public Invoice AddInvoice(Invoice invoice)
{
//var nextId = invoices.Count == 0 ? 1 : invoices.Max(i => i.Id);
//var persistedInvoice = new Invoice(nextId) {
// Ammount = invoice.Ammount,
// DueDate = invoice.DueDate,
// InvoiceNumber = invoice.InvoiceNumber,
// InvoiceDate = invoice.InvoiceDate,
// Quantity = invoice.Quantity,
// Status = invoice.Status
//};
//invoices.Add(persistedInvoice);
var savedInvoice = ledgerRepository.AddInvoice(invoice);
return(savedInvoice);
}