private void doneButton_Click(object sender, RoutedEventArgs e)
        {
            var PaymentWindowScreen = new PaymentWindow(0, id2TextBlock.Text, customernameTextBox.Text, phonenumberTextBox.Text, addressTextBox.Text,
                                                        staffnameTextBlock.Text, _goodsList.ToList(), totalTextBlock.Text);

            if (PaymentWindowScreen.ShowDialog() == true)
            {
                for (int i = 0; i < _goodsList.Count; i++)
                {
                    Bill newBill = new Bill()
                    {
                        BillCode            = id2TextBlock.Text,
                        CustomerName        = customernameTextBox.Text,
                        CustomerPhoneNumber = phonenumberTextBox.Text,
                        CustomerAddress     = addressTextBox.Text,
                        ID_Staff            = _userID,
                        ID_Goods            = _goodsList[i].ID,
                        DateTime            = DateTime.Now.Date,
                        Total = double.Parse(totalTextBlock.Text),
                        VAT   = 10,
                    };

                    //Decrease number of this goods
                    _goodsList[i].Number--;
                    busGoods.UpdateGoods(_goodsList[i]);


                    busBill.AddBill(newBill);
                }

                //Giống sự kiện cancelbillButton_Click
                id2TextBlock.Text        = busBill.GetNextBillCode();
                customernameTextBox.Text = "";
                phonenumberTextBox.Text  = "";
                addressTextBox.Text      = "";
                totalTextBlock.Text      = "0";
                cashTextBox.Text         = "0";
                _goodsList.Clear();

                return;
            }
            else
            {
                return;
            }
        }
        private void searchButton_Click(object sender, RoutedEventArgs e)
        {
            if (searchTextBox.Text == "")
            {
                return;
            }

            List <Bill> bills = billListView.ItemsSource as List <Bill>;

            for (int i = 0; i < bills.Count; i++)
            {
                if (bills[i].BillCode == searchTextBox.Text)
                {
                    List <Good> goodsOfSelectedBill = new List <Good>();

                    for (int j = 0; j < busBill.GetID_GoodsByBillCode(bills[i].BillCode).Count; j++)
                    {
                        goodsOfSelectedBill.Add(busGoods.GetGoodsById(busBill.GetID_GoodsByBillCode(bills[i].BillCode)[j]));
                    }

                    var PaymentWindowScreen = new PaymentWindow(1, bills[i].BillCode, bills[i].CustomerName, bills[i].CustomerPhoneNumber, bills[i].CustomerAddress,
                                                                userConverter.Convert(bills[i].ID_Staff.Value, null, null, null) as string, goodsOfSelectedBill, bills[i].Total.ToString());

                    if (PaymentWindowScreen.ShowDialog() == true)
                    {
                        return;
                    }
                    else
                    {
                        return;
                    }
                }
            }

            var AnnouncementWindowScreen = new AnnouncementWindow("DON'T FIND THIS CODE... PLEASE TYPE AGAIN!");

            if (AnnouncementWindowScreen.ShowDialog() == true)
            {
                return;
            }
            else
            {
                return;
            }
        }
        private void billListView_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            var selectedBill = billListView.SelectedItem as Bill;

            List <Good> goodsOfSelectedBill = new List <Good>();

            for (int i = 0; i < busBill.GetID_GoodsByBillCode(selectedBill.BillCode).Count; i++)
            {
                goodsOfSelectedBill.Add(busGoods.GetGoodsById(busBill.GetID_GoodsByBillCode(selectedBill.BillCode)[i]));
            }

            var PaymentWindowScreen = new PaymentWindow(1, selectedBill.BillCode, selectedBill.CustomerName, selectedBill.CustomerPhoneNumber, selectedBill.CustomerAddress,
                                                        userConverter.Convert(selectedBill.ID_Staff.Value, null, null, null) as string, goodsOfSelectedBill, selectedBill.Total.ToString());

            if (PaymentWindowScreen.ShowDialog() == true)
            {
                return;
            }
            else
            {
                return;
            }
        }