using System.Collections;
using System.Collections.Specialized;
using NewLife.Data;
using NewLife.Model;
using NewLife.Reflection;

namespace NewLife.Serialization;

/// <summary>Json读取器</summary>
/// <remarks>
/// 文档 https://newlifex.com/core/json
/// </remarks>
public class JsonReader
{
    #region 属性
    /// <summary>是否使用UTC时间</summary>
    public Boolean UseUTCDateTime { get; set; }

    /// <summary>服务提供者</summary>
    public IServiceProvider Provider { get; set; } = ObjectContainer.Provider;
    #endregion

    #region 转换方法
    /// <summary>读取Json到指定类型</summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="json"></param>
    /// <returns></returns>
    public T Read<T>(String json) => (T)Read(json, typeof(T));

    /// <summary>读取Json到指定类型</summary>
    /// <param name="json"></param>
    /// <param name="type"></param>
    /// <returns></returns>
    public Object Read(String json, Type type)
    {
        // 解码得到字典或列表
        var obj = new JsonParser(json).Decode();
        if (obj == null) return null;

        return ToObject(obj, type, null);
    }

    /// <summary>Json字典或列表转为具体类型对象</summary>
    /// <param name="jobj">Json对象</param>
    /// <param name="type">模板类型</param>
    /// <param name="target">目标对象</param>
    /// <returns></returns>
    public Object ToObject(Object jobj, Type type, Object target)
    {
        if (type == null && target != null) type = target.GetType();

        if (jobj == null || type.IsAssignableFrom(jobj.GetType())) return jobj;

        // Json对象是字典，目标类型可以是字典或复杂对象
        if (jobj is IDictionary<String, Object> vdic)
        {
            if (type.IsDictionary())
                return ParseDictionary(vdic, type, target as IDictionary);
            else
                return ParseObject(vdic, type, target);
        }

        // Json对象是列表，目标类型只能是列表或数组
        if (jobj is IList<Object> vlist)
        {
            if (type.IsList()) return ParseList(vlist, type, target);
            if (type.IsArray) return ParseArray(vlist, type, target);
            // 复杂键值的字典，也可能保存为Json数组
            if (type.IsDictionary()) return CreateDictionary(vlist, type, target);

            if (vlist.Count == 0) return target;

            throw new InvalidCastException($"Json数组无法转为目标类型[{type.FullName}]，仅支持数组和List<T>/IList<T>");
        }

        if (type != null && jobj.GetType() != type)
            return ChangeType(jobj, type);

        return jobj;
    }
    #endregion

    #region 复杂类型
    /// <summary>转为泛型列表</summary>
    /// <param name="vlist"></param>
    /// <param name="type"></param>
    /// <param name="target">目标对象</param>
    /// <returns></returns>
    private IList ParseList(IList<Object> vlist, Type type, Object target)
    {
        var elmType = type.GetGenericArguments().FirstOrDefault();

        // 处理一下type是IList<>的情况
        if (type.IsInterface) type = typeof(List<>).MakeGenericType(elmType);

        // 创建列表
        var list = (target ?? type.CreateInstance()) as IList;
        foreach (var item in vlist)
        {
            if (item == null) continue;

            var val = ToObject(item, elmType, null);
            list.Add(val);
        }
        return list;
    }

    /// <summary>转为数组</summary>
    /// <param name="list"></param>
    /// <param name="type"></param>
    /// <param name="target">目标对象</param>
    /// <returns></returns>
    private Array ParseArray(IList<Object> list, Type type, Object target)
    {
        var elmType = type?.GetElementTypeEx();
        if (elmType == null) elmType = typeof(Object);

        // 如果元素组长度不足，则创建新数组。主要是某些成员使用数组类型，然后使用[]初始化，导致数组长度为零
        if (target is not Array arr || arr.Length < list.Count) arr = Array.CreateInstance(elmType, list.Count);

        // 如果源数组有值，则最大只能创建源数组那么多项，抛弃多余项
        for (var i = 0; i < list.Count && i < arr.Length; i++)
        {
            var item = list[i];
            if (item == null) continue;

            var val = ToObject(item, elmType, arr.GetValue(i));
            arr.SetValue(val, i);
        }

        return arr;
    }

    /// <summary>转为泛型字典</summary>
    /// <param name="dic"></param>
    /// <param name="type"></param>
    /// <param name="target">目标对象</param>
    /// <returns></returns>
    private IDictionary ParseDictionary(IDictionary<String, Object> dic, Type type, IDictionary target)
    {
        var types = type.GetGenericArguments();

        if (target == null)
        {
            // 处理一下type是Dictionary<,>的情况
            if (type.IsInterface) type = typeof(Dictionary<,>).MakeGenericType(types[0], types[1]);

            target = type.CreateInstance() as IDictionary;
        }
        foreach (var kv in dic)
        {
            var key = ToObject(kv.Key, types[0], null);
            var val = ToObject(kv.Value, types[1], null);
            target.Add(key, val);
        }

        return target;
    }

    private readonly Dictionary<Object, Int32> _circobj = new();
    private readonly Dictionary<Int32, Object> _cirrev = new();
    /// <summary>字典转复杂对象，反射属性赋值</summary>
    /// <param name="dic"></param>
    /// <param name="type"></param>
    /// <param name="target">目标对象</param>
    /// <returns></returns>
    internal Object ParseObject(IDictionary<String, Object> dic, Type type, Object target)
    {
        if (type == typeof(NameValueCollection)) return CreateNV(dic);
        if (type == typeof(StringDictionary)) return CreateSD(dic);
        if (type == typeof(Object)) return dic;

        target ??= Provider.GetService(type) ?? Provider.CreateInstance(type) ?? type.CreateInstance();
        if (target == null) return null;

        if (type.IsDictionary()) return CreateDic(dic, type, target);

        if (!_circobj.TryGetValue(target, out var circount))
        {
            circount = _circobj.Count + 1;
            _circobj.Add(target, circount);
            _cirrev.Add(circount, target);
        }

        // 扩展属性

        // 遍历所有可用于序列化的属性
        var props = target.GetType().GetProperties(true).ToDictionary(e => SerialHelper.GetName(e), e => e);
        foreach (var item in dic)
        {
            var v = item.Value;
            if (v == null) continue;

            if (!props.TryGetValue(item.Key, out var pi))
            {
                // 可能有小写
                pi = props.Values.FirstOrDefault(e => e.Name.EqualIgnoreCase(item.Key));
                if (pi == null)
                {
                    // 可能有扩展属性
                    if (target is IExtend ext) ext[item.Key] = item.Value;

                    continue;
                }
            }
            if (!pi.CanWrite) continue;

            var pt = pi.PropertyType;
            if (pt.IsBaseType())
                target.SetValue(pi, ChangeType(v, pt));
            else
            {
                var orig = target.GetValue(pi);
                var val = ToObject(v, pt, orig);
                if (val != orig)
                {
                    if (target is IModel dst)
                        dst[pi.Name] = val;
                    else
                        target.SetValue(pi, val);
                }
            }
        }
        return target;
    }
    #endregion

    #region 辅助
    private Object ChangeType(Object value, Type type)
    {
        // 支持可空类型
        if (type.IsGenericType && type.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
        {
            if (value == null) return value;

            type = type.GetGenericArguments()[0];
        }

        if (type == typeof(Int32)) return value.ToInt();
        if (type == typeof(Int64)) return value.ToLong();
        if (type == typeof(String)) return value + "";
        if (type == typeof(Type) && value is String str) return Type.GetType(str) ?? Type.GetType("System." + str);

        if (type.IsEnum) return Enum.Parse(type, value + "");
        if (type == typeof(DateTime)) return CreateDateTime(value);

        if (type == typeof(DateTimeOffset)) return value.ToDateTimeOffset();

        if (type == typeof(Guid)) return new Guid((String)value);

        if (type == typeof(Byte[]))
        {
            if (value is Byte[] v) return v;

            return Convert.FromBase64String(value + "");
        }

        if (type == typeof(Packet))
        {
            if (value is Packet v) return v;

            return new Packet(Convert.FromBase64String(value + ""));
        }

        if (type == typeof(TimeSpan)) return TimeSpan.Parse(value + "");

        if (value is String str2) return str2.ChangeType(type);
        if (type.IsBaseType()) return value.ChangeType(type);

        return null;
    }

    private StringDictionary CreateSD(IDictionary<String, Object> dic)
    {
        var nv = new StringDictionary();
        foreach (var item in dic)
            nv.Add(item.Key, (String)item.Value);

        return nv;
    }

    private NameValueCollection CreateNV(IDictionary<String, Object> dic)
    {
        var nv = new NameValueCollection();
        foreach (var item in dic)
            nv.Add(item.Key, (String)item.Value);

        return nv;
    }

    private IDictionary CreateDic(IDictionary<String, Object> dic, Type type, Object obj)
    {
        var nv = obj as IDictionary;
        if (type.IsGenericType && type.GetGenericArguments().Length >= 2)
        {
            var tval = type.GetGenericArguments()[1];
            foreach (var item in dic)
                nv.Add(item.Key, item.Value.ChangeType(tval));
        }
        else
        {
            foreach (var item in dic)
                nv.Add(item.Key, item.Value);
        }

        return nv;
    }

    private Int32 CreateInteger(String str, Int32 index, Int32 count)
    {
        var num = 0;
        var neg = false;
        for (var x = 0; x < count; x++, index++)
        {
            var cc = str[index];

            if (cc == '-')
                neg = true;
            else if (cc == '+')
                neg = false;
            else
            {
                num *= 10;
                num += cc - '0';
            }
        }
        if (neg) num = -num;

        return num;
    }

    /// <summary>创建时间</summary>
    /// <param name="value"></param>
    /// <returns></returns>
    private DateTime CreateDateTime(Object value)
    {
        if (value is DateTime) return (DateTime)value;
        if (value is Int64 or Int32)
        {
            var dt = value.ToDateTime();
            if (UseUTCDateTime) dt = dt.ToUniversalTime();
            return dt;
        }

        //用于解决奇葩json中时间字段使用了utc时间戳，还是用双引号包裹起来的情况。
        if (value is String str)
        {
            if (str.IsNullOrEmpty()) return DateTime.MinValue;

            if (Int64.TryParse(str, out var result) && result > 0)
            {
                var sdt = result.ToDateTime();
                if (UseUTCDateTime) sdt = sdt.ToUniversalTime();
                return sdt;
            }

            // 尝试直转时间
            var dt = str.ToDateTime();
            if (dt.Year > 1) return UseUTCDateTime ? dt.ToUniversalTime() : dt;

            var utc = false;

            var year = 0;
            var month = 0;
            var day = 0;
            var hour = 0;
            var min = 0;
            var sec = 0;
            var ms = 0;

            year = CreateInteger(str, 0, 4);
            month = CreateInteger(str, 5, 2);
            day = CreateInteger(str, 8, 2);
            if (str.Length >= 19)
            {
                hour = CreateInteger(str, 11, 2);
                min = CreateInteger(str, 14, 2);
                sec = CreateInteger(str, 17, 2);
                if (str.Length > 21 && str[19] == '.')
                    ms = CreateInteger(str, 20, 3);

                if (str[str.Length - 1] == 'Z' || str.EndsWithIgnoreCase("UTC")) utc = true;
            }

            if (!UseUTCDateTime && !utc)
                return new DateTime(year, month, day, hour, min, sec, ms);
            else
                return new DateTime(year, month, day, hour, min, sec, ms, DateTimeKind.Utc).ToLocalTime();
        }

        return DateTime.MinValue;
    }

    private Object CreateDictionary(IList<Object> list, Type type, Object target)
    {
        var types = type.GetGenericArguments();
        var dic = (target ?? type.CreateInstance()) as IDictionary;
        foreach (IDictionary<String, Object> values in list)
        {
            var key = ToObject(values["k"], types[0], null);
            var val = ToObject(values["v"], types[1], null);
            dic.Add(key, val);
        }

        return dic;
    }
    #endregion
}