Recommended exchange to be resolved during Invoice Creation (#5976)

* Recommended Exchange Rate Selection during Invoice Creation

* Make Recommended exchanges pluginifiable

BTCPayServer.Rating/RateRules.cs

@@ -203,7 +203,7 @@ namespace BTCPayServer.Rating
             return (ExpressionSyntax)CSharpSyntaxTree.ParseText(str, new CSharpParseOptions(LanguageVersion.Default).WithKind(SourceCodeKind.Script)).GetRoot().ChildNodes().First().ChildNodes().First().ChildNodes().First();
         }
 
-        public static RateRules Combine(RateRules[] rateRules)
+        public static RateRules Combine(IEnumerable<RateRules> rateRules)
         {
             var str = string.Join(Environment.NewLine, rateRules.Select(r => r.ToString()));
             return Parse(str);

BTCPayServer.Tests/GreenfieldAPITests.cs

@@ -4284,7 +4284,7 @@ namespace BTCPayServer.Tests
             config = await clientBasic.GetStoreRateConfiguration(user.StoreId);
             Assert.Equal("X_X = coingecko(X_X);", config.EffectiveScript);
 
-            await AssertValidationError(new[] { "EffectiveScript", "PreferredSource" }, () =>
+            await AssertValidationError(new[] { "EffectiveScript" }, () =>
             clientBasic.UpdateStoreRateConfiguration(user.StoreId, new StoreRateConfiguration() { IsCustomScript = false, EffectiveScript = "BTC_XYZ = 1;" }));
 
             await AssertValidationError(new[] { "EffectiveScript" }, () =>

BTCPayServer.Tests/SeleniumTester.cs

@@ -196,7 +196,7 @@ retry:
             TestLogs.LogInformation($"Created store {name}");
             Driver.WaitForElement(By.Id("Name")).SendKeys(name);
             var rateSource = new SelectElement(Driver.FindElement(By.Id("PreferredExchange")));
-            Assert.Equal("Kraken (Recommended)", rateSource.SelectedOption.Text);
+            Assert.Equal("Recommendation (Kraken)", rateSource.SelectedOption.Text);
             rateSource.SelectByText("CoinGecko");
             Driver.WaitForElement(By.Id("Create")).Click();
             Driver.FindElement(By.Id("StoreNav-StoreSettings")).Click();

BTCPayServer.Tests/ThirdPartyTests.cs

@@ -9,6 +9,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using BTCPayServer.Controllers;
 using BTCPayServer.Data;
+using BTCPayServer.Hosting;
 using BTCPayServer.Models.StoreViewModels;
 using BTCPayServer.Models.WalletViewModels;
 using BTCPayServer.Rating;
@@ -357,12 +358,13 @@ retry:
             var factory = FastTests.CreateBTCPayRateFactory();
             var fetcher = new RateFetcher(factory);
             var provider = CreateDefaultRates(ChainName.Mainnet);
+            var defaultRules = new DefaultRulesCollection(provider.Select(p => p.DefaultRates));
             var b = new StoreBlob();
             string[] temporarilyBroken = Array.Empty<string>();
-            foreach (var k in StoreBlob.RecommendedExchanges)
+            foreach (var k in defaultRules.RecommendedExchanges)
             {
                 b.DefaultCurrency = k.Key;
-                var rules = b.GetDefaultRateRules(provider.Select(p => p.DefaultRates));
+                var rules = b.GetDefaultRateRules(defaultRules);
                 var pairs = new[] { CurrencyPair.Parse($"BTC_{k.Key}") }.ToHashSet();
                 var result = fetcher.FetchRates(pairs, rules, null, default);
                 foreach ((CurrencyPair key, Task<RateResult> value) in result)
@@ -389,11 +391,13 @@ retry:
         public async Task CanGetRateCryptoCurrenciesByDefault()
         {
             using var cts = new CancellationTokenSource(60_000);
-            var provider = CreateDefaultRates(ChainName.Mainnet);
+            var provider = CreateDefaultRates(ChainName.Mainnet, exchangeRecommendation: true);
+            var defaultRules = new DefaultRulesCollection(provider.Select(p => p.DefaultRates));
             var factory = FastTests.CreateBTCPayRateFactory();
             var fetcher = new RateFetcher(factory);
             var pairs =
                 provider
+                    .Where(c => c.CryptoCode is not null)
                     .Select(c => new CurrencyPair(c.CryptoCode, "USD"))
                     .ToHashSet();
 
@@ -408,7 +412,7 @@ retry:
                 }
             }
 
-            var rules = new StoreBlob().GetDefaultRateRules(provider.Select(p => p.DefaultRates));
+            var rules = new StoreBlob().GetDefaultRateRules(defaultRules);
             var result = fetcher.FetchRates(pairs, rules, null, cts.Token);
             foreach ((CurrencyPair key, Task<RateResult> value) in result)
             {
@@ -418,13 +422,22 @@ retry:
             }
         }
 
-        private IEnumerable<(string CryptoCode, DefaultRates DefaultRates)> CreateDefaultRates(ChainName chainName)
+        private IEnumerable<(string CryptoCode, DefaultRules DefaultRates)> CreateDefaultRates(ChainName chainName, bool exchangeRecommendation = false)
         {
-            var results = new List<(string CryptoCode, DefaultRates DefaultRates)>();
+            var results = new List<(string CryptoCode, DefaultRules DefaultRates)>();
             var prov = CreateNetworkProvider(chainName);
             foreach (var network in prov.GetAll())
             {
-                results.Add((network.CryptoCode, new DefaultRates(network.DefaultRateRules)));
+                results.Add((network.CryptoCode, new DefaultRules(network.DefaultRateRules)));
+            }
+            if (exchangeRecommendation)
+            {
+                ServiceCollection services = new ServiceCollection();
+                BTCPayServerServices.RegisterExchangeRecommendations(services);
+                foreach (var rule in services.BuildServiceProvider().GetRequiredService<IEnumerable<DefaultRules>>())
+                {
+                    results.Add((null, rule));
+                }
             }
             return results;
         }

BTCPayServer/Components/WalletNav/WalletNav.cs

@@ -31,7 +31,7 @@ namespace BTCPayServer.Components.WalletNav
         private readonly PaymentMethodHandlerDictionary _handlers;
         private readonly UIWalletsController _walletsController;
         private readonly CurrencyNameTable _currencies;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly RateFetcher _rateFetcher;
 
         public WalletNav(
@@ -39,14 +39,14 @@ namespace BTCPayServer.Components.WalletNav
             PaymentMethodHandlerDictionary handlers,
             UIWalletsController walletsController,
             CurrencyNameTable currencies,
-            IEnumerable<DefaultRates> defaultRates,
+            DefaultRulesCollection defaultRules,
             RateFetcher rateFetcher)
         {
             _walletProvider = walletProvider;
             _handlers = handlers;
             _walletsController = walletsController;
             _currencies = currencies;
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
             _rateFetcher = rateFetcher;
         }
 
@@ -76,7 +76,7 @@ namespace BTCPayServer.Components.WalletNav
 
             if (defaultCurrency != network.CryptoCode)
             {
-                var rule = store.GetStoreBlob().GetRateRules(_defaultRates)?.GetRuleFor(new Rating.CurrencyPair(network.CryptoCode, defaultCurrency));
+                var rule = store.GetStoreBlob().GetRateRules(_defaultRules)?.GetRuleFor(new Rating.CurrencyPair(network.CryptoCode, defaultCurrency));
                 var bid = rule is null ? null : (await _rateFetcher.FetchRate(rule, new StoreIdRateContext(walletId.StoreId), HttpContext.RequestAborted)).BidAsk?.Bid;
                 if (bid is decimal b)
                 {

BTCPayServer/Controllers/BitpayRateController.cs

@@ -31,7 +31,7 @@ namespace BTCPayServer.Controllers
 
         readonly RateFetcher _rateProviderFactory;
         readonly CurrencyNameTable _currencyNameTable;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly PaymentMethodHandlerDictionary _handlers;
         readonly StoreRepository _storeRepo;
         private readonly InvoiceRepository _invoiceRepository;
@@ -43,14 +43,14 @@ namespace BTCPayServer.Controllers
             StoreRepository storeRepo,
             InvoiceRepository invoiceRepository,
             CurrencyNameTable currencyNameTable,
-            IEnumerable<DefaultRates> defaultRates,
+            DefaultRulesCollection defaultRules,
             PaymentMethodHandlerDictionary handlers)
         {
             _rateProviderFactory = rateProviderFactory ?? throw new ArgumentNullException(nameof(rateProviderFactory));
             _storeRepo = storeRepo;
             _invoiceRepository = invoiceRepository;
             _currencyNameTable = currencyNameTable ?? throw new ArgumentNullException(nameof(currencyNameTable));
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
             _handlers = handlers;
         }
 
@@ -124,7 +124,7 @@ namespace BTCPayServer.Controllers
                 }
             }
 
-            var rules = store.GetStoreBlob().GetRateRules(_defaultRates);
+            var rules = store.GetStoreBlob().GetRateRules(_defaultRules);
             var pairs = new HashSet<CurrencyPair>();
             foreach (var currency in currencyPairs.Split(','))
             {

BTCPayServer/Controllers/GreenField/GreenfieldInvoiceController.cs

@@ -48,7 +48,7 @@ namespace BTCPayServer.Controllers.Greenfield
         private readonly Dictionary<PaymentMethodId, IPaymentLinkExtension> _paymentLinkExtensions;
         private readonly PayoutMethodHandlerDictionary _payoutHandlers;
         private readonly PaymentMethodHandlerDictionary _handlers;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
 
         public LanguageService LanguageService { get; }
 
@@ -62,7 +62,7 @@ namespace BTCPayServer.Controllers.Greenfield
             Dictionary<PaymentMethodId, IPaymentLinkExtension> paymentLinkExtensions,
             PayoutMethodHandlerDictionary payoutHandlers,
             PaymentMethodHandlerDictionary handlers,
-            IEnumerable<DefaultRates> defaultRates)
+            DefaultRulesCollection defaultRules)
         {
             _invoiceController = invoiceController;
             _invoiceRepository = invoiceRepository;
@@ -76,7 +76,7 @@ namespace BTCPayServer.Controllers.Greenfield
             _paymentLinkExtensions = paymentLinkExtensions;
             _payoutHandlers = payoutHandlers;
             _handlers = handlers;
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
             LanguageService = languageService;
         }
 
@@ -430,7 +430,7 @@ namespace BTCPayServer.Controllers.Greenfield
             var paidCurrency = Math.Round(cryptoPaid * paymentPrompt.Rate, cdCurrency.Divisibility);
             var rateResult = await _rateProvider.FetchRate(
                 new CurrencyPair(paymentPrompt.Currency, invoice.Currency),
-                store.GetStoreBlob().GetRateRules(_defaultRates), new StoreIdRateContext(storeId),
+                store.GetStoreBlob().GetRateRules(_defaultRules), new StoreIdRateContext(storeId),
 
 				cancellationToken
             );

BTCPayServer/Controllers/GreenField/GreenfieldStoreRatesConfigurationController.cs

@@ -27,16 +27,16 @@ namespace BTCPayServer.Controllers.GreenField
     public class GreenfieldStoreRateConfigurationController : ControllerBase
     {
         private readonly RateFetcher _rateProviderFactory;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly StoreRepository _storeRepository;
 
         public GreenfieldStoreRateConfigurationController(
             RateFetcher rateProviderFactory,
-			IEnumerable<DefaultRates> defaultRates,
+			DefaultRulesCollection defaultRules,
             StoreRepository storeRepository)
         {
             _rateProviderFactory = rateProviderFactory;
-			_defaultRates = defaultRates;
+			_defaultRules = defaultRules;
             _storeRepository = storeRepository;
         }
 
@@ -49,10 +49,10 @@ namespace BTCPayServer.Controllers.GreenField
 
             return Ok(new StoreRateConfiguration()
             {
-                EffectiveScript = blob.GetRateRules(_defaultRates, out var preferredExchange).ToString(),
+                EffectiveScript = blob.GetRateRules(_defaultRules, out var preferredExchange).ToString(),
                 Spread = blob.Spread * 100.0m,
                 IsCustomScript = blob.RateScripting,
-                PreferredSource = preferredExchange ? blob.PreferredExchange : null
+                PreferredSource = preferredExchange ? blob.GetPreferredExchange(_defaultRules) : null
             });
         }
 
@@ -118,7 +118,7 @@ namespace BTCPayServer.Controllers.GreenField
                 return this.CreateValidationError(ModelState);
             PopulateBlob(configuration, blob);
 
-            var rules = blob.GetRateRules(_defaultRates);
+            var rules = blob.GetRateRules(_defaultRules);
 
 
             var rateTasks = _rateProviderFactory.FetchRates(parsedCurrencyPairs, rules, new StoreIdRateContext(data.Id), CancellationToken.None);
@@ -156,7 +156,7 @@ namespace BTCPayServer.Controllers.GreenField
             {
                 if (string.IsNullOrEmpty(configuration.EffectiveScript))
                 {
-                    configuration.EffectiveScript = storeBlob.GetDefaultRateRules(_defaultRates).ToString();
+                    configuration.EffectiveScript = storeBlob.GetDefaultRateRules(_defaultRules).ToString();
                 }
 
                 if (!RateRules.TryParse(configuration.EffectiveScript, out var r))
@@ -182,12 +182,8 @@ $"You can't set the preferredSource if you are using custom scripts");
                     ModelState.AddModelError(nameof(configuration.EffectiveScript),
                     $"You can't set the effectiveScript if you aren't using custom scripts");
                 }
-                if (string.IsNullOrEmpty(configuration.PreferredSource))
+                if (!string.IsNullOrEmpty(configuration.PreferredSource))
                 {
-                    ModelState.AddModelError(nameof(configuration.PreferredSource),
-$"The preferredSource is required if you aren't using custom scripts");
-                }
-
                     configuration.PreferredSource = _rateProviderFactory
                         .RateProviderFactory
                         .AvailableRateProviders
@@ -202,6 +198,7 @@ $"The preferredSource is required if you aren't using custom scripts");
                     }
                 }
             }
+        }
 
         private static void PopulateBlob(StoreRateConfiguration configuration, StoreBlob storeBlob)
         {

BTCPayServer/Controllers/GreenField/GreenfieldStoreRatesController.cs

@@ -24,14 +24,14 @@ namespace BTCPayServer.Controllers.GreenField
     public class GreenfieldStoreRatesController : ControllerBase
     {
         private readonly RateFetcher _rateProviderFactory;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
 
         public GreenfieldStoreRatesController(
             RateFetcher rateProviderFactory,
-            IEnumerable<DefaultRates> defaultRates)
+            DefaultRulesCollection defaultRules)
         {
             _rateProviderFactory = rateProviderFactory;
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
         }
 
         [HttpGet("")]
@@ -62,7 +62,7 @@ namespace BTCPayServer.Controllers.GreenField
             }
 
 
-            var rules = blob.GetRateRules(_defaultRates);
+            var rules = blob.GetRateRules(_defaultRules);
 
 
             var rateTasks = _rateProviderFactory.FetchRates(parsedCurrencyPairs, rules, new StoreIdRateContext(data.Id), CancellationToken.None);

BTCPayServer/Controllers/UIInvoiceController.UI.cs

@@ -382,7 +382,7 @@ namespace BTCPayServer.Controllers
                     var paidCurrency = Math.Round(cryptoPaid * paymentMethod.Rate, cdCurrency.Divisibility);
                     model.CryptoAmountThen = cryptoPaid.RoundToSignificant(paymentMethod.Divisibility);
                     model.RateThenText = _displayFormatter.Currency(model.CryptoAmountThen, paymentMethodCurrency);
-                    rules = store.GetStoreBlob().GetRateRules(_defaultRates);
+                    rules = store.GetStoreBlob().GetRateRules(_defaultRules);
                     rateResult = await _RateProvider.FetchRate(
                         new CurrencyPair(paymentMethodCurrency, invoice.Currency), rules, new StoreIdRateContext(store.Id),
                         cancellationToken);
@@ -491,7 +491,7 @@ namespace BTCPayServer.Controllers
                                 return View("_RefundModal", model);
                             }
 
-                            rules = store.GetStoreBlob().GetRateRules(_defaultRates);
+                            rules = store.GetStoreBlob().GetRateRules(_defaultRules);
                             rateResult = await _RateProvider.FetchRate(
                                 new CurrencyPair(paymentMethodCurrency, model.CustomCurrency), rules, new StoreIdRateContext(store.Id),
                                 cancellationToken);

BTCPayServer/Controllers/UIInvoiceController.cs

@@ -52,7 +52,7 @@ namespace BTCPayServer.Controllers
         readonly BTCPayNetworkProvider _NetworkProvider;
         private readonly PayoutMethodHandlerDictionary _payoutHandlers;
         private readonly PaymentMethodHandlerDictionary _handlers;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly ApplicationDbContextFactory _dbContextFactory;
         private readonly PullPaymentHostedService _paymentHostedService;
         private readonly LanguageService _languageService;
@@ -94,7 +94,7 @@ namespace BTCPayServer.Controllers
             AppService appService,
             IFileService fileService,
             UriResolver uriResolver,
-            IEnumerable<DefaultRates> defaultRates,
+            DefaultRulesCollection defaultRules,
             IAuthorizationService authorizationService,
             TransactionLinkProviders transactionLinkProviders,
             Dictionary<PaymentMethodId, IPaymentModelExtension> paymentModelExtensions,
@@ -125,7 +125,7 @@ namespace BTCPayServer.Controllers
             _viewProvider = viewProvider;
             _fileService = fileService;
             _uriResolver = uriResolver;
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
             _appService = appService;
         }
 
@@ -297,7 +297,7 @@ namespace BTCPayServer.Controllers
 
         private async Task FetchRates(InvoiceCreationContext context, CancellationToken cancellationToken)
         {
-            var rateRules = context.StoreBlob.GetRateRules(_defaultRates);
+            var rateRules = context.StoreBlob.GetRateRules(_defaultRules);
             await context.FetchingRates(_RateProvider, rateRules, cancellationToken);
         }
     }

BTCPayServer/Controllers/UIStoresController.Rates.cs

@@ -14,6 +14,7 @@ using BTCPayServer.Rating;
 using BTCPayServer.Services.Rates;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
+using static BTCPayServer.Lightning.Eclair.Models.ChannelResponse;
 
 namespace BTCPayServer.Controllers;
 
@@ -22,17 +23,9 @@ public partial class UIStoresController
     [HttpGet("{storeId}/rates")]
     public IActionResult Rates()
     {
-        var exchanges = GetSupportedExchanges().ToList();
         var storeBlob = CurrentStore.GetStoreBlob();
         var vm = new RatesViewModel();
-        vm.SetExchangeRates(exchanges, storeBlob.PreferredExchange ?? storeBlob.GetRecommendedExchange());
+        FillFromStore(vm, storeBlob);
-        vm.Spread = (double)(storeBlob.Spread * 100m);
-        vm.StoreId = CurrentStore.Id;
-        vm.Script = storeBlob.GetRateRules(_defaultRates).ToString();
-        vm.DefaultScript = storeBlob.GetDefaultRateRules(_defaultRates).ToString();
-        vm.AvailableExchanges = exchanges;
-        vm.DefaultCurrencyPairs = storeBlob.GetDefaultCurrencyPairString();
-        vm.ShowScripting = storeBlob.RateScripting;
         return View(vm);
     }
 
@@ -48,9 +41,6 @@ public partial class UIStoresController
         {
             return RedirectToAction(nameof(ShowRateRules), new { scripting = false, storeId = model.StoreId });
         }
-
-        var exchanges = GetSupportedExchanges().ToList();
-        model.SetExchangeRates(exchanges, model.PreferredExchange ?? HttpContext.GetStoreData().GetStoreBlob().GetRecommendedExchange());
         model.StoreId = storeId ?? model.StoreId;
         CurrencyPair[]? currencyPairs = null;
         try
@@ -70,22 +60,10 @@ public partial class UIStoresController
         }
         if (model.PreferredExchange != null)
             model.PreferredExchange = model.PreferredExchange.Trim().ToLowerInvariant();
+        if (string.IsNullOrEmpty(model.PreferredExchange))
+            model.PreferredExchange = null;
 
         var blob = CurrentStore.GetStoreBlob();
-        model.DefaultScript = blob.GetDefaultRateRules(_defaultRates).ToString();
-        model.AvailableExchanges = exchanges;
-
-        blob.PreferredExchange = model.PreferredExchange;
-        blob.Spread = (decimal)model.Spread / 100.0m;
-        blob.DefaultCurrencyPairs = currencyPairs;
-        if (!model.ShowScripting)
-        {
-            if (!exchanges.Any(provider => provider.Id.Equals(model.PreferredExchange, StringComparison.InvariantCultureIgnoreCase)))
-            {
-                ModelState.AddModelError(nameof(model.PreferredExchange), $"Unsupported exchange ({model.RateSource})");
-                return View(model);
-            }
-        }
         RateRules? rules;
         if (model.ShowScripting)
         {
@@ -94,17 +72,20 @@ public partial class UIStoresController
                 errors ??= [];
                 var errorString = string.Join(", ", errors.ToArray());
                 ModelState.AddModelError(nameof(model.Script), $"Parsing error ({errorString})");
+                FillFromStore(model, blob);
                 return View(model);
             }
             else
             {
                 blob.RateScript = rules.ToString();
                 ModelState.Remove(nameof(model.Script));
-                model.Script = blob.RateScript;
             }
         }
-        rules = blob.GetRateRules(_defaultRates);
+        blob.PreferredExchange = model.PreferredExchange;
-
+        blob.Spread = (decimal)model.Spread / 100.0m;
+        blob.DefaultCurrencyPairs = currencyPairs;
+        FillFromStore(model, blob);
+        rules = blob.GetRateRules(_defaultRules);
         if (command == "Test")
         {
             if (string.IsNullOrWhiteSpace(model.ScriptTest))
@@ -142,6 +123,12 @@ public partial class UIStoresController
             return View(model);
         }
 
+        if (model.PreferredExchange is not null && !model.AvailableExchanges.Any(a => a.Id == model.PreferredExchange))
+        {
+            ModelState.AddModelError(nameof(model.PreferredExchange), $"Unsupported exchange");
+            return View(model);
+        }
+
         // command == Save
         if (CurrentStore.SetStoreBlob(blob))
         {
@@ -175,16 +162,29 @@ public partial class UIStoresController
     {
         var blob = CurrentStore.GetStoreBlob();
         blob.RateScripting = scripting;
-        blob.RateScript = blob.GetDefaultRateRules(_defaultRates).ToString();
+        blob.RateScript = blob.GetDefaultRateRules(_defaultRules).ToString();
         CurrentStore.SetStoreBlob(blob);
         await _storeRepo.UpdateStore(CurrentStore);
         TempData[WellKnownTempData.SuccessMessage] = "Rate rules scripting " + (scripting ? "activated" : "deactivated");
         return RedirectToAction(nameof(Rates), new { storeId = CurrentStore.Id });
     }
 
-    private IEnumerable<RateSourceInfo> GetSupportedExchanges()
+    private void FillFromStore(RatesViewModel vm, StoreBlob storeBlob)
     {
-        return _rateFactory.RateProviderFactory.AvailableRateProviders
+        var sources = _rateFactory.RateProviderFactory.AvailableRateProviders
             .OrderBy(s => s.DisplayName, StringComparer.OrdinalIgnoreCase);
+        vm.AvailableExchanges = sources;
+        var exchange = storeBlob.GetPreferredExchange(_defaultRules);
+        var chosenSource = sources.First(r => r.Id == exchange);
+        vm.Exchanges = UIUserStoresController.GetExchangesSelectList(_rateFactory, _defaultRules, storeBlob);
+        vm.PreferredExchange = vm.Exchanges.SelectedValue as string;
+        vm.PreferredResolvedExchange = chosenSource.Id;
+        vm.RateSource = chosenSource.Url;
+        vm.Spread = (double)(storeBlob.Spread * 100m);
+        vm.StoreId = CurrentStore.Id;
+        vm.Script = storeBlob.GetRateRules(_defaultRules).ToString();
+        vm.DefaultScript = storeBlob.GetDefaultRateRules(_defaultRules).ToString();
+        vm.DefaultCurrencyPairs = storeBlob.GetDefaultCurrencyPairString();
+        vm.ShowScripting = storeBlob.RateScripting;
     }
 }

BTCPayServer/Controllers/UIStoresController.cs

@@ -55,7 +55,7 @@ public partial class UIStoresController : Controller
         IOptions<LightningNetworkOptions> lightningNetworkOptions,
         IOptions<ExternalServicesOptions> externalServiceOptions,
         IHtmlHelper html,
-        IEnumerable<DefaultRates> defaultRates,
+        DefaultRulesCollection defaultRules,
         EmailSenderFactory emailSenderFactory,
         WalletFileParsers onChainWalletParsers,
         UriResolver uriResolver,
@@ -85,7 +85,7 @@ public partial class UIStoresController : Controller
         _settingsRepository = settingsRepository;
         _eventAggregator = eventAggregator;
         _html = html;
-        _defaultRates = defaultRates;
+        _defaultRules = defaultRules;
         _dataProtector = dataProtector.CreateProtector("ConfigProtector");
         _webhookNotificationManager = webhookNotificationManager;
         _lightningNetworkOptions = lightningNetworkOptions.Value;
@@ -104,7 +104,7 @@ public partial class UIStoresController : Controller
     private readonly ExplorerClientProvider _explorerProvider;
     private readonly LanguageService _langService;
     private readonly PaymentMethodHandlerDictionary _handlers;
-    private readonly IEnumerable<DefaultRates> _defaultRates;
+    private readonly DefaultRulesCollection _defaultRules;
     private readonly PoliciesSettings _policiesSettings;
     private readonly IAuthorizationService _authorizationService;
     private readonly AppService _appService;

BTCPayServer/Controllers/UIUserStoresController.cs

@@ -23,17 +23,20 @@ namespace BTCPayServer.Controllers
         private readonly StoreRepository _repo;
         private readonly SettingsRepository _settingsRepository;
         private readonly UserManager<ApplicationUser> _userManager;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly RateFetcher _rateFactory;
         public string CreatedStoreId { get; set; }
 
         public UIUserStoresController(
             UserManager<ApplicationUser> userManager,
+			DefaultRulesCollection defaultRules,
             StoreRepository storeRepository,
             RateFetcher rateFactory,
             SettingsRepository settingsRepository)
         {
             _repo = storeRepository;
             _userManager = userManager;
+            _defaultRules = defaultRules;
             _rateFactory = rateFactory;
             _settingsRepository = settingsRepository;
         }
@@ -81,7 +84,7 @@ namespace BTCPayServer.Controllers
             {
                 var stores = await _repo.GetStoresByUserId(GetUserId());
                 vm.IsFirstStore = !stores.Any();
-                vm.Exchanges = GetExchangesSelectList(vm.PreferredExchange);
+                vm.Exchanges = GetExchangesSelectList(null);
                 return View(vm);
             }
 
@@ -124,14 +127,19 @@ namespace BTCPayServer.Controllers
 
         private string GetUserId() => _userManager.GetUserId(User);
 
-        private SelectList GetExchangesSelectList(string selected)
+		private SelectList GetExchangesSelectList(StoreBlob storeBlob) => GetExchangesSelectList(_rateFactory, _defaultRules, storeBlob);
+		internal static SelectList GetExchangesSelectList(RateFetcher rateFetcher, DefaultRulesCollection defaultRules, StoreBlob storeBlob)
 		{
-            var exchanges = _rateFactory.RateProviderFactory
+			if (storeBlob is null)
+				storeBlob = new StoreBlob();
+			var defaultExchange = defaultRules.GetRecommendedExchange(storeBlob.DefaultCurrency);
+			var exchanges = rateFetcher.RateProviderFactory
 				.AvailableRateProviders
 				.OrderBy(s => s.Id, StringComparer.OrdinalIgnoreCase)
 				.ToList();
-            exchanges.Insert(0, new (null, "Recommended", ""));
+			var exchange = exchanges.First(e => e.Id == defaultExchange);
-            var chosen = exchanges.FirstOrDefault(f => f.Id == selected) ?? exchanges.First();
+			exchanges.Insert(0, new(null, $"Recommendation ({exchange.DisplayName})", ""));
+			var chosen = exchanges.FirstOrDefault(f => f.Id == storeBlob.PreferredExchange) ?? exchanges.First();
 			return new SelectList(exchanges, nameof(chosen.Id), nameof(chosen.DisplayName), chosen.Id);
 		}
 	}

BTCPayServer/Controllers/UIWalletsController.cs

@@ -73,7 +73,7 @@ namespace BTCPayServer.Controllers
         private readonly PayjoinClient _payjoinClient;
         private readonly LabelService _labelService;
         private readonly PaymentMethodHandlerDictionary _handlers;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly Dictionary<PaymentMethodId, IPaymentModelExtension> _paymentModelExtensions;
         private readonly TransactionLinkProviders _transactionLinkProviders;
         private readonly PullPaymentHostedService _pullPaymentHostedService;
@@ -100,14 +100,14 @@ namespace BTCPayServer.Controllers
                                  IServiceProvider serviceProvider,
                                  PullPaymentHostedService pullPaymentHostedService,
                                  LabelService labelService,
-                                 IEnumerable<DefaultRates> defaultRates,
+                                 DefaultRulesCollection defaultRules,
                                  PaymentMethodHandlerDictionary handlers,
                                  Dictionary<PaymentMethodId, IPaymentModelExtension> paymentModelExtensions,
                                  TransactionLinkProviders transactionLinkProviders)
         {
             _currencyTable = currencyTable;
             _labelService = labelService;
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
             _handlers = handlers;
             _paymentModelExtensions = paymentModelExtensions;
             _transactionLinkProviders = transactionLinkProviders;
@@ -459,7 +459,7 @@ namespace BTCPayServer.Controllers
             if (network == null || network.ReadonlyWallet)
                 return NotFound();
             var storeData = store.GetStoreBlob();
-            var rateRules = store.GetStoreBlob().GetRateRules(_defaultRates);
+            var rateRules = store.GetStoreBlob().GetRateRules(_defaultRules);
             rateRules.Spread = 0.0m;
             var currencyPair = new Rating.CurrencyPair(walletId.CryptoCode, storeData.DefaultCurrency);
             double.TryParse(defaultAmount, out var amount);

BTCPayServer/Data/StoreBlob.cs

@@ -102,7 +102,19 @@ namespace BTCPayServer.Data
 
         public decimal Spread { get; set; } = 0.0m;
 
+        /// <summary>
+        /// This may be null. Use <see cref="GetPreferredExchange(DefaultRulesCollection)"/> instead if you want to return a valid exchange
+        /// </summary>
         public string PreferredExchange { get; set; }
+        /// <summary>
+        /// Use the preferred exchange of the store, or the recommended exchange from the default currency
+        /// </summary>
+        /// <param name="defaultRules"></param>
+        /// <returns></returns>
+        public string GetPreferredExchange(DefaultRulesCollection defaultRules)
+        {
+            return string.IsNullOrEmpty(PreferredExchange) ? defaultRules.GetRecommendedExchange(DefaultCurrency) : PreferredExchange;
+        }
 
         public List<PaymentMethodCriteria> PaymentMethodCriteria { get; set; }
         public string HtmlTitle { get; set; }
@@ -135,18 +147,18 @@ namespace BTCPayServer.Data
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
         public double PaymentTolerance { get; set; }
 
-        public BTCPayServer.Rating.RateRules GetRateRules(IEnumerable<DefaultRates> defaultRates)
+        public BTCPayServer.Rating.RateRules GetRateRules(DefaultRulesCollection defaultRules)
         {
-            return GetRateRules(defaultRates, out _);
+            return GetRateRules(defaultRules, out _);
         }
-        public BTCPayServer.Rating.RateRules GetRateRules(IEnumerable<DefaultRates> defaultRates, out bool preferredSource)
+        public BTCPayServer.Rating.RateRules GetRateRules(DefaultRulesCollection defaultRules, out bool preferredSource)
         {
             if (!RateScripting ||
                 string.IsNullOrEmpty(RateScript) ||
                 !BTCPayServer.Rating.RateRules.TryParse(RateScript, out var rules))
             {
                 preferredSource = true;
-                return GetDefaultRateRules(defaultRates);
+                return GetDefaultRateRules(defaultRules);
             }
             else
             {
@@ -156,34 +168,13 @@ namespace BTCPayServer.Data
             }
         }
 
-        public RateRules GetDefaultRateRules(IEnumerable<DefaultRates> defaultRates)
+        public RateRules GetDefaultRateRules(DefaultRulesCollection defaultRules)
         {
-            var preferredExchange = string.IsNullOrEmpty(PreferredExchange) ? GetRecommendedExchange() : PreferredExchange;
+            var rules = defaultRules.WithPreferredExchange(PreferredExchange);
-            var preferredExchangeRule = RateRules.Parse($"X_X = {preferredExchange}(X_X);");
-            var rules = RateRules.Combine(defaultRates.Select(r => r.Rules).Concat([preferredExchangeRule]).ToArray());
             rules.Spread = Spread;
             return rules;
         }
 
-        public static JObject RecommendedExchanges = new()
-        {
-            { "EUR", "kraken" },
-            { "USD", "kraken" },
-            { "GBP", "kraken" },
-            { "CHF", "kraken" },
-            { "GTQ", "bitpay" },
-            { "COP", "yadio" },
-            { "ARS", "yadio" },
-            { "JPY", "bitbank" },
-            { "TRY", "btcturk" },
-            { "UGX", "yadio"},
-            { "RSD", "bitpay"},
-            { "NGN", "bitnob"}
-        };
-
-        public string GetRecommendedExchange() =>
-            RecommendedExchanges.Property(DefaultCurrency)?.Value.ToString() ?? "coingecko";
-
         [Obsolete("Use GetExcludedPaymentMethods instead")]
         public string[] ExcludedPaymentMethods { get; set; }
 

BTCPayServer/Data/StoreDataExtensions.cs

@@ -53,8 +53,6 @@ namespace BTCPayServer.Data
         {
             ArgumentNullException.ThrowIfNull(storeData);
             var result = storeData.StoreBlob == null ? new StoreBlob() : new Serializer(null).ToObject<StoreBlob>(storeData.StoreBlob);
-            if (result.PreferredExchange == null)
-                result.PreferredExchange = result.GetRecommendedExchange();
             if (result.PaymentMethodCriteria is null)
                 result.PaymentMethodCriteria = new List<PaymentMethodCriteria>();
             result.PaymentMethodCriteria.RemoveAll(criteria => criteria?.PaymentMethod is null);

BTCPayServer/DefaultRates.cs

@@ -1,11 +0,0 @@
-using System;
-using System.Linq;
-using BTCPayServer.Rating;
-
-namespace BTCPayServer;
-public record DefaultRates(RateRules Rules)
-{
-    public DefaultRates(string[] Rules) : this(RateRules.Combine(Rules.Select(r => RateRules.Parse(r)).ToArray()))
-    {
-    }
-}

BTCPayServer/DefaultRules.cs

@@ -0,0 +1,72 @@
+#nullable enable
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using BTCPayServer.Data;
+using BTCPayServer.Rating;
+using Newtonsoft.Json.Linq;
+
+namespace BTCPayServer;
+public record DefaultRules(RateRules Rules)
+{
+    public record Recommendation : DefaultRules
+    {
+        public Recommendation(string currency, string exchange) : base($"X_{currency.ToUpperInvariant()} = {exchange.ToLowerInvariant()}(X_{currency.ToUpperInvariant()});")
+        {
+            Currency = currency.ToUpperInvariant();
+            Exchange = exchange.ToLowerInvariant();
+        }
+        public string Currency { get; }
+        public string Exchange { get; }
+    }
+    public const int HardcodedRecommendedExchangeOrder = 10;
+    public DefaultRules(string Rules) : this(RateRules.Parse(Rules))
+    {
+    }
+    public DefaultRules(string[] Rules) : this(RateRules.Combine(Rules.Select(r => RateRules.Parse(r)).ToArray()))
+    {
+    }
+    /// <summary>
+    /// Rules are applied in order, the lower the order, the higher the priority. Default is 0.
+    /// </summary>
+    public int Order { get; set; }
+}
+
+public class DefaultRulesCollection
+{
+    public DefaultRulesCollection(IEnumerable<DefaultRules> defaultRules)
+    {
+        defaultRules = defaultRules.OrderBy(o => o.Order).ToList();
+        Consolidated = RateRules.Combine(defaultRules.Select(r => r.Rules));
+        ConsolidatedWithoutRecommendation = RateRules.Combine(defaultRules.Where(r => r is not DefaultRules.Recommendation).Select(r => r.Rules));
+        var rules = Consolidated.ToString();
+
+        foreach (var recommendation in defaultRules.OfType<DefaultRules.Recommendation>())
+        {
+            RecommendedExchanges.TryAdd(recommendation.Currency, recommendation.Exchange);
+        }
+    }
+
+    public RateRules Consolidated { get; private set; }
+    public RateRules ConsolidatedWithoutRecommendation { get; private set; }
+
+    public RateRules WithPreferredExchange(string? preferredExchange)
+    {
+        if (string.IsNullOrEmpty(preferredExchange))
+        {
+            return Consolidated;
+        }
+        else
+        {
+            var catchAll = RateRules.Parse($"X_X = {preferredExchange}(X_X);");
+            return RateRules.Combine([catchAll, ConsolidatedWithoutRecommendation]);
+        }
+    }
+
+    public Dictionary<string, string> RecommendedExchanges { get; } = new Dictionary<string, string>();
+
+    public string GetRecommendedExchange(string currency) =>
+        RecommendedExchanges.TryGetValue(currency, out var ex) ? ex : "coingecko";
+
+    public override string ToString() => Consolidated.ToString();
+}

BTCPayServer/HostedServices/PullPaymentHostedService.cs

@@ -279,7 +279,7 @@ namespace BTCPayServer.HostedServices
             EventAggregator eventAggregator,
             BTCPayNetworkProvider networkProvider,
             PayoutMethodHandlerDictionary handlers,
-            IEnumerable<DefaultRates> defaultRates,
+            DefaultRulesCollection defaultRules,
             NotificationSender notificationSender,
             RateFetcher rateFetcher,
             ILogger<PullPaymentHostedService> logger,
@@ -292,7 +292,7 @@ namespace BTCPayServer.HostedServices
             _eventAggregator = eventAggregator;
             _networkProvider = networkProvider;
             _handlers = handlers;
-            _defaultRates = defaultRates;
+            _defaultRules = defaultRules;
             _notificationSender = notificationSender;
             _rateFetcher = rateFetcher;
             _logger = logger;
@@ -306,7 +306,7 @@ namespace BTCPayServer.HostedServices
         private readonly EventAggregator _eventAggregator;
         private readonly BTCPayNetworkProvider _networkProvider;
         private readonly PayoutMethodHandlerDictionary _handlers;
-        private readonly IEnumerable<DefaultRates> _defaultRates;
+        private readonly DefaultRulesCollection _defaultRules;
         private readonly NotificationSender _notificationSender;
         private readonly RateFetcher _rateFetcher;
         private readonly ILogger<PullPaymentHostedService> _logger;
@@ -392,7 +392,7 @@ namespace BTCPayServer.HostedServices
                 if (explicitRateRule is null)
                 {
                     var storeBlob = payout.StoreData.GetStoreBlob();
-                    var rules = storeBlob.GetRateRules(_defaultRates);
+                    var rules = storeBlob.GetRateRules(_defaultRules);
                     rules.Spread = 0.0m;
                     rule = rules.GetRuleFor(currencyPair);
                 }

BTCPayServer/Hosting/BTCPayServerServices.cs

@@ -403,6 +403,8 @@ o.GetRequiredService<IEnumerable<IPaymentLinkExtension>>().ToDictionary(o => o.P
             services.AddSingleton<NotificationManager>();
             services.AddScoped<NotificationSender>();
 
+            RegisterExchangeRecommendations(services);
+            services.AddSingleton<DefaultRulesCollection>();
             services.AddSingleton<IHostedService, NBXplorerWaiters>();
             services.AddSingleton<IHostedService, InvoiceEventSaverService>();
             services.AddSingleton<IHostedService, BitpayIPNSender>();
@@ -504,6 +506,30 @@ o.GetRequiredService<IEnumerable<IPaymentLinkExtension>>().ToDictionary(o => o.P
             return services;
         }
 
+        public static void RegisterExchangeRecommendations(IServiceCollection services)
+        {
+            foreach (var rule in new Dictionary<string, string>()
+            {
+                { "EUR", "kraken" },
+                { "USD", "kraken" },
+                { "GBP", "kraken" },
+                { "CHF", "kraken" },
+                { "GTQ", "bitpay" },
+                { "COP", "yadio" },
+                { "ARS", "yadio" },
+                { "JPY", "bitbank" },
+                { "TRY", "btcturk" },
+                { "UGX", "yadio"},
+                { "RSD", "bitpay"},
+                { "NGN", "bitnob"}
+            })
+            {
+                var r = new DefaultRules.Recommendation(rule.Key, rule.Value);
+                r.Order = DefaultRules.HardcodedRecommendedExchangeOrder;
+                services.AddSingleton<DefaultRules>(r);
+            }
+        }
+
         public static void AddOnchainWalletParsers(IServiceCollection services)
         {
             services.AddSingleton<WalletFileParsers>();
@@ -563,13 +589,13 @@ o.GetRequiredService<IEnumerable<IPaymentLinkExtension>>().ToDictionary(o => o.P
         }
         public static IServiceCollection AddBTCPayNetwork(this IServiceCollection services, BTCPayNetworkBase network)
         {
-            services.AddSingleton(new DefaultRates(network.DefaultRateRules));
+            services.AddSingleton(new DefaultRules(network.DefaultRateRules));
             services.AddSingleton<BTCPayNetworkBase>(network);
             return services;
         }
         public static IServiceCollection AddBTCPayNetwork(this IServiceCollection services, BTCPayNetwork network)
         {
-            services.AddSingleton(new DefaultRates(network.DefaultRateRules));
+            services.AddSingleton(new DefaultRules(network.DefaultRateRules));
             // BTC
             {
                 var pmi = PaymentTypes.CHAIN.GetPaymentMethodId(network.CryptoCode);

BTCPayServer/Models/StoreViewModels/RatesViewModel.cs

@@ -17,15 +17,6 @@ namespace BTCPayServer.Models.StoreViewModels
             public bool Error { get; set; }
         }
 
-        public void SetExchangeRates(IEnumerable<RateSourceInfo> supportedList, string preferredExchange)
-        {
-            supportedList = supportedList.ToArray();
-            var chosen = supportedList.FirstOrDefault(f => f.Id == preferredExchange) ?? supportedList.FirstOrDefault();
-            Exchanges = new SelectList(supportedList, nameof(chosen.Id), nameof(chosen.DisplayName), chosen);
-            PreferredExchange = chosen?.Id;
-            RateSource = chosen?.Url;
-        }
-
         public List<TestResultViewModel> TestRateRules { get; set; }
 
         public SelectList Exchanges { get; set; }
@@ -47,6 +38,7 @@ namespace BTCPayServer.Models.StoreViewModels
 
         [Display(Name = "Preferred Price Source")]
         public string PreferredExchange { get; set; }
+        public string PreferredResolvedExchange { get; set; }
 
         public string RateSource { get; set; }
     }

BTCPayServer/Views/UIServer/Policies.cshtml

@@ -187,7 +187,7 @@
             <h4 class="mt-5">Customization</h4>
             <div class="form-group mb-3">
                 <label asp-for="DefaultCurrency" class="form-label"></label>
-                <input asp-for="DefaultCurrency" placeholder="Default Store Currency" class="form-control" currency-selection  />
+				<input asp-for="DefaultCurrency" placeholder="@StoreBlob.StandardDefaultCurrency" class="form-control" currency-selection />
             </div>
             <div class="form-group mb-5">
                 <label asp-for="RootAppId" class="form-label"></label>

BTCPayServer/Views/UIStores/Rates.cshtml

@@ -138,7 +138,7 @@ X_X = kraken(X_X);</code></pre>
                     <select asp-for="PreferredExchange" asp-items="Model.Exchanges" class="form-select"></select>
                     <span asp-validation-for="PreferredExchange" class="text-danger"></span>
                     <div id="PreferredExchangeHelpBlock" class="form-text">
-                        Current Rates source is <a href="@Model.RateSource" target="_blank" rel="noreferrer noopener">@Model.PreferredExchange</a>.
+                        Current Rates source is <a href="@Model.RateSource" target="_blank" rel="noreferrer noopener">@Model.PreferredResolvedExchange</a>.
                     </div>
                 </div>
             }

BTCPayServer/Views/UIUserStores/CreateStore.cshtml

@@ -1,4 +1,5 @@
-@model BTCPayServer.Models.StoreViewModels.CreateStoreViewModel
+@model BTCPayServer.Models.StoreViewModels.CreateStoreViewModel
+@inject DefaultRulesCollection DefaultRules
 @{
     Layout = Model.IsFirstStore ? "_LayoutWizard" : "_Layout";
     ViewData.SetActivePage(StoreNavPages.Create, Model.IsFirstStore ? "Create your first store" : "Create a new store");
@@ -7,12 +8,12 @@
 @section PageFootContent {
     <partial name="_ValidationScriptsPartial" />
     <script>
-	  const exchanges = @Safe.Json(StoreBlob.RecommendedExchanges);
+	  const exchanges = @Safe.Json(DefaultRules.RecommendedExchanges);
 	  const recommended = document.querySelector("#PreferredExchange option[value='']")
 	  const updateRecommended = currency => {
 		  const source = exchanges[currency] || 'coingecko'
 		  const name = source.charAt(0).toUpperCase() + source.slice(1)
-		  recommended.innerText = `${name} (Recommended)`
+		  recommended.innerText = `Recommendation (${name})`
 	  }
 	  updateRecommended(@Safe.Json(Model.DefaultCurrency))
 	  delegate('change', '#DefaultCurrency', e => updateRecommended(e.target.value))