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?>
        {
            public override DateTime? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
                => string.IsNullOrEmpty(reader.GetString()) ? default : ParseDateTime(reader.GetString());

            public override void Write(Utf8JsonWriter writer, DateTime? value, JsonSerializerOptions options)
                => writer.WriteStringValue(value?.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.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;
            return null;
        }

        //******************************DOAN   JSON 转换器处理日期数组****************************************
        public class DateTimeArrayConverter : JsonConverter<DateTime>
        {
            public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            {
                if (reader.TokenType == JsonTokenType.String)
                {
                    if (DateTime.TryParse(reader.GetString(), out var date))
                    {
                        return date;
                    }
                }
                throw new JsonException("Invalid date format");
            }

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

        public class DateTimeNullableArrayConverter : JsonConverter<DateTime?[]>
        {
            public override DateTime?[] Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            {
                if (reader.TokenType != JsonTokenType.StartArray)
                {
                    throw new JsonException("Expected start of array.");
                }

                var dates = new List<DateTime?>();

                while (reader.Read())
                {
                    if (reader.TokenType == JsonTokenType.EndArray)
                    {
                        return dates.ToArray();
                    }

                    if (reader.TokenType == JsonTokenType.String)
                    {
                        var dateString = reader.GetString();
                        if (string.IsNullOrEmpty(dateString))
                        {
                            dates.Add(null);
                        }
                        else if (DateTime.TryParse(dateString, out var date))
                        {
                            dates.Add(date);
                        }
                        else
                        {
                            throw new JsonException($"Invalid date format: {dateString}");
                        }
                    }
                    else
                    {
                        throw new JsonException("Expected string value in array.");
                    }
                }

                throw new JsonException("Unexpected end of JSON.");
            }

            public override void Write(Utf8JsonWriter writer, DateTime?[] value, JsonSerializerOptions options)
            {
                writer.WriteStartArray();
                foreach (var date in value)
                {
                    if (date.HasValue)
                    {
                        writer.WriteStringValue(date.Value.ToString("yyyy-MM-dd HH:mm:ss"));
                    }
                    else
                    {
                        writer.WriteNullValue();
                    }
                }
                writer.WriteEndArray();
            }
        }
    }
}