package testclient

import (
	"encoding/binary"
	"errors"
	"ripple/crypto"
	"ripple/tests/internal/testclient/udpr"
)

var errInvalidUserRequest = errors.New("invalid user request")
var errInvalidSignature   = errors.New("invalid signature")
var errCounterMismatch    = errors.New("not a response to the sent counter")

const userType = 0x01

type clientTransport struct {
	c *udpr.UDPRClient
	secretKey [32]byte
}

func newClientTransport(c *udpr.UDPRClient, secretKey [32]byte) *clientTransport {
	return &clientTransport{c: c, secretKey: secretKey}
}

func (t *clientTransport) receive(counterSent uint32) (byte, []byte, error) {
	payload, err := t.c.Read()
	if err != nil {
		return 0, nil, err
	}
	if len(payload) < 5+32 {
		return 0, nil, errInvalidUserRequest
	}
	if !crypto.VerifySignature(payload, t.secretKey) {
		return 0, nil, errInvalidSignature
	}
	counter := binary.BigEndian.Uint32(payload[0:4])
	if counter != counterSent {
		return 0, nil, errCounterMismatch
	}
	status := payload[4]
	data := payload[5 : len(payload)-32]
	return status, data, nil
}

func (t *clientTransport) send(req UserRequest) {
	buf := make([]byte, 5)
	buf[0] = userType
	binary.BigEndian.PutUint32(buf[1:5], req.Counter)
	buf = append(buf, req.Instruction.Command)
	buf = append(buf, req.Instruction.Arguments...)
	signed := crypto.SignData(buf, t.secretKey)
    go func() {
        if err := t.c.Write(signed); err != nil {
            panic(err)
        }
    }()
}