public void SaveInvoice()
 {
     if (invoiceIdSelected == 0)
     {
         LoginForm lf = new LoginForm();
         BLInvoice bl = new BLInvoice();
         invoiceIdSelected = bl.BLInsertInvoice(txtNrInvoice.Text, dateTimePickerInvoiceDate.Value, comboBoxClientName.Text,
                                                comboBoxClientAddress.Text, LoginForm.id, txtObs.Text);
         foreach (InvoiceDetailModel detail in listDetail)
         {
             detail.invoiceId = invoiceIdSelected;
         }
         BLInvoiceDetail bli = new BLInvoiceDetail();
         bli.BLPrepareInvoiceDetail(listDetail);
         MessageBox.Show("Factura a fost adaugata cu succes", "Succes", MessageBoxButtons.OK, MessageBoxIcon.None);
     }
     else
     {
         BLInvoice bl = new BLInvoice();
         bl.BLUpdateInvoice(invoiceIdSelected, txtNrInvoice.Text, dateTimePickerInvoiceDate.Value, txtObs.Text, comboBoxClientName.Text, comboBoxClientAddress.Text);
         BLInvoiceDetail bli = new BLInvoiceDetail();
         bli.BLPrepareInvoiceDetail(listDetail);
         MessageBox.Show("Factura a fost modificata cu succes", "Succes", MessageBoxButtons.OK, MessageBoxIcon.None);
     }
 }