package certifer

import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"math/big"
	"math/rand"
	"time"
)

const maxCreateKeyRounds = 3

var ecdsacurve = elliptic.P256()

// KeyParameters hold the ecdsa curve parameters of private (and public, despite these are redundand values) keys.
type KeyParameters struct {
	D, X, Y *big.Int
}

// NewKeyParameters extracts key information from a given ecdsa private key and returns a KeyParameters instance.
func NewKeyParameters(key *ecdsa.PrivateKey) *KeyParameters {
	return &KeyParameters{
		D: key.D,
		X: key.X,
		Y: key.Y,
	}
}

// Key creates a new ecdsa.PrivateKey from the given KeyParameters
func (k *KeyParameters) Key() *ecdsa.PrivateKey {
	priv := new(ecdsa.PrivateKey)
	priv.PublicKey.Curve = ecdsacurve
	priv.D = k.D
	priv.PublicKey.X, priv.PublicKey.Y = k.X, k.Y
	return priv
}

func createKeyPair() *ecdsa.PrivateKey {
	// generate key pair
	var pk *ecdsa.PrivateKey
	var err error
	for i := 0; i < 3; i++ {
		r := getRandom()
		pk, err = ecdsa.GenerateKey(ecdsacurve, r)
		if err != nil {
			//log.WithError(err).Error("cannot create key pair")
			continue
		}
		return pk
	}
	panic(err)
}

var theRand *rand.Rand = nil

func getRandom() *rand.Rand {
	if theRand == nil {
		rnd := rand.NewSource(time.Now().Unix())
		theRand = rand.New(rnd)
	}
	return theRand
}