using System;
using System.Text.Json;
using System.Text.Json.Serialization;

// 自定義 DateTime 轉(zhuǎn)換器
public class CustomDateTimeConverter : JsonConverter<DateTime>
{
    private const string DateFormat = "yyyy-MM-dd";

    // 反序列化：JSON -> DateTime
    public override DateTime Read(
        ref Utf8JsonReader reader, 
        Type typeToConvert, 
        JsonSerializerOptions options)
    {
        // 處理 null 值
        if (reader.TokenType == JsonTokenType.Null)
            return default;

        // 讀取 JSON 字符串
        var dateString = reader.GetString();
        if (DateTime.TryParseExact(dateString, DateFormat, null, System.Globalization.DateTimeStyles.None, out var result))
        {
            return result;
        }

        throw new JsonException($"Invalid date format. Expected '{DateFormat}' but got '{dateString}'");
    }

    // 序列化：DateTime -> JSON
    public override void Write(
        Utf8JsonWriter writer, 
        DateTime value, 
        JsonSerializerOptions options)
    {
        // 格式化為指定格式
        writer.WriteStringValue(value.ToString(DateFormat));
    }
}

public class Person
{
    public string Name { get; set; }
    [JsonConverter(typeof(CustomDateTimeConverter))] // 綁定轉(zhuǎn)換器
    public DateTime Birthday { get; set; }
}

// 測試代碼
var person = new Person 
{ 
    Name = "Alice", 
    Birthday = new DateTime(2025, 7, 19) 
};

var options = new JsonSerializerOptions
{
    WriteIndented = true,
    Converters = { new CustomDateTimeConverter() } // 注冊全局轉(zhuǎn)換器
};

string json = JsonSerializer.Serialize(person, options);
Console.WriteLine(json); 
// 輸出: {"Name":"Alice","Birthday":"2025-07-19"}

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

// 工廠類：處理 List<T>
public class ListConverterFactory : JsonConverterFactory
{
    // 判斷是否支持當(dāng)前類型
    public override bool CanConvert(Type typeToConvert)
    {
        // 僅支持 List<T> 類型
        return typeToConvert.IsGenericType && 
               typeToConvert.GetGenericTypeDefinition() == typeof(List<>);
    }

    // 動(dòng)態(tài)創(chuàng)建轉(zhuǎn)換器
    public override JsonConverter CreateConverter(
        Type typeToConvert, 
        JsonSerializerOptions options)
    {
        // 獲取 T 的類型
        var genericType = typeToConvert.GetGenericArguments()[0];
        // 創(chuàng)建泛型轉(zhuǎn)換器實(shí)例
        return (JsonConverter)Activator.CreateInstance(
            typeof(ListConverter<>).MakeGenericType(genericType));
    }
}

// 泛型轉(zhuǎn)換器：處理 List<T>
public class ListConverter<T> : JsonConverter<List<T>>
{
    // 反序列化：JSON -> List<T>
    public override List<T> Read(
        ref Utf8JsonReader reader, 
        Type typeToConvert, 
        JsonSerializerOptions options)
    {
        if (reader.TokenType != JsonTokenType.StartArray)
            throw new JsonException("Expected start of array");

        var list = new List<T>();
        while (reader.Read())
        {
            if (reader.TokenType == JsonTokenType.EndArray)
                break;

            var item = JsonSerializer.Deserialize<T>(ref reader, options);
            list.Add(item);
        }

        return list;
    }

    // 序列化：List<T> -> JSON
    public override void Write(
        Utf8JsonWriter writer, 
        List<T> value, 
        JsonSerializerOptions options)
    {
        writer.WriteStartArray();
        foreach (var item in value)
        {
            JsonSerializer.Serialize(writer, item, options);
        }
        writer.WriteEndArray();
    }
}

public class Product
{
    public string Name { get; set; }
    public List<int> Ratings { get; set; }
}

// 注冊工廠轉(zhuǎn)換器
var options = new JsonSerializerOptions
{
    WriteIndented = true,
    Converters = { new ListConverterFactory() }
};

var product = new Product
{
    Name = "Laptop",
    Ratings = new List<int> { 5, 4, 5 }
};

string json = JsonSerializer.Serialize(product, options);
Console.WriteLine(json);
// 輸出: {"Name":"Laptop","Ratings":[5,4,5]}

{ "Price": "1.23E+08" }

{ "Price": 123000000 }

public class DecimalConverter : JsonConverter<decimal>
{
    public override decimal Read(
        ref Utf8JsonReader reader, 
        Type typeToConvert, 
        JsonSerializerOptions options)
    {
        // 解析 JSON 字符串為 decimal
        return decimal.Parse(reader.GetString()!);
    }

    public override void Write(
        Utf8JsonWriter writer, 
        decimal value, 
        JsonSerializerOptions options)
    {
        // 將 decimal 轉(zhuǎn)為固定格式的字符串
        writer.WriteStringValue(value.ToString("F2"));
    }
}

public class Product
{
    [JsonConverter(typeof(DecimalConverter))]
    public decimal Price { get; set; }
}

public class CustomConverter<T> : JsonConverter<T>
{
    public override T Read(
        ref Utf8JsonReader reader, 
        Type typeToConvert, 
        JsonSerializerOptions options)
    {
        // 實(shí)現(xiàn)反序列化邏輯
    }

    public override void Write(
        Utf8JsonWriter writer, 
        T value, 
        JsonSerializerOptions options)
    {
        // 實(shí)現(xiàn)序列化邏輯
    }
}

public class CustomConverterFactory : JsonConverterFactory
{
    public override bool CanConvert(Type typeToConvert)
    {
        // 判斷是否支持類型
    }

    public override JsonConverter CreateConverter(
        Type typeToConvert, 
        JsonSerializerOptions options)
    {
        // 動(dòng)態(tài)創(chuàng)建轉(zhuǎn)換器
    }
}