DateTime? 类型的值序列化为 JSON 字符串
            public override void Write(Utf8JsonWriter writer, DateTime? value, JsonSerializerOptions options)
                => writer.WriteStringValue(value?.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss"));
        }

        public class DateTimeConverter : JsonConverter<DateTime>
        {
            public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            {
                var dateTime = ParseDateTime(reader.GetString());
                return dateTime == null ? DateTime.MinValue : dateTime.Value;
            }

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

        public static DateTime? ParseDateTime(string dateStr)
        {
            if (System.Text.RegularExpressions.Regex.IsMatch(dateStr, @"^\d{4}[/-]") && DateTime.TryParse(dateStr, null, System.Globalization.DateTimeStyles.AssumeLocal, out var dateVal))
                return dateVal.ToLocalTime();
            return null;
        }

        //******************************DOAN   JSON 转换器处理日期数组****************************************
        public class DateTimeArrayConverter : JsonConverter<IEnumerable<DateTime>>
        {
            public override IEnumerable<DateTime> Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            {
                if (reader.TokenType == JsonTokenType.StartArray)
                {
                    var list = new List<DateTime>();
                    while (reader.Read() && reader.TokenType != JsonTokenType.EndArray)
                    {
                        if (reader.TokenType == JsonTokenType.String)
                        {
                            var dateTime = ParseDateTime(reader.GetString());
                            if (dateTime != null)
                            {
                                list.Add(dateTime.Value.ToLocalTime()); // 将UTC时间转为本地时间
                            }
                        }
                    }
                    return list;
                }
                throw new JsonException();
            }

            public override void Write(Utf8JsonWriter writer, IEnumerable<DateTime> value, JsonSerializerOptions options)
            {
                writer.WriteStartArray();
                foreach (var date in value)
                {
                    writer.WriteStringValue(date.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss"));
                }
                writer.WriteEndArray();
            }

            private static DateTime? ParseDateTime(string dateStr)
            {
                if (!string.IsNullOrEmpty(dateStr) && DateTime.TryParse(dateStr, out var dateVal))
                {
                    return dateVal; // 假设输入的已经是UTC时间
                }
                return null;
            }
        }
    }
}