Re-layout source code to correct namespaces (handlers, commands, etc.)

wolverine/a-frame-architecture/FinancialApi.Application/Handlers/ApplyFeeHandler.cs

@@ -0,0 +1,60 @@
+using FinancialApi.Application.Commands;
+using FinancialApi.Application.Events;
+using FinancialApi.Application.Queries;
+using FinancialApi.Domain;
+using Wolverine.Persistence;
+
+namespace FinancialApi.Application.Handlers;
+
+public static class ApplyFeeHandler
+{
+    public static async Task<FeePair> LoadAsync(
+        ApplyFeeCommand cmd,
+        IAccountQuery query, TimeProvider timeProvider)
+    {
+        var source = await query.FindByIdAsync(cmd.AccountId);
+        var dest = await query.FindByIdAsync(99999);
+        if (source == null || dest == null)
+        {
+            throw new InvalidOperationException($"Cannot process transfer. Account(s) not found.");
+        }
+
+        return new FeePair(source, dest, timeProvider.GetUtcNow());
+    }
+
+    public static (
+        IStorageAction<Account> CustomerWrite,
+        IStorageAction<Account> RevenueWrite,
+        IStorageAction<JournalEntry> JournalWrite,
+        FeeAppliedEvent Event
+        )
+        Handle(
+            ApplyFeeCommand cmd,
+            FeePair pair
+        )
+    {
+        var updatedSource = pair.Source.ApplyPosting(cmd.Amount, EntryType.Debit);
+        var updatedRevenue = pair.Destination.ApplyPosting(cmd.Amount, EntryType.Credit);
+        var serviceFee = 0.5m;
+        
+        var lines = new List<JournalLine>
+        {
+            new(updatedSource.Id, cmd.Amount, EntryType.Debit),
+            new(updatedRevenue.Id, cmd.Amount - serviceFee, EntryType.Credit),
+            new(updatedRevenue.Id, serviceFee, EntryType.Credit)
+        };
+        
+        var journalEntry = BalancedJournal.Create(Guid.NewGuid(),
+            $"Service Fee Applied: {cmd.Amount} to Account {cmd.AccountId}",
+            pair.TimeStamp, lines);
+
+        var @event = new FeeAppliedEvent(cmd.AccountId, cmd.Amount);
+
+        return (
+            Storage.Update(updatedSource),
+            Storage.Update(updatedRevenue),
+            Storage.Insert(journalEntry.Entry),
+            @event
+        );
+    }
+}

wolverine/a-frame-architecture/FinancialApi.Application/Handlers/FinancialEventHandler.cs

@@ -0,0 +1,39 @@
+using FinancialApi.Application.Events;
+using Microsoft.Extensions.Logging;
+
+namespace FinancialApi.Application.Handlers;
+
+public static class FinancialEventHandler
+{
+    public static void Handle(
+        FeeAppliedEvent @event,
+        IEventTracker store,
+        ILogger logger)
+    {
+        var message = $"FeeApplied: ${@event.Amount} moved from Account {@event.AccountId} to Account 99999.";
+        logger.LogInformation("BACKGROUND EVENT FIRED: {Message}", message);
+        store.Add(message);
+    }
+
+    public static void Handle(
+        FundsTransferredEvent @event,
+        IEventTracker store,
+        ILogger logger)
+    {
+        var message =
+            $"FundsTransferred: ${@event.Amount} moved from Account {@event.SourceAccountId} to Account {@event.DestinationAccountId}.";
+        logger.LogInformation("BACKGROUND EVENT FIRED: {Message}", message);
+        store.Add(message);
+    }
+
+    public static void Handle(
+        JournalReversedEvent @event,
+        IEventTracker store,
+        ILogger logger)
+    {
+        var message =
+            $"JournalReversed: Original Entry {@event.OriginalJournalId} was reversed by Entry {@event.ReversalJournalId}.";
+        logger.LogInformation("BACKGROUND EVENT FIRED: {Message}", message);
+        store.Add(message);
+    }
+}

wolverine/a-frame-architecture/FinancialApi.Application/Handlers/ReverseJournalHandler.cs

@@ -0,0 +1,50 @@
+using FinancialApi.Application.Commands;
+using FinancialApi.Application.Events;
+using FinancialApi.Application.Queries;
+using FinancialApi.Domain;
+using Wolverine.Persistence;
+
+namespace FinancialApi.Application.Handlers;
+
+public record ReversalData(
+    JournalEntry OriginalJournalEntry,
+    IReadOnlyList<Account> AffectedAccounts,
+    DateTimeOffset TimeStamp);
+
+public static class ReverseJournalHandler
+{
+    public static async Task<ReversalData?> LoadAsync(ReverseJournalCommand cmd, IReversalQuery query,
+        TimeProvider timeProvider)
+    {
+        var data = await query.GetReversalDataAsync(cmd.OriginalJournalId);
+        return data ?? throw new InvalidOperationException($"Journal Entry {cmd.OriginalJournalId} does not exist");
+    }
+
+    public static (
+        IStorageAction<JournalEntry> JournalWrite,
+        UnitOfWork<Account> AccountWrites,
+        JournalReversedEvent Event)
+        Handle(ReverseJournalCommand cmd, ReversalData data)
+    {
+        var reversalJournal =
+            BalancedJournal.CreateReversal(data.OriginalJournalEntry, $"Reversal: {cmd.Reason}", data.TimeStamp);
+        var accountState = data.AffectedAccounts.ToDictionary(a => a.Id);
+
+        reversalJournal.Entry.Lines.ForEach(l =>
+        {
+            var currentAccount = accountState[l.AccountId];
+            accountState[l.AccountId] = currentAccount.ApplyPosting(l.Amount, l.Type);
+        });
+        var accountUow = new UnitOfWork<Account>();
+        foreach (var account in accountState.Values)
+        {
+            accountUow.Update(account);
+        }
+
+        return (
+            Storage.Insert(reversalJournal.Entry),
+            accountUow,
+            new JournalReversedEvent(cmd.OriginalJournalId, reversalJournal.Entry.Id)
+        );
+    }
+}

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

@@ -0,0 +1,52 @@
+using FinancialApi.Application.Commands;
+using FinancialApi.Application.Events;
+using FinancialApi.Application.Queries;
+using FinancialApi.Domain;
+using Wolverine.Persistence;
+
+namespace FinancialApi.Application.Handlers;
+
+public static class TransferFundsHandler
+{
+    public static async Task<TransferPair?> LoadAsync(TransferFundsCommand cmd, IAccountQuery query,
+        TimeProvider timeProvider)
+    {
+        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, timeProvider.GetUtcNow());
+    }
+
+    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}",
+                pair.TimeStamp, lines);
+
+        var @event = new FundsTransferredEvent(cmd.SourceAccountId, cmd.DestinationAccountId, cmd.Amount);
+
+        return (
+            Storage.Update(updatedSource),
+            Storage.Update(updatedDest),
+            Storage.Insert(journalEntry.Entry),
+            @event
+        );
+    }
+}