using System;
using System.Net;

namespace ProtoDataBuff
{

    //常量数据
    public class Constants
    {
        //消息：数据总长度(4byte) + 数据类型(2byte) + 数据(N byte)
        public static int HEAD_DATA_LEN = 4;
        public static int HEAD_TYPE_LEN = 2;
        public static int HEAD_LEN//6byte
        {
            get { return HEAD_DATA_LEN + HEAD_TYPE_LEN; }
        }
    }

    /// <summary>
    /// 网络数据结构
    /// </summary>
    [Serializable]
    public struct sSocketData
    {
        public Int32 PackLen;
        //public UInt32 TS;
        public eProtocalCommand _protocallType;
        public byte[] _data;

        /// <summary>
        /// 网络结构转数据
        /// </summary>
        /// <param name="tmpSocketData"></param>
        /// <returns></returns>
        public byte[] ToBytes()
        {
            byte[] _tmpBuff = new byte[PackLen];
            byte[] _tmpBuffLength = BitConverter.GetBytes(IPAddress.HostToNetworkOrder(PackLen));
            byte[] _tmpDataType = BitConverter.GetBytes(IPAddress.HostToNetworkOrder((Int16)_protocallType));

            Array.Copy(_tmpBuffLength, 0, _tmpBuff, 0, Constants.HEAD_DATA_LEN);                    //缓存总长度
            Array.Copy(_tmpDataType, 0, _tmpBuff, Constants.HEAD_DATA_LEN, Constants.HEAD_TYPE_LEN);//协议类型
            Array.Copy(_data, 0, _tmpBuff, Constants.HEAD_LEN, DataLen());                          //协议数据

            return _tmpBuff;
        }

        public int DataLen() => _data.Length;
        /// <summary>
        /// 数据转网络结构
        /// </summary>
        /// <param name="_protocalType"></param>
        /// <param name="_data"></param>
        /// <returns></returns>
        public static sSocketData FromBytes(eProtocalCommand _protocalType, byte[] _data)
        {
            sSocketData tmpSocketData = new();
            tmpSocketData.PackLen = Constants.HEAD_LEN + _data.Length;
            //  tmpSocketData._dataLength = _data.Length;
            tmpSocketData._protocallType = _protocalType;
            tmpSocketData._data = _data;
            return tmpSocketData;
        }
    }

    /// <summary>
    /// 网络数据缓存器，//自动大小数据缓存器
    /// </summary>
    [Serializable]
    public class DataBuffer
    {
        private int _minBuffLen;
        private byte[] _buff;
        private int _curBuffPosition;
        private int _buffLength = 0;
        private int _dataLength;
        private UInt16 _protocalType;


        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="_minBuffLen">最小缓冲区大小</param>
        public DataBuffer(int _minBuffLen = 1024)
        {
            if (_minBuffLen <= 0)
            {
                this._minBuffLen = 1024;
            }
            else
            {
                this._minBuffLen = _minBuffLen;
            }
            _buff = new byte[this._minBuffLen];
        }

        /// <summary>
        /// 添加缓存数据
        /// </summary>
        /// <param name="_data"></param>
        /// <param name="_dataLen"></param>
        public void AddBuffer(byte[] _data, int _dataLen)
        {
            if (_dataLen > _buff.Length - _curBuffPosition)//超过当前缓存
            {
                byte[] _tmpBuff = new byte[_curBuffPosition + _dataLen];
                Array.Copy(_buff, 0, _tmpBuff, 0, _curBuffPosition);
                Array.Copy(_data, 0, _tmpBuff, _curBuffPosition, _dataLen);
                _buff = _tmpBuff;
                _tmpBuff = null;
            }
            else
            {
                Array.Copy(_data, 0, _buff, _curBuffPosition, _dataLen);
            }
            _curBuffPosition += _dataLen;//修改当前数据标记
        }

        /// <summary>
        /// 更新数据长度
        /// </summary>
        public void UpdateDataLength()
        {
            if (_dataLength == 0 && _curBuffPosition >= Constants.HEAD_LEN)
            {
                byte[] tmpDataLen = new byte[Constants.HEAD_DATA_LEN];
                Array.Copy(_buff, 0, tmpDataLen, 0, Constants.HEAD_DATA_LEN);
                _buffLength =IPAddress.NetworkToHostOrder( BitConverter.ToInt32(tmpDataLen, 0));

                byte[] tmpProtocalType = new byte[Constants.HEAD_TYPE_LEN];
                Array.Copy(_buff, Constants.HEAD_DATA_LEN, tmpProtocalType, 0, Constants.HEAD_TYPE_LEN);
                _protocalType = (ushort)IPAddress.NetworkToHostOrder( BitConverter.ToInt16(tmpProtocalType, 0));

                _dataLength = _buffLength - Constants.HEAD_LEN;
            }
        }

        /// <summary>
        /// 获取一条可用数据，返回值标记是否有数据
        /// </summary>
        /// <param name="_tmpSocketData"></param>
        /// <returns></returns>
        public bool GetData(out sSocketData _tmpSocketData)
        {
            _tmpSocketData = new sSocketData();

            if (_buffLength <= 0)
            {
                UpdateDataLength();
            }

            if (_buffLength > 0 && _curBuffPosition >= _buffLength)
            {
                _tmpSocketData.PackLen = _buffLength;
                //_tmpSocketData._dataLength = _dataLength;
                _tmpSocketData._protocallType = (eProtocalCommand)_protocalType;
                _tmpSocketData._data = new byte[_dataLength];
                Array.Copy(_buff, Constants.HEAD_LEN, _tmpSocketData._data, 0, _dataLength);
                _curBuffPosition -= _buffLength;
                byte[] _tmpBuff = new byte[_curBuffPosition < _minBuffLen ? _minBuffLen : _curBuffPosition];
                Array.Copy(_buff, _buffLength, _tmpBuff, 0, _curBuffPosition);
                _buff = _tmpBuff;


                _buffLength = 0;
                _dataLength = 0;
                _protocalType = 0;
                return true;
            }
            return false;
        }

    }
}