[Feature] Can configure fallback rates

BTCPayServer/Controllers/UIStoresController.Rates.cs

@@ -6,6 +6,7 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using BTCPayServer.Abstractions.Constants;
+using BTCPayServer.Abstractions.Extensions;
 using BTCPayServer.Abstractions.Models;
 using BTCPayServer.Client;
 using BTCPayServer.Data;
@@ -24,7 +25,7 @@ public partial class UIStoresController
     {
         var storeBlob = CurrentStore.GetStoreBlob();
         var vm = new RatesViewModel();
-        FillFromStore(vm, storeBlob);
+        SetViewModel(vm, storeBlob);
         return View(vm);
     }
 
@@ -32,61 +33,63 @@ public partial class UIStoresController
     [Authorize(Policy = Policies.CanModifyStoreSettings, AuthenticationSchemes = AuthenticationSchemes.Cookie)]
     public async Task<IActionResult> Rates(RatesViewModel model, string? command = null, string? storeId = null, CancellationToken cancellationToken = default)
     {
-        if (command == "scripting-on")
-        {
-            return RedirectToAction(nameof(ShowRateRules), new { scripting = true, storeId = model.StoreId });
-        }
-        if (command == "scripting-off")
-        {
-            return RedirectToAction(nameof(ShowRateRules), new { scripting = false, storeId = model.StoreId });
-        }
         model.StoreId = storeId ?? model.StoreId;
-        CurrencyPair[]? currencyPairs = null;
+
+        var storeBlob = CurrentStore.GetStoreBlob();
         try
         {
-            currencyPairs = model.DefaultCurrencyPairs?
+            var currencyPairs = model.DefaultCurrencyPairs?
                 .Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
                 .Select(p => CurrencyPair.Parse(p))
                 .ToArray();
+            storeBlob.DefaultCurrencyPairs = currencyPairs;
         }
         catch
         {
             ModelState.AddModelError(nameof(model.DefaultCurrencyPairs), StringLocalizer["Invalid currency pairs (should be for example: {0})", "BTC_USD,BTC_CAD,BTC_JPY"]);
         }
+        storeBlob.Spread = (decimal)model.Spread / 100.0m;
+
+        var primarySettings = storeBlob.PrimaryRateSettings ??= new();
+        FillToStore(primarySettings, model.PrimarySource);
+        if (model.HasFallback)
+        {
+            storeBlob.FallbackRateSettings = new();
+            FillToStore(storeBlob.FallbackRateSettings, model.FallbackSource);
+        }
+        else
+        {
+            storeBlob.FallbackRateSettings = null;
+        }
+
         if (!ModelState.IsValid)
         {
+            SetViewModel(model, storeBlob);
             return View(model);
         }
-        if (model.PreferredExchange != null)
-            model.PreferredExchange = model.PreferredExchange.Trim().ToLowerInvariant();
-        if (string.IsNullOrEmpty(model.PreferredExchange))
-            model.PreferredExchange = null;
 
-        var blob = CurrentStore.GetStoreBlob();
-        RateRules? rules;
-        if (model.ShowScripting)
+        if (command is "scripting-toggle-fallback" or "scripting-toggle-primary")
         {
-            if (!RateRules.TryParse(model.Script, out rules, out var errors))
+            var isFallback = command is "scripting-toggle-fallback";
+            var rateSettings = storeBlob.GetOrCreateRateSettings(isFallback);
+            rateSettings.RateScripting = !rateSettings.RateScripting;
+            rateSettings.RateScript = rateSettings.GetDefaultRateRules(_defaultRules, storeBlob.Spread).ToString();
+            CurrentStore.SetStoreBlob(storeBlob);
+            await _storeRepo.UpdateStore(CurrentStore);
+            if (rateSettings.RateScripting)
             {
-                errors ??= [];
-                var errorString = string.Join(", ", errors.ToArray());
-                ModelState.AddModelError(nameof(model.Script), StringLocalizer["Parsing error: {0}", errorString]);
-                FillFromStore(model, blob);
-                return View(model);
+                TempData[WellKnownTempData.SuccessMessage] = StringLocalizer["Rate rules scripting activated"].Value;
             }
             else
             {
-                blob.RateScript = rules.ToString();
-                ModelState.Remove(nameof(model.Script));
+                TempData[WellKnownTempData.SuccessMessage] = StringLocalizer["Rate rules scripting deactivated"].Value;
             }
+
+            return RedirectToAction(nameof(Rates), null, new { storeId = CurrentStore.Id });
         }
-        blob.PreferredExchange = model.PreferredExchange;
-        blob.Spread = (decimal)model.Spread / 100.0m;
-        blob.DefaultCurrencyPairs = currencyPairs;
-        FillFromStore(model, blob);
-        rules = blob.GetRateRules(_defaultRules);
-        if (command == "Test")
+        else if (command == "Test")
         {
+            SetViewModel(model, storeBlob);
             if (string.IsNullOrWhiteSpace(model.ScriptTest))
             {
                 ModelState.AddModelError(nameof(model.ScriptTest), StringLocalizer["Fill out currency pair to test for (like {0})", "BTC_USD,BTC_CAD"]);
@@ -104,32 +107,34 @@ public partial class UIStoresController
                 }
                 pairs.Add(currencyPair);
             }
-
-            var fetchs = _rateFactory.FetchRates(pairs.ToHashSet(), rules, new StoreIdRateContext(model.StoreId), cancellationToken);
             var testResults = new List<RatesViewModel.TestResultViewModel>();
-            foreach (var fetch in fetchs)
+            foreach (var isFallback in new[]{ false, true })
             {
-                var testResult = await (fetch.Value);
-                testResults.Add(new RatesViewModel.TestResultViewModel
+                var blob = storeBlob.GetRateSettings(isFallback);
+                if (blob is null)
+                    continue;
+                var rules = blob.GetRateRules(_defaultRules, storeBlob.Spread);
+                var fetchs = _rateFactory.FetchRates(pairs.ToHashSet(), rules, new StoreIdRateContext(model.StoreId), cancellationToken);
+                foreach (var fetch in fetchs)
                 {
-                    CurrencyPair = fetch.Key.ToString(),
-                    Error = testResult.Errors.Count != 0,
-                    Rule = testResult.Errors.Count == 0 ? testResult.Rule + " = " + testResult.BidAsk.Bid.ToString(CultureInfo.InvariantCulture)
-                        : testResult.EvaluatedRule
-                });
+                    var testResult = await (fetch.Value);
+                    testResults.Add(new RatesViewModel.TestResultViewModel
+                    {
+                        CurrencyPair = isFallback ? $"{fetch.Key} (fallback)" : fetch.Key.ToString(),
+                        Error = testResult.Errors.Count != 0,
+                        Rule = testResult.Errors.Count == 0
+                            ? testResult.Rule + " = " + testResult.BidAsk.Bid.ToString(CultureInfo.InvariantCulture)
+                            : testResult.EvaluatedRule
+                    });
+                }
             }
-            model.TestRateRules = testResults;
-            return View(model);
-        }
-
-        if (model.PreferredExchange is not null && !model.AvailableExchanges.Any(a => a.Id == model.PreferredExchange))
-        {
-            ModelState.AddModelError(nameof(model.PreferredExchange), StringLocalizer["Unsupported exchange"]);
+            model.TestRateRules = testResults.OrderBy(o => o.CurrencyPair).ToList();
+            model.Hash = "#TestResult";
             return View(model);
         }
 
         // command == Save
-        if (CurrentStore.SetStoreBlob(blob))
+        if (CurrentStore.SetStoreBlob(storeBlob))
         {
             await _storeRepo.UpdateStore(CurrentStore);
             TempData[WellKnownTempData.SuccessMessage] = "Rate settings updated";
@@ -140,50 +145,97 @@ public partial class UIStoresController
         });
     }
 
-    [HttpGet("{storeId}/rates/confirm")]
-    [Authorize(Policy = Policies.CanModifyStoreSettings, AuthenticationSchemes = AuthenticationSchemes.Cookie)]
-    public IActionResult ShowRateRules(bool scripting)
+    private void FillToStore(StoreBlob.RateSettings blob, RatesViewModel.Source model)
     {
-        return View("Confirm", new ConfirmModel
+        if (model.PreferredExchange != null)
+            model.PreferredExchange = model.PreferredExchange.Trim().ToLowerInvariant();
+        if (string.IsNullOrEmpty(model.PreferredExchange))
+            model.PreferredExchange = null;
+
+        blob.RateScripting = model.ShowScripting;
+        if (model.ShowScripting)
         {
-            Action = StringLocalizer["Continue"],
-            Title = StringLocalizer["Rate rule scripting"],
-            Description = scripting
-                ? StringLocalizer["This action will modify your current rate sources. Are you sure to turn on rate rules scripting? (Advanced users)"]
-                : StringLocalizer["This action will delete your rate script. Are you sure to turn off rate rules scripting?"],
-            ButtonClass = scripting ? "btn-primary" : "btn-danger"
-        });
+            RateRules? rules;
+            if (!RateRules.TryParse(model.Script, out rules, out var errors))
+            {
+                errors ??= [];
+                var errorString = string.Join(", ", errors.ToArray());
+                ModelState.AddModelError(nameof(model.Script), StringLocalizer["Parsing error: {0}", errorString]);
+                return;
+            }
+
+            blob.RateScript = rules.ToString();
+            ModelState.Remove(nameof(model.Script));
+        }
+        else
+        {
+            blob.RateScript = null;
+        }
+        blob.PreferredExchange = model.PreferredExchange;
+        if (model.PreferredExchange is not null && GetAvailableExchanges().All(a => a.Id != model.PreferredExchange))
+        {
+            ModelState.AddModelError(nameof(model.PreferredExchange), StringLocalizer["Unsupported exchange"]);
+            return;
+        }
     }
 
-    [HttpPost("{storeId}/rates/confirm")]
-    [Authorize(Policy = Policies.CanModifyStoreSettings, AuthenticationSchemes = AuthenticationSchemes.Cookie)]
-    public async Task<IActionResult> ShowRateRulesPost(bool scripting)
+    private void SetViewModel(RatesViewModel.Source vm, StoreBlob.RateSettings? rateSettings, StoreBlob storeBlob)
     {
-        var blob = CurrentStore.GetStoreBlob();
-        blob.RateScripting = scripting;
-        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 void FillFromStore(RatesViewModel vm, StoreBlob storeBlob)
-    {
-        var sources = _rateFactory.RateProviderFactory.AvailableRateProviders
-            .OrderBy(s => s.DisplayName, StringComparer.OrdinalIgnoreCase);
-        vm.AvailableExchanges = sources;
-        var exchange = storeBlob.GetPreferredExchange(_defaultRules);
+        if (rateSettings is null)
+            return;
+        var sources = GetAvailableExchanges();
+        var exchange = rateSettings.GetPreferredExchange(_defaultRules, storeBlob.DefaultCurrency);
         var chosenSource = sources.First(r => r.Id == exchange);
-        vm.Exchanges = _userStoresController.GetExchangesSelectList(storeBlob);
+        vm.Exchanges = _userStoresController.GetExchangesSelectList(storeBlob.DefaultCurrency, rateSettings);
         vm.PreferredExchange = vm.Exchanges.SelectedValue as string;
         vm.PreferredResolvedExchange = chosenSource.Id;
         vm.RateSource = chosenSource.Url;
+        vm.Script = rateSettings.GetRateRules(_defaultRules, storeBlob.Spread).ToString();
+        vm.DefaultScript = rateSettings.GetDefaultRateRules(_defaultRules, storeBlob.Spread).ToString();
+        vm.ShowScripting = rateSettings.RateScripting;
+
+        vm.ScriptingConfirm = new()
+        {
+            Title = StringLocalizer["Rate rule scripting"],
+            Action = StringLocalizer["Continue"],
+            GenerateForm = false
+        };
+        if (vm.ShowScripting)
+        {
+            vm.ScriptingConfirm.Description = StringLocalizer["This action will delete your rate script. Are you sure to turn off rate rules scripting?"];
+            vm.ScriptingConfirm.ButtonClass = "btn-danger";
+        }
+        else
+        {
+            vm.ScriptingConfirm.Description = StringLocalizer["This action will modify your current rate sources. Are you sure to turn on rate rules scripting? (Advanced users)"];
+            vm.ScriptingConfirm.ButtonClass = "btn-primary";
+        }
+    }
+
+    private List<RateSourceInfo> GetAvailableExchanges()
+    {
+        return _rateFactory.RateProviderFactory.AvailableRateProviders
+            .OrderBy(s => s.DisplayName, StringComparer.OrdinalIgnoreCase).ToList();
+    }
+
+    private void SetViewModel(RatesViewModel vm, StoreBlob storeBlob)
+    {
+        vm.AvailableExchanges = GetAvailableExchanges();
+        vm.PrimarySource = new();
+        vm.FallbackSource = new() { IsFallback = true };
+        SetViewModel(vm.PrimarySource, storeBlob.GetRateSettings(false), storeBlob);
+        if (storeBlob.GetRateSettings(true) is { } r)
+        {
+            vm.HasFallback = true;
+            SetViewModel(vm.FallbackSource, r, storeBlob);
+        }
+        else
+        {
+            SetViewModel(vm.FallbackSource, new(), storeBlob);
+        }
+
         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;
     }
 }