Add Domain project and shifted handlers to application.

wolverine/a-frame-architecture/FinancialApi.Application/TransferFundsHandler.cs

@@ -0,0 +1,60 @@
+using FinancialApi.Domain;
+using Wolverine.Attributes;
+using Wolverine.Persistence;
+
+namespace FinancialApi.Application;
+
+public interface IAccountQuery
+{
+    Task<Account?> FindByIdAsync(int id);
+}
+
+public record TransferFundsCommand(int SourceAccountId, int DestinationAccountId, decimal Amount);
+
+public record FundsTransferredEvent(int SourceAccountId, int DestinationAccountId, decimal Amount);
+
+public record TransferPair(Account Source, Account Destination);
+
+public static class TransferFundsHandler
+{
+    public static async Task<TransferPair?> LoadAsync(TransferFundsCommand cmd, IAccountQuery query)
+    {
+        var source = await query.FindByIdAsync(cmd.SourceAccountId);
+        var dest = await query.FindByIdAsync(cmd.DestinationAccountId);
+
+        if (source == null || dest == null) return null;
+
+        return new TransferPair(source, dest);
+    }
+
+    public static (
+        IStorageAction<Account> SourceWrite,
+        IStorageAction<Account> DestWrite,
+        IStorageAction<JournalEntry> JournalWrite,
+        FundsTransferredEvent Event
+        ) Handle(TransferFundsCommand cmd, TransferPair pair)
+    {
+        var updatedSource = pair.Source.Debit(cmd.Amount);
+        var updatedDest = pair.Destination.Credit(cmd.Amount);
+
+        var lines = new List<JournalLine>
+        {
+            new (pair.Source.Id, cmd.Amount, EntryType.Debit),
+            new (pair.Destination.Id, cmd.Amount, EntryType.Credit)
+        };
+
+        var journalEntry =
+            BalancedJournal.Create(Guid.NewGuid(),
+                $"Transfer: {cmd.Amount} from {cmd.SourceAccountId} to {cmd.DestinationAccountId}",
+                DateTimeOffset.UtcNow, lines);
+
+        var @event = new FundsTransferredEvent(cmd.SourceAccountId, cmd.DestinationAccountId, cmd.Amount);
+
+        return (
+            Storage.Update(updatedSource),
+            Storage.Update(updatedDest),
+            Storage.Insert(journalEntry.Entry),
+            @event
+        );
+    }
+}