Fix for bug #922 & bug #949 (#951)

* Fix "Do not propose lightning payment if value of the invoice is above..."

* Fix "Do not propose lightning payment if value of the invoice is above..." take care of the GAP edge case where OnChainMinValue > LightningMaxValue

* Fix "Do not propose on chain payment if the value of the invoice is below..." and take care of the GAP edge case

* Add test to cover all case and fix small issue

* Simplified version, with less validation

BTCPayServer.Tests/PaymentHandlerTest.cs

@@ -0,0 +1,239 @@
+using BTCPayServer.Tests.Logging;
+using NBitcoin;
+using Xunit;
+using Xunit.Abstractions;
+using BTCPayServer.Data;
+using BTCPayServer.Services.Rates;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using BTCPayServer.Payments;
+using BTCPayServer.Payments.Bitcoin;
+using BTCPayServer.Payments.Lightning;
+using BTCPayServer.Rating;
+
+namespace BTCPayServer.Tests
+{
+    public class PaymentHandlerTest
+    {
+        private BitcoinLikePaymentHandler handlerBTC;
+        private LightningLikePaymentHandler handlerLN;
+        private Dictionary<CurrencyPair, Task<RateResult>> currencyPairRateResult;
+        
+        public PaymentHandlerTest(ITestOutputHelper helper)
+        {
+ 
+#pragma warning disable CS0618            
+            
+            Logs.Tester = new XUnitLog(helper) { Name = "Tests" };
+            Logs.LogProvider = new XUnitLogProvider(helper);
+            
+            var dummy = new Key().PubKey.GetAddress(ScriptPubKeyType.Legacy, Network.RegTest).ToString();
+            var networkProvider = new BTCPayNetworkProvider(NetworkType.Regtest);
+
+            currencyPairRateResult = new Dictionary<CurrencyPair, Task<RateResult>>();
+            
+            var rateResultUSDBTC = new RateResult();
+            rateResultUSDBTC.BidAsk= new BidAsk(1m);
+
+            var rateResultBTCUSD = new RateResult();
+            rateResultBTCUSD.BidAsk= new BidAsk(1m);
+            
+            currencyPairRateResult.Add(new CurrencyPair("USD", "BTC"), Task.FromResult(rateResultUSDBTC));
+            currencyPairRateResult.Add(new CurrencyPair("BTC", "USD"), Task.FromResult(rateResultBTCUSD));
+ 
+            handlerBTC = new BitcoinLikePaymentHandler(null, networkProvider, null, null);
+            handlerLN = new LightningLikePaymentHandler(null, null, networkProvider, null);
+            
+#pragma warning restore CS0618               
+        }
+
+        [Fact]
+        public void CanPayWithLightningWhenInvoiceTotalUnderLightningMaxValue()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = null,
+                LightningMaxValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"}
+            };
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.LightningLike);
+            
+            //When
+            var totalInvoiceAmount = new Money(98m, MoneyUnit.BTC);
+            
+           
+            //Then
+            var errorMessage = handlerLN.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.Equal(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }
+
+    
+        [Fact]
+        public void CannotPayWithLightningWhenInvoiceTotalAboveLightningMaxValue()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = null,
+                LightningMaxValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"}
+            };
+            var totalInvoiceAmount = new Money(102m, MoneyUnit.BTC);
+            
+            //When
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.LightningLike);
+           
+            //Then
+            var errorMessage = handlerLN.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.NotEqual(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }    
+        
+        [Fact]
+        public void CanPayWithLightningWhenInvoiceTotalEqualLightningMaxValue()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = null,
+                LightningMaxValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"}
+            };
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.LightningLike);
+            
+            //When
+            var totalInvoiceAmount = new Money(100m, MoneyUnit.BTC);
+           
+            //Then
+            var errorMessage = handlerLN.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.Equal(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }
+
+        [Fact]
+        public void CanPayWithBitcoinWhenInvoiceTotalAboveOnChainMinValue()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"},
+                LightningMaxValue = null
+            };
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.BTCLike);
+            
+            //When
+            var totalInvoiceAmount = new Money(105m, MoneyUnit.BTC);
+            
+           
+            //Then
+            var errorMessage = handlerBTC.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.Equal(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }
+
+    
+        [Fact]
+        public void CannotPayWithBitcoinWhenInvoiceTotalUnderOnChainMinValue()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"},
+                LightningMaxValue = null
+            };
+            var totalInvoiceAmount = new Money(98m, MoneyUnit.BTC);
+            
+            //When
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.BTCLike);
+           
+            //Then
+            var errorMessage = handlerBTC.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.NotEqual(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }    
+        
+        [Fact]
+        public void CanPayWithBitcoinWhenInvoiceTotalEqualOnChainMinValue()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"},
+                LightningMaxValue = null
+            };
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.BTCLike);
+            
+            //When
+            var totalInvoiceAmount = new Money(100m, MoneyUnit.BTC);
+           
+            //Then
+            var errorMessage = handlerBTC.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.Equal(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }
+   
+        
+        [Fact]
+        public void CannotPayWithBitcoinWhenInvoiceTotalUnderOnChainMinValueWhenLightningMaxValueIsGreater()
+        {
+            
+#pragma warning disable CS0618
+            
+            //Given
+            var store = new StoreBlob
+            {
+                OnChainMinValue = new CurrencyValue() {Value = 50.00m, Currency = "USD"},
+                LightningMaxValue = new CurrencyValue() {Value = 100.00m, Currency = "USD"}
+            };
+            var paymentMethodId = new PaymentMethodId("BTC", PaymentTypes.BTCLike);
+            
+            //When
+            var totalInvoiceAmount = new Money(45m, MoneyUnit.BTC);
+           
+            //Then
+            var errorMessage = handlerBTC.IsPaymentMethodAllowedBasedOnInvoiceAmount(store, currencyPairRateResult,
+                totalInvoiceAmount, paymentMethodId);
+            
+            Assert.NotEqual(errorMessage.Result, string.Empty);
+
+#pragma warning restore CS0618     
+        }  
+        
+        
+    }
+}

BTCPayServer/Payments/Bitcoin/BitcoinLikePaymentHandler.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Globalization;
 using System.Linq;
 using System.Threading.Tasks;
 using BTCPayServer.Data;
@@ -11,9 +10,6 @@ using BTCPayServer.Services;
 using BTCPayServer.Services.Invoices;
 using BTCPayServer.Services.Rates;
 using NBitcoin;
-using NBitpayClient;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
 
 namespace BTCPayServer.Payments.Bitcoin
 {
@@ -73,37 +69,35 @@ namespace BTCPayServer.Payments.Bitcoin
         public override async Task<string> IsPaymentMethodAllowedBasedOnInvoiceAmount(StoreBlob storeBlob,
             Dictionary<CurrencyPair, Task<RateResult>> rate, Money amount, PaymentMethodId paymentMethodId)
         {
+            
             Func<Money, Money, bool> compare = null;
             CurrencyValue limitValue = null;
             string errorMessage = null;
-            if (paymentMethodId.PaymentType == PaymentTypes.LightningLike &&
-               storeBlob.LightningMaxValue != null)
+            
+            if (storeBlob.OnChainMinValue != null)
             {
-                compare = (a, b) => a > b;
-                limitValue = storeBlob.LightningMaxValue;
-                errorMessage = "The amount of the invoice is too high to be paid with lightning";
-            }
-            else if (paymentMethodId.PaymentType == PaymentTypes.BTCLike &&
-               storeBlob.OnChainMinValue != null)
-            {
-                compare = (a, b) => a < b;
+                compare = (value, limit) => value < limit;
                 limitValue = storeBlob.OnChainMinValue;
                 errorMessage = "The amount of the invoice is too low to be paid on chain";
             }
 
+            
             if (compare != null)
             {
-                var limitValueRate = await rate[new CurrencyPair(paymentMethodId.CryptoCode, storeBlob.OnChainMinValue.Currency)];
-                if (limitValueRate.BidAsk != null)
+                var currentRateToCrypto = await rate[new CurrencyPair(paymentMethodId.CryptoCode, limitValue.Currency)];
+                
+                if (currentRateToCrypto.BidAsk != null)
                 {
-                    var limitValueCrypto = Money.Coins(limitValue.Value / limitValueRate.BidAsk.Bid);
+                    var limitValueCrypto = Money.Coins(limitValue.Value / currentRateToCrypto.BidAsk.Bid);
                     if (compare(amount, limitValueCrypto))
                     {
                         return errorMessage;
                     }
                 }
             }
+            
             return string.Empty;
+
         }
 
         public override IEnumerable<PaymentMethodId> GetSupportedPaymentMethods()

BTCPayServer/Payments/IPaymentMethodHandler.cs

@@ -7,8 +7,6 @@ using BTCPayServer.Rating;
 using BTCPayServer.Services.Invoices;
 using BTCPayServer.Services.Rates;
 using NBitcoin;
-using NBitpayClient;
-using Newtonsoft.Json.Linq;
 using InvoiceResponse = BTCPayServer.Models.InvoiceResponse;
 
 namespace BTCPayServer.Payments

BTCPayServer/Payments/Lightning/LightningLikePaymentHandler.cs

@@ -13,9 +13,6 @@ using BTCPayServer.Services.Invoices;
 using BTCPayServer.Services;
 using BTCPayServer.Services.Rates;
 using NBitcoin;
-using NBitpayClient;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
 
 namespace BTCPayServer.Payments.Lightning
 {
@@ -149,23 +146,34 @@ namespace BTCPayServer.Payments.Lightning
         public override async Task<string> IsPaymentMethodAllowedBasedOnInvoiceAmount(StoreBlob storeBlob,
             Dictionary<CurrencyPair, Task<RateResult>> rate, Money amount, PaymentMethodId paymentMethodId)
         {
-            if (storeBlob.OnChainMinValue == null)
+
+            Func<Money, Money, bool> compare = null;
+            CurrencyValue limitValue = null;
+            string errorMessage = null;
+            
+            if (storeBlob.LightningMaxValue != null)
             {
-                return null;
+                compare = (value, limit) => value > limit;
+                limitValue = storeBlob.LightningMaxValue;
+                errorMessage = "The amount of the invoice is too high to be paid with lightning";
             }
 
-            var limitValueRate = await rate[new CurrencyPair(paymentMethodId.CryptoCode, storeBlob.OnChainMinValue.Currency)];
             
-            if (limitValueRate.BidAsk != null)
+            if (compare != null)
             {
-                var limitValueCrypto = Money.Coins(storeBlob.OnChainMinValue.Value / limitValueRate.BidAsk.Bid);
-
-                if (amount < limitValueCrypto)
+                var currentRateToCrypto = await rate[new CurrencyPair(paymentMethodId.CryptoCode, limitValue.Currency)];
+                
+                if (currentRateToCrypto.BidAsk != null)
                 {
-                    return null;
+                    var limitValueCrypto = Money.Coins(limitValue.Value / currentRateToCrypto.BidAsk.Bid);
+                    if (compare(amount, limitValueCrypto))
+                    {
+                        return errorMessage;
+                    }
                 }
             }
-            return "The amount of the invoice is too high to be paid with lightning";
+            
+            return string.Empty;
         }
 
         public override void PreparePaymentModel(PaymentModel model, InvoiceResponse invoiceResponse)