refactor(app): implement year filter for account entries and update related services

src/Duempelkas.Infrastructure/Services/BalanceQueryService.cs

@@ -12,7 +12,7 @@ public class BalanceQueryService : IBalanceQueryService
 
     public BalanceQueryService(IDbContextFactory<FinanceDbContext> dbFactory) => _dbFactory = dbFactory;
 
-    public async Task<AccountBalanceDto> GetAccountBalanceAsync(int accountId)
+    public async Task<AccountBalanceDto> GetAccountBalanceAsync(int accountId, int? year = null)
     {
         await using var db = await _dbFactory.CreateDbContextAsync();
 
@@ -21,21 +21,33 @@ public class BalanceQueryService : IBalanceQueryService
             .FirstOrDefaultAsync(a => a.Id == accountId)
             ?? throw new InvalidOperationException($"Konto {accountId} nicht gefunden.");
 
-        var currentYear = DateTime.Now.Year;
+        var selectedYear = year ?? DateTime.Now.Year;
 
         var activeEntries = account.Entries.Where(e => !e.IsDeleted).ToList();
         var totalIncome = activeEntries.Where(e => e.Type == EntryType.Income).Sum(e => e.Amount);
         var totalExpense = activeEntries.Where(e => e.Type == EntryType.Expense).Sum(e => e.Amount);
-        var currentYearIncome = activeEntries.Where(e => e.Type == EntryType.Income && e.Date.Year == currentYear).Sum(e => e.Amount);
-        var currentYearExpense = activeEntries.Where(e => e.Type == EntryType.Expense && e.Date.Year == currentYear).Sum(e => e.Amount);
-        var totalBalance = account.CarryoverBalance + totalIncome - totalExpense;
+
+        var selectedYearIncome = activeEntries
+            .Where(e => e.Type == EntryType.Income && e.Date.Year == selectedYear)
+            .Sum(e => e.Amount);
+        var selectedYearExpense = activeEntries
+            .Where(e => e.Type == EntryType.Expense && e.Date.Year == selectedYear)
+            .Sum(e => e.Amount);
+
+        var selectedYearCarryover = account.CarryoverBalance + activeEntries
+            .Where(e => e.Date.Year < selectedYear)
+            .Sum(e => e.Type == EntryType.Income ? e.Amount : -e.Amount);
+
+        var totalBalance = year.HasValue
+            ? selectedYearCarryover + selectedYearIncome - selectedYearExpense
+            : account.CarryoverBalance + totalIncome - totalExpense;
 
         return new AccountBalanceDto(
-            account.CarryoverBalance,
+            year.HasValue ? selectedYearCarryover : account.CarryoverBalance,
             totalIncome,
             totalExpense,
-            currentYearIncome,
-            currentYearExpense,
+            selectedYearIncome,
+            selectedYearExpense,
             totalBalance);
     }
 }