using System.Collections;
using NewLife.Reflection;

namespace NewLife.Serialization;

/// <summary>Json序列化字典</summary>
public class JsonDictionary : JsonHandlerBase
{
    /// <summary>初始化</summary>
    public JsonDictionary()
    {
        // 优先级
        Priority = 20;
    }

    /// <summary>写入</summary>
    /// <param name="value"></param>
    /// <param name="type"></param>
    /// <returns></returns>
    public override Boolean Write(Object? value, Type type)
    {
        if (value is not IDictionary dic) return false;

        Host.Write("{");

        // 循环写入数据
        foreach (var item in dic)
        {
            if (item is DictionaryEntry de)
            {
                Host.Write(de.Key);
                Host.Write(de.Value);
            }
        }

        Host.Write("}");

        return true;
    }

    /// <summary>读取</summary>
    /// <param name="type"></param>
    /// <param name="value"></param>
    /// <returns></returns>
    public override Boolean TryRead(Type type, ref Object? value)
    {
        if (!type.As<IDictionary>() && !type.As(typeof(IDictionary<,>))) return false;

        // 先读取
        if (!Host.Read("{")) return false;

        // 子元素类型
        var elmType = type.GetElementTypeEx();
        if (elmType == null) throw new ArgumentNullException(nameof(elmType));

        var list = typeof(IList<>).MakeGenericType(elmType).CreateInstance() as IList;
        if (list == null) throw new ArgumentOutOfRangeException(nameof(elmType));

        while (!Host.Read("}"))
        {
            Object? obj = null;
            if (!Host.TryRead(elmType, ref obj)) return false;

            list.Add(obj);
        }

        // 数组的创建比较特别
        if (type.As<Array>())
        {
            value = Array.CreateInstance(elmType, list.Count);
            list.CopyTo((Array)value, 0);
        }
        else
            value = list;

        return true;
    }
}