Fix SpendingsOverTime chart: apply FX conversion and use subclass names

ChartService summed raw transaction Value instead of converting via
GetValue(account.IsFxAccount), so FX expense accounts charted in their
foreign currency labeled as CHF. Subclass series also took their Name
from an arbitrary account in the group instead of the actual subclass
name.

Schaad.Accounting.Services/ChartService.cs

@@ -31,28 +31,32 @@ namespace Schaad.Accounting.Services
                 .Count();
 
             return distinctSubClasses > 1
-                ? GetSubClassExpensesPerMonth(expenseTransactions)
+                ? await GetSubClassExpensesPerMonthAsync(expenseTransactions)
                 : await GetAccountExpensesPerMonthAsync();
         }
 
-        private List<DataSerie> GetSubClassExpensesPerMonth(List<TransactionDataset> expenseTransactions)
+        private async Task<List<DataSerie>> GetSubClassExpensesPerMonthAsync(List<TransactionDataset> expenseTransactions)
         {
             var year = settingsService.GetYear();
             var maxMonth = expenseTransactions
                 .OrderByDescending(t => t.ValueDate)
                 .FirstOrDefault()?.ValueDate.Month ?? 12;
 
+            var subClassNameByNumber = (await viewService.GetAccountViewListAsync())
+                .GroupBy(a => a.SubClass)
+                .ToDictionary(g => g.Key, g => g.First().SubClassName);
+
             var list = new List<DataSerie>();
             foreach (var grp in expenseTransactions.GroupBy(t => t.TargetAccount.SubClass))
             {
                 var groupedByMonth = grp
                     .GroupBy(t => t.ValueDate.Month)
-                    .ToDictionary(g => g.Key, g => g.Sum(t => t.Value));
+                    .ToDictionary(g => g.Key, g => g.Sum(t => t.GetValue(t.TargetAccount.IsFxAccount)));
                 EnsureEntryForEveryMonth(groupedByMonth, maxMonth);
 
                 list.Add(new DataSerie(
                     Id: grp.Key.ToString(),
-                    Name: grp.First().TargetAccount.Name,
+                    Name: subClassNameByNumber[grp.Key],
                     X: groupedByMonth.OrderBy(g => g.Key).Select(g => new DateOnly(year, g.Key, 1)).ToList(),
                     Y: groupedByMonth.OrderBy(g => g.Key).Select(g => g.Value).ToList()
                 ));
@@ -78,7 +82,7 @@ namespace Schaad.Accounting.Services
                 var maxMonth = transactions.Max(t => t.ValueDate.Month);
                 var groupedByMonth = transactions
                     .GroupBy(t => t.ValueDate.Month)
-                    .ToDictionary(g => g.Key, g => g.Sum(t => t.Value));
+                    .ToDictionary(g => g.Key, g => g.Sum(t => t.GetValue(account.IsFxAccount)));
                 EnsureEntryForEveryMonth(groupedByMonth, maxMonth);
 
                 list.Add(new DataSerie(

Schaad.Accounting.Tests/ChartServiceTestShould.cs

@@ -1,3 +1,4 @@
+using System.Linq;
 using NSubstitute;
 using Schaad.Accounting.Datasets;
 using Schaad.Accounting.Interfaces;
@@ -70,7 +71,7 @@ public class ChartServiceTestShould
         var checking = MakeAccount("chk", 1010);
         viewService.GetAccountViewListAsync().Returns(new List<AccountDataset>
         {
-            AsDataset(groceries), AsDataset(utilities), AsDataset(checking)
+            AsDataset(groceries, subClassName: "Groceries"), AsDataset(utilities, subClassName: "Utilities"), AsDataset(checking)
         });
         viewService.GetTransactionViewListAsync().Returns(new List<TransactionDataset>
         {
@@ -81,8 +82,8 @@ public class ChartServiceTestShould
         var series = await BuildService().GetExpensesPerMonthAsync();
 
         series.Count.ShouldBe(2);
-        series.ShouldContain(s => s.Id == "42");
+        series.ShouldContain(s => s.Id == "42" && s.Name == "Groceries");
-        series.ShouldContain(s => s.Id == "43");
+        series.ShouldContain(s => s.Id == "43" && s.Name == "Utilities");
     }
 
     [Fact]
@@ -106,18 +107,18 @@ public class ChartServiceTestShould
         series[0].Id.ShouldBe("groc");
     }
 
-    private static Account MakeAccount(string id, int number) => new()
+    private static Account MakeAccount(string id, int number, string currency = "CHF") => new()
     {
         Id = id,
         Number = number,
         Name = id,
-        Currency = "CHF"
+        Currency = currency
     };
 
-    private static AccountDataset AsDataset(Account a) =>
+    private static AccountDataset AsDataset(Account a, string subClassName = "") =>
-        new(a, balance: 0, balanceCHF: 0, startBalanceCHF: 0, className: "", subClassName: "");
+        new(a, balance: 0, balanceCHF: 0, startBalanceCHF: 0, className: "", subClassName: subClassName);
 
-    private static TransactionDataset MakeTransaction(Account origin, Account target, decimal value, DateTime valueDate) =>
+    private static TransactionDataset MakeTransaction(Account origin, Account target, decimal value, DateTime valueDate, decimal? fxRate = null) =>
         new(
             new Transaction
             {
@@ -125,8 +126,46 @@ public class ChartServiceTestShould
                 OriginAccountId = origin.Id,
                 TargetAccountId = target.Id,
                 Value = value,
+                FxRate = fxRate,
                 ValueDate = valueDate,
                 BookingDate = valueDate
             },
             origin, target);
+
+    [Fact]
+    public async Task ConvertFxAccountValuesWhenBuildingAccountSeries()
+    {
+        var usSubscription = MakeAccount("us", 4000, currency: "USD");
+        var checking = MakeAccount("chk", 1010);
+        viewService.GetAccountViewListAsync().Returns(new List<AccountDataset> { AsDataset(usSubscription), AsDataset(checking) });
+        viewService.GetTransactionViewListAsync().Returns(new List<TransactionDataset>
+        {
+            MakeTransaction(checking, usSubscription, value: 100m, valueDate: new DateTime(2026, 1, 1), fxRate: 0.5m)
+        });
+
+        var series = await BuildService().GetExpensesPerMonthAsync();
+
+        series.Single().Y.Single().ShouldBe(200m);
+    }
+
+    [Fact]
+    public async Task ConvertFxAccountValuesWhenBuildingSubClassSeries()
+    {
+        var usSubscription = MakeAccount("us", 4200, currency: "USD");
+        var utilities = MakeAccount("util", 4300);
+        var checking = MakeAccount("chk", 1010);
+        viewService.GetAccountViewListAsync().Returns(new List<AccountDataset>
+        {
+            AsDataset(usSubscription), AsDataset(utilities), AsDataset(checking)
+        });
+        viewService.GetTransactionViewListAsync().Returns(new List<TransactionDataset>
+        {
+            MakeTransaction(checking, usSubscription, value: 100m, valueDate: new DateTime(2026, 1, 1), fxRate: 0.5m),
+            MakeTransaction(checking, utilities, value: 30m, valueDate: new DateTime(2026, 2, 1))
+        });
+
+        var series = await BuildService().GetExpensesPerMonthAsync();
+
+        series.Single(s => s.Id == "42").Y[0].ShouldBe(200m);
+    }
 }