initial cart projection, cleaned up confirm process, cart services

src/Catalog/Catalog.Api/Registrations.cs

@@ -89,6 +89,8 @@ public static void AddEventuous(this IServiceCollection services, IConfiguration
                 .AddEventHandler<OfferStateProjection>()
                 .WithPartitioningByStream(2));
 
+        // TODO: add additional mongo, postgresql, and other custom projections
+
         // services.AddSubscription<AllStreamSubscription, AllStreamSubscriptionOptions>(
         //     "ProductDraftsProjections",
         //     builder => builder

src/Retail/ShoppingCart.Api/HttpApi/Carts/CartCommandApi.cs

@@ -39,14 +39,6 @@ public async Task<ActionResult<Result>> OpenCart([FromBody] CartCommands.V1.Remo
         return Ok(result);
     }
 
-    [HttpPost]
-    [Route("prepare-checkout")]
-    public async Task<ActionResult<Result>> PrepareForCheckout([FromBody] CartCommands.V1.ConfirmCartForCheckout cmd, CancellationToken ct)
-    {
-        var result = await _service.Handle(cmd, ct);
-        return Ok(result);
-    }
-
     [HttpPost]
     [Route("confirm")]
     public async Task<ActionResult<Result>> OpenCart([FromBody] CartCommands.V1.ConfirmCart cmd, CancellationToken ct)

src/Retail/ShoppingCart.Api/Infrastructure/Mongo.cs

@@ -0,0 +1,35 @@
+using MongoDb.Bson.NodaTime;
+using MongoDB.Driver;
+using MongoDB.Driver.Core.Extensions.DiagnosticSources;
+
+namespace ShoppingCart.Api.Infrastructure;
+
+public static class Mongo
+{
+    public static IMongoDatabase ConfigureMongo(IConfiguration configuration)
+    {
+        NodaTimeSerializers.Register();
+        var config = configuration.GetSection("Mongo").Get<MongoSettings>();
+
+        var settings = MongoClientSettings.FromConnectionString(config!.ConnectionString);
+
+        if (config.User != null && config.Password != null) {
+            settings.Credential = new MongoCredential(
+                null,
+                new MongoInternalIdentity("admin", config.User),
+                new PasswordEvidence(config.Password)
+            );
+        }
+
+        settings.ClusterConfigurator = cb => cb.Subscribe(new DiagnosticsActivityEventSubscriber());
+        return new MongoClient(settings).GetDatabase(config.Database);
+    }
+
+    public record MongoSettings
+    {
+        public string ConnectionString { get; init; } = null!;
+        public string Database { get; init; } = null!;
+        public string? User { get; init; }
+        public string? Password { get; init; }
+    }
+}

src/Retail/ShoppingCart.Api/Queries/Carts/UserCartDocument.cs

@@ -0,0 +1,13 @@
+using Eventuous.Projections.MongoDB.Tools;
+
+namespace ShoppingCart.Api.Queries.Carts;
+
+public record UserCartDocument : ProjectedDocument
+{
+    public UserCartDocument(string Id) : base(Id)
+    {
+    }
+
+    public string CustomerId { get; set; } = null!;
+    public string Status { get; set; } = null!;
+}

src/Retail/ShoppingCart.Api/Queries/Carts/UserCartProjection.cs

@@ -0,0 +1,38 @@
+using Eventuous.Projections.MongoDB;
+using Eventuous.Subscriptions.Context;
+using MongoDB.Driver;
+using ShoppingCart.Carts;
+
+namespace ShoppingCart.Api.Queries.Carts;
+
+[Obsolete("Obsolete per Eventuous; use new API instead (TODO)")]
+public class UserCartProjection : MongoProjection<UserCartDocument>
+{
+    public UserCartProjection(IMongoDatabase database) : base(database)
+    {
+        On<CartEvents.V1.CartOpened>(stream => stream.GetId(), Handle);
+
+        On<CartEvents.V1.CartConfirmed>(builder => builder
+            .UpdateOne
+            .DefaultId()
+            .Update((evt, update) =>
+                update.Set(x => x.Status, nameof(CartStatus.Confirmed))));
+
+        On<CartEvents.V1.CartCancelled>(builder => builder
+            .UpdateOne
+            .DefaultId()
+            .Update((evt, update) =>
+                update.Set(x => x.Status, nameof(CartStatus.Cancelled))));
+    }
+
+    private static UpdateDefinition<UserCartDocument> Handle(
+        IMessageConsumeContext<CartEvents.V1.CartOpened> ctx,
+        UpdateDefinitionBuilder<UserCartDocument> update)
+    {
+        var evt = ctx.Message;
+
+        return update.SetOnInsert(x => x.Id, ctx.Stream.GetId())
+            .Set(x => x.CustomerId, evt.CustomerId)
+            .Set(x => x.Status, nameof(CartStatus.Opened));
+    }
+}

src/Retail/ShoppingCart.Api/Registrations.cs

@@ -3,13 +3,19 @@
 using Eventuous;
 using Eventuous.Diagnostics.OpenTelemetry;
 using Eventuous.EventStore;
+using Eventuous.EventStore.Subscriptions;
+using Eventuous.Projections.MongoDB;
+using Eventuous.Subscriptions.Registrations;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
+using ShoppingCart.Api.Infrastructure;
+using ShoppingCart.Api.Queries.Carts;
 using ShoppingCart.Carts;
 using ShoppingCart.Inventories;
 using ShoppingCart.Prices;
+using ShoppingCart.Products;
 
 #pragma warning disable CS0618 // Type or member is obsolete
 
@@ -18,7 +24,6 @@ namespace ShoppingCart.Api;
 public static class Registrations
 {
     private const string OTelServiceName = "shoppingcart";
-    private const string PostgresSchemaName = "shoppingcart";
 
     public static void AddEventuous(this IServiceCollection services, IConfiguration configuration)
     {
@@ -37,8 +42,23 @@ public static void AddEventuous(this IServiceCollection services, IConfiguration
 
         // other internal and core services
         services.AddSingleton<ICombIdGenerator, CombIdGenerator>();
-        services.AddSingleton<ICheckInventoryService, CheckInventoryService>();
-        services.AddSingleton<IQuotePriceService, QuotePriceService>();
+        services.AddSingleton<IProductValidator, ProductValidator>();
+        services.AddSingleton<IInventoryChecker, InventoryChecker>();
+        services.AddSingleton<IPriceQuoter, PriceQuoter>();
+
+        // subscriptions: checkpoint stores
+        services.AddSingleton(Mongo.ConfigureMongo(configuration));
+        services.AddCheckpointStore<MongoCheckpointStore>();
+
+        // subscriptions: projections
+        services.AddSubscription<AllStreamSubscription, AllStreamSubscriptionOptions>(
+            "UserCartProjections",
+            builder => builder
+                .UseCheckpointStore<MongoCheckpointStore>()
+                .AddEventHandler<UserCartProjection>()
+                .WithPartitioningByStream(2));
+
+        // TODO: add additional mongo, postgresql, and other custom projections
 
         // health checks for subscription service
         services

src/Retail/ShoppingCart.Api/ShoppingCart.Api.csproj

@@ -9,9 +9,12 @@
         <PackageReference Include="Eventuous.Application" Version="$(EventuousVersion)" />
         <PackageReference Include="Eventuous.EventStore" Version="$(EventuousVersion)" />
         <PackageReference Include="Eventuous.Extensions.DependencyInjection" Version="$(EventuousVersion)" />
+        <PackageReference Include="Eventuous.Projections.MongoDB" Version="$(EventuousVersion)" />
         <PackageReference Include="Eventuous.AspNetCore.Web" Version="$(EventuousVersion)" />
         <PackageReference Include="Eventuous.Spyglass" Version="$(EventuousVersion)" />
         <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="8.0.6" />
+        <PackageReference Include="MongoDb.Bson.NodaTime" Version="3.0.0" />
+        <PackageReference Include="MongoDB.Driver.Core.Extensions.OpenTelemetry" Version="1.0.0" />
         <PackageReference Include="NodaTime.Serialization.SystemTextJson" Version="1.2.0" />
         <PackageReference Include="OpenTelemetry.Exporter.Prometheus.AspNetCore" Version="1.4.0-rc.4" />
         <PackageReference Include="OpenTelemetry.Exporter.Zipkin" Version="1.9.0" />

src/Retail/ShoppingCart.Api/appsettings.Development.json

@@ -11,5 +11,16 @@
     },
     "EventStore": {
         "ConnectionString": "esdb://localhost:2113?tls=false"
+    },
+    "Mongo": {
+        "ConnectionString": "mongodb://localhost:27017",
+        "User": "mongoadmin",
+        "Password": "secret",
+        "Database": "ShoppingCart"
+    },
+    "Postgres": {
+        "ConnectionString": "Server=127.0.0.1;Port=5432;Database=postgres;User Id=postgres;Password=Password123!;Include Error Detail=true;",
+        "Schema": "shopping_cart",
+        "InitializeDatabase": true
     }
 }

src/Retail/ShoppingCart/Carts/CartCommands.cs

@@ -20,11 +20,11 @@ public record RemoveProductFromCart(
             int Quantity
         );
 
-        public record ConfirmCartForCheckout(
+        public record ConfirmCart(
             string CartId
         );
 
-        public record ConfirmCart(
+        public record CancelCart(
             string CartId
         );
     }

src/Retail/ShoppingCart/Carts/CartEvents.cs

@@ -31,6 +31,11 @@ public record CartConfirmed(
             string CartId
         );
 
+        [EventType("V1.CartCancelled")]
+        public record CartCancelled(
+            string CartId
+        );
+
         [EventType("V1.EmptyCartDetected")]
         public record EmptyCartDetected(
             string CartId

src/Retail/ShoppingCart/Carts/CartFuncService.cs

@@ -24,8 +24,11 @@ public CartFuncService(
         OnExisting<Commands.RemoveProductFromCart>(cmd
             => GetStream(cmd.CartId), RemoveProductFromCart);
 
-        OnExisting<Commands.ConfirmCartForCheckout>(cmd
-            => GetStream(cmd.CartId), ConfirmCartForCheckout);
+        OnExisting<Commands.ConfirmCart>(cmd
+            => GetStream(cmd.CartId), ConfirmCart);
+
+        OnExisting<Commands.CancelCart>(cmd
+            => GetStream(cmd.CartId), CancelCart);
 
         static StreamName GetStream(string id) => new($"Cart-{id}");
 
@@ -66,13 +69,21 @@ static IEnumerable<object> RemoveProductFromCart(
                 yield return new Events.EmptyCartDetected(cmd.CartId);
         }
 
-        static IEnumerable<object> ConfirmCartForCheckout(
+        static IEnumerable<object> ConfirmCart(
             CartState state,
             object[] originalEvents,
-            Commands.ConfirmCartForCheckout cmd)
+            Commands.ConfirmCart cmd)
         {
             if (state.CanProceedToCheckout())
                 yield return new Events.CartConfirmed(cmd.CartId);
         }
+
+        static IEnumerable<object> CancelCart(
+            CartState state,
+            object[] originalEvents,
+            Commands.CancelCart cmd)
+        {
+            yield return new Events.CartCancelled(cmd.CartId);
+        }
     }
 }

src/Retail/ShoppingCart/Carts/CartState.cs

@@ -1,5 +1,6 @@
 using Ecommerce.Eventuous.Exceptions;
 using Eventuous;
+using ShoppingCart.Products;
 using static ShoppingCart.Carts.CartEvents.V1;
 
 namespace ShoppingCart.Carts;
@@ -19,6 +20,7 @@ public CartState()
         On<ProductAddedToCart>(Handle);
         On<ProductRemovedFromCart>(Handle);
         On<CartConfirmed>(Handle);
+        On<CartCancelled>(Handle);
     }
 
     private static CartState Handle(CartState state, CartOpened @event) => state with
@@ -37,19 +39,27 @@ private static CartState Handle(CartState state, CartOpened @event) => state wit
 
     private static CartState Handle(CartState state, ProductRemovedFromCart @event) => state.Status switch
     {
-        CartStatus.Confirmed => throw InvalidStateChangeException.For<CartState, ProductAddedToCart>(state.Id, CartStatus.Confirmed),
+        CartStatus.Confirmed => throw InvalidStateChangeException.For<CartState, ProductRemovedFromCart>(state.Id, CartStatus.Confirmed),
         _ => state with { ProductItems = state.ProductItems.Remove(ProductItem.From(@event.ProductId, @event.Quantity)) }
     };
 
     private static CartState Handle(CartState state, CartConfirmed @event) => state.Status switch
     {
-        CartStatus.Confirmed => throw InvalidStateChangeException.For<CartState, ProductAddedToCart>(state.Id, CartStatus.Confirmed),
+        CartStatus.Confirmed => throw InvalidStateChangeException.For<CartState, CartConfirmed>(state.Id, CartStatus.Confirmed),
         _ => state with { Status = CartStatus.Confirmed }
     };
 
+    private static CartState Handle(CartState state, CartCancelled @event) => state.Status switch
+    {
+        CartStatus.Confirmed => throw InvalidStateChangeException.For<CartState, CartCancelled>(state.Id, CartStatus.Confirmed),
+        CartStatus.Cancelled => throw InvalidStateChangeException.For<CartState, CartCancelled>(state.Id, CartStatus.Cancelled),
+        _ => state with { Status = CartStatus.Cancelled }
+    };
+
     public bool CanProceedToCheckout() => Status switch
     {
-        CartStatus.Unset or CartStatus.Opened => false,
+        CartStatus.Unset => false,
+        CartStatus.Confirmed => false,
         _ => HasProductItems
     };
 }

src/Retail/ShoppingCart/Carts/CartStatus.cs

@@ -4,5 +4,6 @@ public enum CartStatus
 {
     Unset = 0,
     Opened = 1,
-    Confirmed = 2
+    Confirmed = 2,
+    Cancelled = 4
 }

src/Retail/ShoppingCart/Inventories/ICheckInventoryService.cs → src/Retail/ShoppingCart/Inventories/IInventoryChecker.cs

@@ -1,8 +1,8 @@
-using ShoppingCart.Carts;
+using ShoppingCart.Products;
 
 namespace ShoppingCart.Inventories;
 
-public interface ICheckInventoryService
+public interface IInventoryChecker
 {
     IReadOnlyList<ProductItem> Check(params ProductId[] productIds);
 }

src/Retail/ShoppingCart/Inventories/CheckInventoryService.cs → src/Retail/ShoppingCart/Inventories/InventoryChecker.cs

@@ -1,8 +1,8 @@
-using ShoppingCart.Carts;
+using ShoppingCart.Products;
 
 namespace ShoppingCart.Inventories;
 
-public class CheckInventoryService : ICheckInventoryService
+public class InventoryChecker : IInventoryChecker
 {
     public IReadOnlyList<ProductItem> Check(params ProductId[] productIds)
     {

src/Retail/ShoppingCart/Prices/IQuotePriceService.cs → src/Retail/ShoppingCart/Prices/IPriceQuoter.cs

@@ -1,8 +1,8 @@
-using ShoppingCart.Carts;
+using ShoppingCart.Products;
 
 namespace ShoppingCart.Prices;
 
-public interface IQuotePriceService
+public interface IPriceQuoter
 {
     IReadOnlyList<PricedProductItem> Quote(params ProductItem[] productItems);
 }

src/Retail/ShoppingCart/Prices/QuotePriceService.cs → src/Retail/ShoppingCart/Prices/PriceQuoter.cs

@@ -1,8 +1,8 @@
-using ShoppingCart.Carts;
+using ShoppingCart.Products;
 
 namespace ShoppingCart.Prices;
 
-public class QuotePriceService : IQuotePriceService
+public class PriceQuoter : IPriceQuoter
 {
     public IReadOnlyList<PricedProductItem> Quote(params ProductItem[] productItems)
     {

src/Retail/ShoppingCart/Products/IProductValidator.cs

@@ -0,0 +1,6 @@
+namespace ShoppingCart.Products;
+
+public interface IProductValidator
+{
+    IReadOnlyList<(ProductId productId, bool isValid)> Quote(params ProductId[] productIds);
+}

src/Retail/ShoppingCart/Carts/PricedProductItem.cs → src/Retail/ShoppingCart/Products/PricedProductItem.cs

@@ -1,4 +1,4 @@
-namespace ShoppingCart.Carts;
+namespace ShoppingCart.Products;
 
 public class PricedProductItem
 {

src/Retail/ShoppingCart/Carts/ProductId.cs → src/Retail/ShoppingCart/Products/ProductId.cs

@@ -1,5 +1,5 @@
 using Eventuous;
 
-namespace ShoppingCart.Carts;
+namespace ShoppingCart.Products;
 
 public record ProductId(string Value) : Id(Value);

src/Retail/ShoppingCart/Carts/ProductItem.cs → src/Retail/ShoppingCart/Products/ProductItem.cs

@@ -1,4 +1,4 @@
-namespace ShoppingCart.Carts;
+namespace ShoppingCart.Products;
 
 public record ProductItem
 {