Add an option to resolve store when handling a command (#216)

* Add an option to resolve store when handling a command
* New command/func service API

.github/workflows/code_quality.yml

@@ -14,6 +14,8 @@ jobs:
         with:
           fetch-depth: 0
       - name: 'Qodana Scan'
-        uses: JetBrains/qodana-action@v2022.3.3
+        uses: JetBrains/qodana-action@v2023.2.1
+        with:
+          pr-mode: false
         env:
           QODANA_TOKEN: ${{ secrets.QODANA_TOKEN }}

Directory.Packages.props

@@ -42,8 +42,8 @@
     <PackageVersion Include="RabbitMQ.Client" Version="6.5.0" />
     <PackageVersion Include="Microsoft.Data.SqlClient" Version="5.1.1" />
     <PackageVersion Include="NEST" Version="7.17.5" />
-    <PackageVersion Include="Polly" Version="7.2.3" />
-    <PackageVersion Include="Newtonsoft.Json" Version="13.0.1" />
+    <PackageVersion Include="Polly" Version="7.2.4" />
+    <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="StackExchange.Redis" Version="2.6.90" />
     <PackageVersion Include="Testcontainers.EventStoreDb" Version="3.4.0" />
     <PackageVersion Include="Testcontainers.Kafka" Version="3.4.0" />
@@ -55,7 +55,7 @@
   </ItemGroup>
   <ItemGroup Label="References for packable projects">
     <PackageVersion Include="MinVer" Version="4.3.0" PrivateAssets="All" />
-    <PackageVersion Include="JetBrains.Annotations" Version="2022.3.1" PrivateAssets="All" />
+    <PackageVersion Include="JetBrains.Annotations" Version="2023.2.0" PrivateAssets="All" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All" />
   </ItemGroup>
   <ItemGroup Label="References for test projects">
@@ -73,7 +73,7 @@
     <PackageVersion Include="RestSharp" Version="110.2.0" />
     <PackageVersion Include="Hypothesist" Version="2.1.55" />
     <PackageVersion Include="NodaTime" Version="3.1.9" />
-    <PackageVersion Include="NodaTime.Serialization.SystemTextJson" Version="1.0.0" />
+    <PackageVersion Include="NodaTime.Serialization.SystemTextJson" Version="1.1.0" />
     <PackageVersion Include="MicroElements.AutoFixture.NodaTime" Version="1.0.0" />
     <PackageVersion Include="MongoDb.Bson.NodaTime" Version="3.0.0" />
     <PackageVersion Include="Testcontainers" Version="3.4.0" />

src/Benchmarks/Benchmarks/GapDetectionBenchmarks.cs

@@ -19,7 +19,7 @@ public class GapDetectionBenchmarks {
     public void Setup() {
         _store = new NoOpCheckpointStore();
 
-        _store.CheckpointStored += (sender, checkpoint) => Console.WriteLine(checkpoint);
+        _store.CheckpointStored += (_, checkpoint) => Console.WriteLine(checkpoint);
 
         var numbers = Enumerable.Range(1, 1000).ToList();
         numbers.RemoveAll(x => x % 10 == 0);

src/Benchmarks/Benchmarks/TypeMapBenchmark.cs

@@ -12,6 +12,7 @@ public class TypeMapBenchmark {
     KeyValuePair<string, Type>[] _types = null!;
 
     [Params(5, 20, 100)]
+    // ReSharper disable once UnusedAutoPropertyAccessor.Global
     public int TypesCount { get; set; }
 
     [GlobalSetup]

src/Core/src/Eventuous.Application/AggregateService/CommandHandlerBuilder.cs

@@ -0,0 +1,113 @@
+// Copyright (C) Ubiquitous AS.All rights reserved
+// Licensed under the Apache License, Version 2.0.
+
+namespace Eventuous;
+
+public abstract class CommandHandlerBuilder<TAggregate, TState, TId>
+    where TAggregate : Aggregate<TState> where TId : Id where TState : State<TState>, new() {
+    internal abstract RegisteredHandler<TAggregate, TId> Build();
+}
+
+/// <summary>
+/// Builds a command handler for a specific command type. You would not need to instantiate this class directly,
+/// use <see cref="CommandService{TAggregate,TState,TId}.On{TCommand}" /> function.
+/// </summary>
+/// <param name="store">Default aggregate store instance for the command service</param>
+/// <typeparam name="TCommand">Command type</typeparam>
+/// <typeparam name="TAggregate">Aggregate type</typeparam>
+/// <typeparam name="TState">State of the aggregate type</typeparam>
+/// <typeparam name="TId">Identity of the aggregate type</typeparam>
+public class CommandHandlerBuilder<TCommand, TAggregate, TState, TId>(IAggregateStore? store) : CommandHandlerBuilder<TAggregate, TState, TId>
+    where TCommand : class
+    where TAggregate : Aggregate<TState>, new()
+    where TState : State<TState>, new()
+    where TId : Id {
+    GetIdFromUntypedCommand<TId>?     _getId;
+    HandleUntypedCommand<TAggregate>? _action;
+    ResolveStore<TCommand>?           _resolveStore;
+    ExpectedState                     _expectedState = ExpectedState.Any;
+
+    /// <summary>
+    /// Set the expected aggregate state for the command handler.
+    /// If the aggregate won't be in the expected state, the command handler will return an error.
+    /// The default is <see cref="ExpectedState.Any" />.
+    /// </summary>
+    /// <param name="expectedState">Expected aggregate state</param>
+    /// <returns></returns>
+    public CommandHandlerBuilder<TCommand, TAggregate, TState, TId> InState(ExpectedState expectedState) {
+        _expectedState = expectedState;
+
+        return this;
+    }
+
+    /// <summary>
+    /// Defines how the aggregate id is extracted from the command.
+    /// </summary>
+    /// <param name="getId">A function to get the aggregate id from the command.</param>
+    /// <returns></returns>
+    public CommandHandlerBuilder<TCommand, TAggregate, TState, TId> GetId(GetIdFromCommand<TId, TCommand> getId) {
+        _getId = getId.AsGetId();
+
+        return this;
+    }
+
+    /// <summary>
+    /// Defines how the aggregate id is extracted from the command, asynchronously.
+    /// </summary>
+    /// <param name="getId">A function to get the aggregate id from the command.</param>
+    /// <returns></returns>
+    public CommandHandlerBuilder<TCommand, TAggregate, TState, TId> GetIdAsync(GetIdFromCommandAsync<TId, TCommand> getId) {
+        _getId = getId.AsGetId();
+
+        return this;
+    }
+
+    /// <summary>
+    /// Defines how the aggregate is acted upon by the command.
+    /// </summary>
+    /// <param name="action">A function that executes an operation on an aggregate</param>
+    /// <returns></returns>
+    public CommandHandlerBuilder<TCommand, TAggregate, TState, TId> Act(ActOnAggregate<TAggregate, TCommand> action) {
+        _action = action.AsAct();
+
+        return this;
+    }
+
+    /// <summary>
+    /// Defines how the aggregate is acted upon by the command, asynchronously.
+    /// </summary>
+    /// <param name="action">A function that executes an asynchronous operation on an aggregate</param>
+    /// <returns></returns>
+    public CommandHandlerBuilder<TCommand, TAggregate, TState, TId> ActAsync(ActOnAggregateAsync<TAggregate, TCommand> action) {
+        _action = action.AsAct();
+
+        return this;
+    }
+
+    /// <summary>
+    /// Defines how the aggregate store is resolved from the command. It is optional. If not defined, the default
+    /// aggregate store of the command service will be used.
+    /// </summary>
+    /// <param name="resolveStore"></param>
+    /// <returns></returns>
+    public CommandHandlerBuilder<TCommand, TAggregate, TState, TId> ResolveStore(ResolveStore<TCommand>? resolveStore) {
+        _resolveStore = resolveStore;
+
+        return this;
+    }
+
+    internal override RegisteredHandler<TAggregate, TId> Build() {
+        return new RegisteredHandler<TAggregate, TId>(
+            _expectedState,
+            Ensure.NotNull(_getId, $"Function to get the aggregate id from {typeof(TCommand).Name} is not defined"),
+            Ensure.NotNull(_action, $"Function to act on the aggregate for command {typeof(TCommand).Name} is not defined"),
+            (_resolveStore ?? DefaultResolve()).AsResolveStore()
+        );
+    }
+
+    ResolveStore<TCommand> DefaultResolve() {
+        ArgumentNullException.ThrowIfNull(store, nameof(store));
+
+        return _ => store;
+    }
+}

src/Core/src/Eventuous.Application/AggregateService/CommandHandlersMap.cs

@@ -0,0 +1,55 @@
+// Copyright (C) Ubiquitous AS. All rights reserved
+// Licensed under the Apache License, Version 2.0.
+
+using System.Reflection;
+
+namespace Eventuous;
+
+using static Diagnostics.ApplicationEventSource;
+
+public delegate Task ActOnAggregateAsync<in TAggregate, in TCommand>(TAggregate aggregate, TCommand command, CancellationToken cancellationToken)
+    where TAggregate : Aggregate;
+
+public delegate void ActOnAggregate<in TAggregate, in TCommand>(TAggregate aggregate, TCommand command) where TAggregate : Aggregate;
+
+delegate ValueTask<T> HandleUntypedCommand<T>(T aggregate, object command, CancellationToken cancellationToken) where T : Aggregate;
+
+public delegate Task<TId> GetIdFromCommandAsync<TId, in TCommand>(TCommand command, CancellationToken cancellationToken) where TId : Id where TCommand : class;
+
+public delegate TId GetIdFromCommand<out TId, in TCommand>(TCommand command) where TId : Id where TCommand : class;
+
+delegate ValueTask<TId> GetIdFromUntypedCommand<TId>(object command, CancellationToken cancellationToken) where TId : Id;
+
+public delegate IAggregateStore ResolveStore<in TCommand>(TCommand command) where TCommand : class;
+
+delegate IAggregateStore ResolveStoreFromCommand(object command);
+
+record RegisteredHandler<T, TId>(
+        ExpectedState                ExpectedState,
+        GetIdFromUntypedCommand<TId> GetId,
+        HandleUntypedCommand<T>      Handler,
+        ResolveStoreFromCommand      ResolveStore
+    ) where T : Aggregate where TId : Id;
+
+class HandlersMap<TAggregate, TId> where TAggregate : Aggregate where TId : Id {
+    readonly TypeMap<RegisteredHandler<TAggregate, TId>> _typeMap = new();
+
+    static readonly MethodInfo AddHandlerInternalMethod =
+        typeof(HandlersMap<TAggregate, TId>).GetMethod(nameof(AddHandlerInternal), BindingFlags.NonPublic | BindingFlags.Instance)!;
+
+    internal void AddHandlerInternal<TCommand>(RegisteredHandler<TAggregate, TId> handler) {
+        try {
+            _typeMap.Add<TCommand>(handler);
+            Log.CommandHandlerRegistered<TCommand>();
+        } catch (Exceptions.DuplicateTypeException<TCommand>) {
+            Log.CommandHandlerAlreadyRegistered<TCommand>();
+
+            throw new Exceptions.CommandHandlerAlreadyRegistered<TCommand>();
+        }
+    }
+
+    internal void AddHandlerUntyped(Type command, RegisteredHandler<TAggregate, TId> handler)
+        => AddHandlerInternalMethod.MakeGenericMethod(command).Invoke(this, new object?[] { handler });
+
+    public bool TryGet<TCommand>([NotNullWhen(true)] out RegisteredHandler<TAggregate, TId>? handler) => _typeMap.TryGetValue<TCommand>(out handler);
+}

src/Core/src/Eventuous.Application/AggregateService/CommandHandlingDelegateExtensions.cs

@@ -0,0 +1,29 @@
+// Copyright (C) Ubiquitous AS.All rights reserved
+// Licensed under the Apache License, Version 2.0.
+
+namespace Eventuous;
+
+static class CommandHandlingDelegateExtensions {
+    public static GetIdFromUntypedCommand<TId> AsGetId<TId, TCommand>(this GetIdFromCommandAsync<TId, TCommand> getId) where TId : Id where TCommand : class
+        => async (cmd, ct) => await getId((TCommand)cmd, ct);
+
+    public static GetIdFromUntypedCommand<TId> AsGetId<TId, TCommand>(this GetIdFromCommand<TId, TCommand> getId) where TId : Id where TCommand : class
+        => (cmd, _) => ValueTask.FromResult(getId((TCommand)cmd));
+
+    public static HandleUntypedCommand<TAggregate> AsAct<TAggregate, TCommand>(this ActOnAggregateAsync<TAggregate, TCommand> act) where TAggregate : Aggregate
+        => async (aggregate, cmd, ct) => {
+            await act(aggregate, (TCommand)cmd, ct).NoContext();
+
+            return aggregate;
+        };
+
+    public static HandleUntypedCommand<TAggregate> AsAct<TAggregate, TCommand>(this ActOnAggregate<TAggregate, TCommand> act) where TAggregate : Aggregate
+        => (aggregate, cmd, _) => {
+            act(aggregate, (TCommand)cmd);
+
+            return ValueTask.FromResult(aggregate);
+        };
+
+    public static ResolveStoreFromCommand AsResolveStore<TCommand>(this ResolveStore<TCommand> resolveStore) where TCommand : class
+        => cmd => resolveStore((TCommand)cmd);
+}

src/Core/src/Eventuous.Application/AggregateService/CommandService.Async.cs

@@ -0,0 +1,88 @@
+// Copyright (C) Ubiquitous AS. All rights reserved
+// Licensed under the Apache License, Version 2.0.
+
+namespace Eventuous;
+
+public abstract partial class CommandService<TAggregate, TState, TId> {
+    /// <summary>
+    /// Register an asynchronous handler for a command, which is expected to create a new aggregate instance.
+    /// </summary>
+    /// <param name="getId">A function to get the aggregate id from the command</param>
+    /// <param name="action">Asynchronous action to be performed on the aggregate, given the aggregate instance and the command</param>
+    /// <param name="resolveStore">Resolve aggregate store from the command</param>
+    /// <typeparam name="TCommand">Command type</typeparam>
+    [Obsolete("Use On<TCommand>().InState(ExpectedState.New).GetId(...).ActAsync(...).ResolveStore(...) instead")]
+    protected void OnNewAsync<TCommand>(
+            GetIdFromCommand<TId, TCommand>           getId,
+            ActOnAggregateAsync<TAggregate, TCommand> action,
+            ResolveStore<TCommand>?                   resolveStore = null
+        ) where TCommand : class
+        => On<TCommand>().InState(ExpectedState.New).GetId(getId).ActAsync(action).ResolveStore(resolveStore);
+
+    /// <summary>
+    /// Register an asynchronous handler for a command, which is expected to use an existing aggregate instance.
+    /// </summary>
+    /// <param name="getId">A function to get the aggregate id from the command</param>
+    /// <param name="action">Asynchronous action to be performed on the aggregate, given the aggregate instance and the command</param>
+    /// <param name="resolveStore">Resolve aggregate store from the command</param>
+    /// <typeparam name="TCommand">Command type</typeparam>
+    [Obsolete("Use On<TCommand>().InState(ExpectedState.Existing).GetId(...).ActAsync(...).ResolveStore(...) instead")]
+    [PublicAPI]
+    protected void OnExistingAsync<TCommand>(
+            GetIdFromCommand<TId, TCommand>           getId,
+            ActOnAggregateAsync<TAggregate, TCommand> action,
+            ResolveStore<TCommand>?                   resolveStore = null
+        ) where TCommand : class
+        => On<TCommand>().InState(ExpectedState.Existing).GetId(getId).ActAsync(action).ResolveStore(resolveStore);
+
+    /// <summary>
+    /// Register an asynchronous handler for a command, which is expected to use an existing aggregate instance.
+    /// </summary>
+    /// <param name="getId">Asynchronous function to get the aggregate id from the command</param>
+    /// <param name="action">Asynchronous action to be performed on the aggregate, given the aggregate instance and the command</param>
+    /// <param name="resolveStore">Resolve aggregate store from the command</param>
+    /// <typeparam name="TCommand">Command type</typeparam>
+    [Obsolete("Use On<TCommand>().InState(ExpectedState.Existing).GetIdAsync(...).ActAsync(...).ResolveStore(...) instead")]
+    [PublicAPI]
+    protected void OnExistingAsync<TCommand>(
+            GetIdFromCommandAsync<TId, TCommand>      getId,
+            ActOnAggregateAsync<TAggregate, TCommand> action,
+            ResolveStore<TCommand>?                   resolveStore = null
+        ) where TCommand : class
+    // => _handlers.AddHandler(ExpectedState.Existing, getId, action, resolveStore ?? DefaultResolve<TCommand>());
+        => On<TCommand>().InState(ExpectedState.Existing).GetIdAsync(getId).ActAsync(action).ResolveStore(resolveStore);
+
+    /// <summary>
+    /// Register an asynchronous handler for a command, which is expected to use an a new or an existing aggregate instance.
+    /// </summary>
+    /// <param name="getId">A function to get the aggregate id from the command</param>
+    /// <param name="action">Asynchronous action to be performed on the aggregate, given the aggregate instance and the command</param>
+    /// <param name="resolveStore">Resolve aggregate store from the command</param>
+    /// <typeparam name="TCommand">Command type</typeparam>
+    [Obsolete("Use On<TCommand>().InState(ExpectedState.Any).GetId(...).ActAsync(...).ResolveStore(...) instead")]
+    [PublicAPI]
+    protected void OnAnyAsync<TCommand>(
+            GetIdFromCommand<TId, TCommand>           getId,
+            ActOnAggregateAsync<TAggregate, TCommand> action,
+            ResolveStore<TCommand>?                   resolveStore = null
+        ) where TCommand : class
+        // => _handlers.AddHandler(ExpectedState.Any, getId, action, resolveStore ?? DefaultResolve<TCommand>());
+        => On<TCommand>().InState(ExpectedState.Any).GetId(getId).ActAsync(action).ResolveStore(resolveStore);
+
+    /// <summary>
+    /// Register an asynchronous handler for a command, which is expected to use an a new or an existing aggregate instance.
+    /// </summary>
+    /// <param name="getId">Asynchronous function to get the aggregate id from the command</param>
+    /// <param name="action">Asynchronous action to be performed on the aggregate, given the aggregate instance and the command</param>
+    /// <param name="resolveStore">Resolve aggregate store from the command</param>
+    /// <typeparam name="TCommand">Command type</typeparam>
+    [Obsolete("Use On<TCommand>().InState(ExpectedState.Any).GetIdAsync(...).ActAsync(...).ResolveStore(...) instead")]
+    [PublicAPI]
+    protected void OnAnyAsync<TCommand>(
+            GetIdFromCommandAsync<TId, TCommand>      getId,
+            ActOnAggregateAsync<TAggregate, TCommand> action,
+            ResolveStore<TCommand>?                   resolveStore = null
+        ) where TCommand : class
+        // => _handlers.AddHandler(ExpectedState.Any, getId, action, resolveStore ?? DefaultResolve<TCommand>());
+        => On<TCommand>().InState(ExpectedState.Any).GetIdAsync(getId).ActAsync(action).ResolveStore(resolveStore);
+}