InvoiceDue field in export

BTCPayServer.Tests/UnitTest1.cs

@@ -1598,7 +1598,7 @@ donation:
 
                 var invoice = user.BitPay.CreateInvoice(new Invoice()
                 {
-                    Price = 500,
+                    Price = 10,
                     Currency = "USD",
                     PosData = "posData",
                     OrderId = "orderId",
@@ -1606,6 +1606,8 @@ donation:
                     FullNotifications = true
                 }, Facade.Merchant);
 
+                var networkFee = Money.Satoshis(10000);
+
                 // ensure 0 invoices exported because there are no payments yet
                 var jsonResult = user.GetController<InvoiceController>().Export("json").GetAwaiter().GetResult();
                 var result = Assert.IsType<ContentResult>(jsonResult);
@@ -1614,18 +1616,41 @@ donation:
 
                 var cashCow = tester.ExplorerNode;
                 var invoiceAddress = BitcoinAddress.Create(invoice.CryptoInfo[0].Address, cashCow.Network);
-                var firstPayment = invoice.CryptoInfo[0].TotalDue - Money.Satoshis(10);
+                // 
+                var firstPayment = invoice.CryptoInfo[0].TotalDue - 3*networkFee;
                 cashCow.SendToAddress(invoiceAddress, firstPayment);
+                Thread.Sleep(1000); // prevent race conditions, ordering payments
+                // look if you can reduce thread sleep, this was min value for me
+
+                // should reduce invoice due by 0 USD because payment = network fee
+                cashCow.SendToAddress(invoiceAddress, networkFee);
+                Thread.Sleep(1000);
+
+                // pay remaining amount
+                cashCow.SendToAddress(invoiceAddress, 4*networkFee);
+                Thread.Sleep(1000);
 
                 Eventually(() =>
                 {
                     var jsonResultPaid = user.GetController<InvoiceController>().Export("json").GetAwaiter().GetResult();
                     var paidresult = Assert.IsType<ContentResult>(jsonResultPaid);
                     Assert.Equal("application/json", paidresult.ContentType);
-                    Assert.Contains("\"InvoiceItemDesc\": \"Some \\\", description\"", paidresult.Content);
-                    Assert.Contains("\"InvoicePrice\": 500.0", paidresult.Content);
-                    Assert.Contains("\"ConversionRate\": 5000.0", paidresult.Content);
-                    Assert.Contains($"\"InvoiceId\": \"{invoice.Id}\",", paidresult.Content);
+
+                    var parsedJson = JsonConvert.DeserializeObject<object[]>(paidresult.Content);
+                    Assert.Equal(3, parsedJson.Length);
+
+                    var pay1str = parsedJson[0].ToString();
+                    Assert.Contains("\"InvoiceItemDesc\": \"Some \\\", description\"", pay1str);
+                    Assert.Contains("\"InvoiceDue\": 1.5", pay1str);
+                    Assert.Contains("\"InvoicePrice\": 10.0", pay1str);
+                    Assert.Contains("\"ConversionRate\": 5000.0", pay1str);
+                    Assert.Contains($"\"InvoiceId\": \"{invoice.Id}\",", pay1str);
+
+                    var pay2str = parsedJson[1].ToString();
+                    Assert.Contains("\"InvoiceDue\": 1.5", pay2str);
+
+                    var pay3str = parsedJson[2].ToString();
+                    Assert.Contains("\"InvoiceDue\": 0", pay3str);
                 });
 
                 /*

BTCPayServer/Services/Invoices/Export/InvoiceExport.cs

@@ -52,6 +52,8 @@ namespace BTCPayServer.Services.Invoices.Export
         private IEnumerable<ExportInvoiceHolder> convertFromDb(InvoiceEntity invoice)
         {
             var exportList = new List<ExportInvoiceHolder>();
+
+            var invoiceDue = invoice.ProductInformation.Price;
             // in this first version we are only exporting invoices that were paid
             foreach (var payment in invoice.GetPayments())
             {
@@ -64,6 +66,9 @@ namespace BTCPayServer.Services.Invoices.Export
 
                 var pmethod = invoice.GetPaymentMethod(payment.GetPaymentMethodId(), Networks);
 
+                var paidAfterNetworkFees = pdata.GetValue() - pmethod.TxFee.ToDecimal(NBitcoin.MoneyUnit.BTC);
+                invoiceDue -=  paidAfterNetworkFees * pmethod.Rate;
+
                 var target = new ExportInvoiceHolder
                 {
                     ReceivedDate = payment.ReceivedTime.UtcDateTime,
@@ -73,6 +78,12 @@ namespace BTCPayServer.Services.Invoices.Export
                     PaymentType = payment.GetPaymentMethodId().PaymentType == Payments.PaymentTypes.BTCLike ? "OnChain" : "OffChain",
                     Destination = payment.GetCryptoPaymentData().GetDestination(Networks.GetNetwork(cryptoCode)),
                     Paid = pdata.GetValue().ToString(CultureInfo.InvariantCulture),
+                    // Adding NetworkFee because Paid doesn't take into account network fees
+                    // so if fee is 10000 satoshis, customer can essentially send infinite number of tx
+                    // and merchant effectivelly would receive 0 BTC, invoice won't be paid
+                    // while looking just at export you could sum Paid and assume merchant "received payments"
+                    NetworkFee = pmethod.TxFee.ToDecimal(NBitcoin.MoneyUnit.BTC).ToString(CultureInfo.InvariantCulture),
+                    InvoiceDue = invoiceDue,
                     OrderId = invoice.OrderId,
                     StoreId = invoice.StoreId,
                     InvoiceId = invoice.Id,
@@ -112,12 +123,14 @@ namespace BTCPayServer.Services.Invoices.Export
         public string PaymentId { get; set; }
         public string Destination { get; set; }
         public string PaymentType { get; set; }
-        public string Paid { get; set; }
         public string CryptoCode { get; set; }
         public decimal ConversionRate { get; set; }
+        public string Paid { get; set; }
+        public string NetworkFee { get; set; }
 
-        public decimal InvoicePrice { get; set; }
         public string InvoiceCurrency { get; set; }
+        public decimal InvoiceDue { get; set; }
+        public decimal InvoicePrice { get; set; }
         public string InvoiceItemCode { get; set; }
         public string InvoiceItemDesc { get; set; }
         public string InvoiceFullStatus { get; set; }

BTCPayServer/Services/Invoices/InvoiceEntity.cs

@@ -681,7 +681,7 @@ namespace BTCPayServer.Services.Invoices
         /// </summary>
         public Money NetworkFee { get; set; }
         /// <summary>
-        /// Minimum required to be paid in order to accept invocie as paid
+        /// Minimum required to be paid in order to accept invoice as paid
         /// </summary>
         public Money MinimumTotalDue { get; set; }
     }