package msg

import (
	"bytes"
	"encoding/binary"
)

const (
	ProtocolType_Sync   = 0x01
	ProtocolType_NoSync = 0x02
)

const (
	MessageType_A   = 0x80
	MessageType_B   = 0x81
	MessageType_SSE = 0x90
	MessageType_SSR = 0x91
)

const (
	CRC_POLY_1 = 0x100D4E63 //通道1的CRC多项式
	CRC_POLY_2 = 0x8CE56011 //通道2的CRC多项式
)

const (
	SCW_1 = 0xAE390B5A //通道1的SCW
	SCW_2 = 0xC103589C //通道2的SCW
)

const (
	T_POLY_1 = 0x0FC22F87 //通道1的时间戳生成多项式
	T_POLY_2 = 0xC3E887E1 //通道2的时间戳生成多项式
)

const Twait_sse = 3 //默认sse等待回应的周期数

func GetMessageType(data []byte) byte {
	return data[1]
}

type MsgHeader struct {
	ProtocolType byte   //协议交互类别
	MessageType  byte   //报文类型
	SourceAddr   uint16 //源地址
	TargetAddr   uint16 //目的地址
}

func (m *MsgHeader) encode() []byte {
	var data []byte
	data = append(data, m.ProtocolType)
	data = append(data, m.MessageType)
	data = binary.LittleEndian.AppendUint16(data, m.SourceAddr)
	data = binary.LittleEndian.AppendUint16(data, m.TargetAddr)
	return data
}

func (m *MsgHeader) decode(data []byte) error {
	buf := bytes.NewBuffer(data)
	err := binary.Read(buf, binary.LittleEndian, m)
	return err
}