private void ButtonSignUP_Click(object sender, RoutedEventArgs e)
        {
            using (var writer = new StreamWriter("emails/emails", true))
                writer.WriteLine(registerMViewModel.RegisterModel.Email);
            User user = new User(registerMViewModel.RegisterModel.Login, registerMViewModel.RegisterModel.Email, registerMViewModel.RegisterModel.ConfirmPasswd);

            user.Serialize();
            RentalServiceMenu rentalSerivce = new RentalServiceMenu(user);

            LOGIN.Visibility  = Visibility.Visible;
            SignUP.Visibility = Visibility.Hidden;
            this.Hide();
            if (rentalSerivce.ShowDialog() == true)
            {
                this.Show();
            }
            else
            {
                this.Close();
            }
        }
        private void ButtonLogin_Click(object sender, RoutedEventArgs e)
        {
            bool is_admin_try = false;

            if (chb_alogin.IsChecked == true)
            {
                is_admin_try = true;
                if (File.Exists(admins_path + logTxtBox_login.Text))
                {
                    Admin admin = new Admin();
                    admin.Deserialize(admins_path + logTxtBox_login.Text);
                    if (admin.Passwd == passwdbox.Password)
                    {
                        chb_alogin.IsChecked = false;
                        AdminMenu rentalSerivce = new AdminMenu(admin);
                        this.Hide();
                        if (rentalSerivce.ShowDialog() == true)
                        {
                            this.Show();
                        }
                        else
                        {
                            this.Close();
                        }
                    }
                    else
                    {
                        MsgBox msgBox = new MsgBox("Authorization error", "Wrong password!");
                        msgBox.Owner = this;
                        msgBox.ShowDialog();
                    }
                }
                else
                {
                    chb_alogin.IsChecked = false;
                    MsgBox msgBox = new MsgBox("Authorization error", "No user with this login was found!");
                    msgBox.Owner = this;
                    msgBox.ShowDialog();
                }
            }
            if (!is_admin_try)
            {
                if (!File.Exists(users_path + logTxtBox_login.Text))
                {
                    MsgBox msgBox = new MsgBox("Authorization error", "No user with this login was found!");
                    msgBox.Owner = this;
                    msgBox.ShowDialog();
                }
                else
                {
                    User user = new User();
                    user.Deserialize(users_path + logTxtBox_login.Text);
                    if (user.Passwd == passwdbox.Password)
                    {
                        RentalServiceMenu rentalSerivce = new RentalServiceMenu(user);
                        this.Hide();
                        if (rentalSerivce.ShowDialog() == true)
                        {
                            this.Show();
                        }
                        else
                        {
                            this.Close();
                        }
                    }
                    else
                    {
                        MsgBox msgBox = new MsgBox("Authorization error", "Wrong password!");
                        msgBox.Owner = this;
                        msgBox.ShowDialog();
                    }
                }
            }
        }