using System;
using NewLife.Reflection;
using NewLife.Serialization;

namespace NewLife.Data
{
    /// <summary>数据包编码器接口</summary>
    public interface IPacketEncoder
    {
        /// <summary>数值转数据包</summary>
        /// <param name="value">数值对象</param>
        /// <returns></returns>
        Packet Encode(Object value);

        /// <summary>数据包转对象</summary>
        /// <param name="data">数据包</param>
        /// <param name="type">目标类型</param>
        /// <returns></returns>
        Object Decode(Packet data, Type type);

        /// <summary>数据包转对象</summary>
        /// <typeparam name="T">目标类型</typeparam>
        /// <param name="data">数据包</param>
        /// <returns></returns>
        public T Decode<T>(Packet data) => (T)Decode(data, typeof(T));
    }

    /// <summary>默认数据包编码器。基础类型直接转，复杂类型Json序列化</summary>
    public class DefaultPacketEncoder : IPacketEncoder
    {
        #region 属性
        /// <summary>解码出错时抛出异常。默认false不抛出异常，仅返回默认值</summary>
        public Boolean ThrowOnError { get; set; }
        #endregion

        /// <summary>数值转数据包</summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public virtual Packet Encode(Object value)
        {
            if (value == null) return Array.Empty<Byte>();

            if (value is Packet pk) return pk;
            if (value is Byte[] buf) return buf;
            if (value is IAccessor acc) return acc.ToPacket();

            var type = value.GetType();
            return (type.GetTypeCode()) switch
            {
                TypeCode.Object => value.ToJson().GetBytes(),
                TypeCode.String => (value as String).GetBytes(),
                TypeCode.DateTime => ((DateTime)value).ToString("yyyy-MM-dd HH:mm:ss").GetBytes(),
                _ => (value + "").GetBytes(),
            };
        }

        /// <summary>数据包转对象</summary>
        /// <param name="data"></param>
        /// <param name="type"></param>
        /// <returns></returns>
        public virtual Object Decode(Packet data, Type type)
        {
            try
            {
                if (type == typeof(Packet)) return data;
                if (type == typeof(Byte[])) return data.ReadBytes();
                if (type.As<IAccessor>()) return type.AccessorRead(data);

                var str = data.ToStr();
                if (type.GetTypeCode() == TypeCode.String) return str;
                if (type.GetTypeCode() != TypeCode.Object) return str.ChangeType(type);

                return str.ToJsonEntity(type);
            }
            catch
            {
                if (ThrowOnError) throw;

                return null;
            }
        }
    }
}