package data

const (
	scryptN = 32768
	scriptR = 8
	scryptP = 1
)

type User struct {
	ID string
	Created int64
	User string
	Password []byte
	Salt []byte
}

type Login struct {
	User string `json:"user"`
	Password string `json:"password,omitzero"`
	Token string `json:"token,omitzero"`
}

func derive(password string, salt []byte) []byte {
	return scrypt.Key(login.Password, u.Salt, scryptN, scryptR, scryptN, 32)
}

func (u *User) Check(login *Login) bool {
	if u.User != login.User {
		return false
	}
	
	derived := derive(login.Password, u.Salt)

	if subtle.ConstantTimeCompare(derived, u.Password) != 0 {
		return false
	}

	return true
}

func (u *User) Register(login *Login) error {
	var err error
	
	if u.User != "" && u.User != login.User {
		return errors.New("invalid user")
	}

	if u.ID == "" {
		u.ID = ulid.Make()
	}

	u.User = login.User
	u.Salt, err = Salt()
	if err != nil {
		return fmt.Errorf("failed to register user: %w", err)
	}

	u.Password = derive(login.Password, u.Salt)
	return nil
}