package main

import (
	"encoding/binary"
	"io"
)

const (
	RemoteGetState      = uint16(0x01)
	RemoteHandleMessage = uint16(0x02)
	ResponseBody        = uint16(0x03)
)

type CartPacket struct {
	Version     uint16
	MessageType uint16
	Id          CartId
	DataLength  uint16
}

type ResponsePacket struct {
	Version     uint16
	MessageType uint16
	DataLength  uint16
}

func SendCartPacket(conn io.Writer, id CartId, messageType uint16, datafn func(w io.Writer) error) error {
	data, err := GetData(datafn)
	if err != nil {
		return err
	}
	binary.Write(conn, binary.LittleEndian, CartPacket{
		Version:     2,
		MessageType: messageType,
		Id:          id,
		DataLength:  uint16(len(data)),
	})
	_, err = conn.Write(data)
	return err
}

func SendPacket(conn io.Writer, messageType uint16, datafn func(w io.Writer) error) error {
	data, err := GetData(datafn)
	if err != nil {
		return err
	}
	binary.Write(conn, binary.LittleEndian, ResponsePacket{
		Version:     1,
		MessageType: messageType,
		DataLength:  uint16(len(data)),
	})
	_, err = conn.Write(data)
	return err
}

// func ReceiveCartPacket(conn io.Reader) (CartPacket, []byte, error) {
// 	var packet CartPacket
// 	err := binary.Read(conn, binary.LittleEndian, &packet)
// 	if err != nil {
// 		return packet, nil, err
// 	}
// 	data := make([]byte, packet.DataLength)
// 	_, err = conn.Read(data)
// 	return packet, data, err
// }

func ReceivePacket(conn io.Reader) (uint16, []byte, error) {
	var packet ResponsePacket
	err := binary.Read(conn, binary.LittleEndian, &packet)
	if err != nil {
		return packet.MessageType, nil, err
	}
	data := make([]byte, packet.DataLength)
	_, err = conn.Read(data)
	return packet.MessageType, data, err
}