using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using NewLife.Data;
using NewLife.Messaging;
using NewLife.Model;

namespace NewLife.Net.Handlers
{
    /// <summary>标准网络封包。头部4字节定长</summary>
    public class StandardCodec : MessageCodec<IMessage>
    {
        private Int32 _gid;

        /// <summary>写入数据</summary>
        /// <param name="context"></param>
        /// <param name="message"></param>
        /// <returns></returns>
        public override Object Write(IHandlerContext context, Object message)
        {
            if (UserPacket && message is Packet pk)
                message = new DefaultMessage { Payload = pk, Sequence = (Byte)Interlocked.Increment(ref _gid) };
            else if (message is DefaultMessage msg && !msg.Reply && msg.Sequence == 0)
                msg.Sequence = (Byte)Interlocked.Increment(ref _gid);

            return base.Write(context, message);
        }

        /// <summary>加入队列</summary>
        /// <param name="context"></param>
        /// <param name="msg"></param>
        /// <returns></returns>
        protected override void AddToQueue(IHandlerContext context, IMessage msg)
        {
            if (!msg.Reply) base.AddToQueue(context, msg);
        }

        /// <summary>解码</summary>
        /// <param name="context"></param>
        /// <param name="pk"></param>
        /// <returns></returns>
        protected override IList<IMessage> Decode(IHandlerContext context, Packet pk)
        {
            var ss = context.Owner as IExtend;
            if (ss["Codec"] is not PacketCodec pc)
            {
                ss["Codec"] = pc = new PacketCodec
                {
                    GetLength = DefaultMessage.GetLength,
                    Tracer = (context.Owner as ISocket)?.Tracer
                };
            }

            var pks = pc.Parse(pk);
            var list = pks.Select(e =>
            {
                var msg = new DefaultMessage();
                if (!msg.Read(e)) return null;

                return msg as IMessage;
            }).ToList();

            return list;
        }

        /// <summary>是否匹配响应</summary>
        /// <param name="request"></param>
        /// <param name="response"></param>
        /// <returns></returns>
        protected override Boolean IsMatch(Object request, Object response)
        {
            return request is DefaultMessage req &&
                response is DefaultMessage res &&
                req.Sequence == res.Sequence;
        }

        /// <summary>连接关闭时，清空粘包编码器</summary>
        /// <param name="context"></param>
        /// <param name="reason"></param>
        /// <returns></returns>
        public override Boolean Close(IHandlerContext context, String reason)
        {
            if (context.Owner is IExtend ss) ss["Codec"] = null;

            return base.Close(context, reason);
        }
    }
}