public static void Save_Invoice(InvoiceForm f)
 {
     //save Invoice
     try
     {
         if (f.bunifuDatepicker1.Value != null && (f.Textbox1ID.Text != "" || f.Textbox1ID.Text != null))
         {
             //save Invoiec
             int      InvID       = int.Parse(f.Textbox1ID.Text);
             DateTime InvDate     = f.bunifuDatepicker1.Value;
             int      InvSupplier = int.Parse(f.comboBox1.SelectedValue.ToString());
             Invoice  inv         = new Invoice(InvID, InvDate, InvSupplier);
             inv.AddInvoice(dt);
             //save InvoiceDetails
             InvoiceDetails invDetails;
             foreach (DataGridViewRow r in f.dataGridView11.Rows)
             {
                 string MedecineID = r.Cells["ProductID"].Value.ToString();
                 string VAT        = r.Cells["VAT"].Value.ToString();
                 string Price      = r.Cells["Price"].Value.ToString();
                 string Discount   = r.Cells["Discount"].Value.ToString();
                 string quantity   = r.Cells["Quantity"].Value.ToString();
                 string expiryDate = r.Cells["Date"].Value.ToString();
                 invDetails = new InvoiceDetails(MedecineID, InvID, quantity, Price, VAT.Replace("%", ""), expiryDate, Discount.Replace("%", ""));
                 invDetails.AddInvoiceDetails(dt);
                 Stocks.UpdateStocks(dt, int.Parse(MedecineID), int.Parse(quantity));
             }
         }
         else
         {
             MessageBox.Show("Please Fill ID and Date ");
         }
     }
     catch
     {
         //ADD DELETE FUNCTION
         MessageBox.Show("ERROR!!");
     }
 }