package protocol

var _ Packet = (*TCPPacket)(nil)

type (
	TCPHeader struct {
		TransactionIdentifier uint16
		ProtocolIdentifier    uint16
		Length                uint16
		ModbusHeader
	}
	// TCPPacket modbus-tcp 数据帧，相对于rtu添加了协议头，减少了crc
	TCPPacket struct {
		*TCPHeader
		Data []byte
	}
)

func NewTCPPacket() *TCPPacket {
	return &TCPPacket{
		TCPHeader: &TCPHeader{
			TransactionIdentifier: 0,
			ProtocolIdentifier:    0,
			Length:                0,
			ModbusHeader:          ModbusHeader{},
		},
	}
}

func (p *TCPPacket) Copy() Packet {
	c := *p
	return &c
}

func (p *TCPPacket) GetHeader() interface{} {
	return p.TCPHeader
}

func (p *TCPPacket) GetLen() uint64 {
	return uint64(p.Length)
}

func (p *TCPPacket) GetBody() []byte {
	return p.Data
}

func (p *TCPPacket) GetAddress() uint8 {
	return p.Address
}

func (p *TCPPacket) GetFunction() uint8 {
	return p.Function
}

func (p *TCPPacket) SetBody(data []byte) {
	p.Data = data
	p.calcLength()
}

func (p *TCPPacket) SetError(err *MError) {
	p.Function = p.Function | 0x80
	p.Data = []byte{byte(*err)}
	p.calcLength()
}

func (p *TCPPacket) calcLength() {
	p.Length = uint16(len(p.Data) + 2)
}