private void btnInvoice_Click(object sender, EventArgs e)
{
if(lvItems.Items.Count <= 0)
return;
if (_order.Customer == null)
SelectCustomer();
if (_order.Customer == null)
return;
var items = lvItems.Items.OfType<ListViewItem>()
.Select(lvi => lvi.Tag as OrderItem)
.ToList();
var invoice = InvoiceBuilder.Create(FinancialHandler.GenerateInvoiceNumber(),
CreateInvoice(items),
_order.Customer);
invoice.Total = items.Select(oi => oi.CalculateTotal())
.DefaultIfEmpty(0)
.Sum();
var desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
var path = Path.Combine(desktopPath, $"Factura-{invoice.Number}.pdf");
var pdfWriter = new PdfWriter(path);
pdfWriter.Write(invoice.ToString());
pdfWriter.Save();
Process.Start(path);
}