package datastructures

import (
	"bytes"
	"errors"
	"fmt"
)

type SignerResponse struct {
	Version   uint8
	Action    Action
	Reserved1 uint8
	Reserved2 uint8
	Content1  string
	Content2  string
	Content3  string
}

func SignerResponseFromData(lengthBytes []byte, blockData []byte, checkSum byte) (*SignerResponse, error) {
	headerLength := decode24BitLength(lengthBytes)
	headerBytes := blockData[3 : 3+headerLength]

	contentBytes := blockData[3+headerLength:]
	content1Length := decode24BitLength(contentBytes[0:3])
	content1 := string(contentBytes[3 : 3+content1Length])

	content2Offset := 3 + content1Length
	content2Length := decode24BitLength(contentBytes[content2Offset : content2Offset+3])
	content2 := string(contentBytes[3+content2Offset : 3+content2Offset+content2Length])

	content3Offset := 3 + content2Offset + content2Length
	content3Length := decode24BitLength(contentBytes[content3Offset : content3Offset+3])
	content3 := string(contentBytes[3+content3Offset : 3+content3Offset+content3Length])

	calculated := CalculateXorCheckSum([][]byte{lengthBytes, blockData})
	if checkSum != calculated {
		return nil, errors.New(fmt.Sprintf("invalid checksum expected 0x%x got 0x%x", calculated, checkSum))
	}

	return &SignerResponse{
		Version:   headerBytes[0],
		Action:    Action(headerBytes[1]),
		Reserved1: headerBytes[2],
		Reserved2: headerBytes[3],
		Content1:  content1,
		Content2:  content2,
		Content3:  content3,
	}, nil
}

func (r SignerResponse) Serialize() []byte {
	headerBytes := []byte{r.Version, byte(r.Action), r.Reserved1, r.Reserved2}
	content1Bytes := []byte(r.Content1)
	content2Bytes := []byte(r.Content2)
	content3Bytes := []byte(r.Content3)
	blockBytes := bytes.Join([][]byte{
		encode24BitLength(headerBytes), headerBytes,
		encode24BitLength(content1Bytes), content1Bytes,
		encode24BitLength(content2Bytes), content2Bytes,
		encode24BitLength(content3Bytes), content3Bytes,
	}, []byte{})
	return bytes.Join([][]byte{encode24BitLength(blockBytes), blockBytes}, []byte{})
}