using System;

namespace XGame.Framework.Network
{
    public class BytesReader : IBytesReader
    {
        private enum ReadState
        {
            readHead = 0,
            readBody = 1,
            closed = 2
        }
        private const int BUFFER_SIZE = ushort.MaxValue;
        //private const int Length_Heart = 2;
        //private const int Length_Response = 10;//modify
        //private const int Length_Push = 6;
        private ReadState _readState = ReadState.readHead;
        private int _bytesOffset = 0;
        private byte[] _recvBytes = new byte[BUFFER_SIZE];
        private int _msgLength = 0;
        private int _headLength = 0;
        public IMsgReceiver _receiver;

        public BytesReader(IMsgReceiver receiver)
        {
            _receiver = receiver;
        }

        public void Read(byte[] bytes, int offset, int length)
        {
            while (offset <= length)
            {
                if (_readState == ReadState.readHead)
                {
                    int len = length - offset;//数据长度
                    if ((_bytesOffset == 0 && len >= 2) || _bytesOffset == 1)//需要知道头部长度的情况
                    {
                        _headLength = GetHeadLen(bytes[_bytesOffset == 0 ? 1 + offset : 0 + offset]);
                        if (_headLength != NetDefine.HEAD_LENGTH_PUSH && _headLength != NetDefine.HEAD_LENGTH_REQUEST && _headLength != NetDefine.HEAD_LENGTH_HEART)
                        {
                            Log.Error($"[Net] 消息Head长度错误，HeadLength={_headLength}");
                            Reset();
                            return;
                        }
                    }

                    //只有知道头部长度才知道是否完整
                    if (_headLength != 0 && len >= _headLength - _bytesOffset)//说明头部完整
                    {
                        WriteBytes(bytes, offset, _recvBytes, _bytesOffset, _headLength - _bytesOffset);

                        _readState = ReadState.readBody;
                        offset += _headLength - _bytesOffset;
                        _bytesOffset = _headLength;
                        if (_headLength != NetDefine.HEAD_LENGTH_HEART)
                        {
                            _msgLength = GetMsgLen(_bytesOffset, _recvBytes);//获取消息长度
                        }

                        if (offset <= length)
                        {
                            //还有数据就接着读
                            continue;
                        }
                    }
                    else
                    {
                        //能走到这里说明头部不完整 先把byte记下 等下一条
                        WriteBytes(bytes, offset, _recvBytes, _bytesOffset, len);
                        _bytesOffset += len;
                    }
                    return;

                }
                else if (_readState == ReadState.readBody)
                {
                    int len = length - offset;

                    if (len >= _msgLength + _headLength - _bytesOffset)//body完整
                    {
                        int realLength = _msgLength + _headLength - _bytesOffset;
                        WriteBytes(bytes, offset, _recvBytes, _bytesOffset, realLength);//全部写入
                        offset += _msgLength + _headLength - _bytesOffset;

                        _receiver.Receive(_recvBytes, _headLength, _msgLength);//开始解析


                        Reset();
                        if (offset < length)//后面接了下一条消息
                        {
                            continue;
                        }
                    }
                    else
                    {
                        //能走到这里说明body不完整 先把byte记下 等下一条
                        WriteBytes(bytes, offset, _recvBytes, _bytesOffset, len);
                        _bytesOffset += len;
                        _readState = ReadState.readBody;
                    }
                    return;
                }

            }
        }

        private int GetMsgLen(int offset, byte[] bytes)
        {
            return (bytes[offset - 2] << 8) + bytes[offset - 1];
        }
        private int GetHeadLen(byte _byte)
        {
            int type = _byte >> 6;
            int len = 0;
            switch ((MsgType)type)
            {
                case MsgType.PUSH:
                    len = NetDefine.HEAD_LENGTH_PUSH;
                    break;
                case MsgType.RESPONSE:
                    len = NetDefine.HEAD_LENGTH_REQUEST;
                    break;
                case MsgType.HEART_BEAT:
                    len = NetDefine.HEAD_LENGTH_HEART;
                    break;
                case MsgType.REQUEST:
                    Log.Error($"[Net] MsgType搞错啦！！不是Request! 请确认服务器的地址和端口是否正确！");
                    break;
                default:
                    Log.Error($"[Net] MsgType未知的一条消息 type:{type}  请确认服务器的地址和端口是否正确！");
                    break;

            }
            return len;
        }
        private void WriteBytes(byte[] source, int sourceOffset, byte[] target, int targetOffset, int length)
        {
            Array.Copy(source, sourceOffset, target, targetOffset, length);
        }
        public void Reset()
        {
            _bytesOffset = 0;
            _headLength = 0;
            _msgLength = 0;
            if (_readState != ReadState.closed)
                _readState = ReadState.readHead;
        }
    }
}