Add event bus events for catalog service. (#8)

* Add event bus events for catalog service.

* Fix logic for catalog publishing events.

src/Services/Catalog/Catalog.API/Controllers/CatalogController.cs

@@ -216,13 +216,19 @@ public class CatalogController : ControllerBase
         }
 
         var oldPrice = catalogItem.Price;
+        var oldStock = catalogItem.AvailableStock;
         var raiseProductPriceChangedEvent = oldPrice != productToUpdate.Price;
+        var raiseProductStockChangedEvent = oldStock != productToUpdate.AvailableStock;
 
         // Update current product
         catalogItem = productToUpdate;
         _catalogContext.CatalogItems.Update(catalogItem);
 
-        if (raiseProductPriceChangedEvent) // Save product's data and publish integration event through the Event Bus if price has changed
+        if (!raiseProductPriceChangedEvent && !raiseProductStockChangedEvent)// Just save the updated product because the Product's Price hasn't changed.
+        {
+            await _catalogContext.SaveChangesAsync();
+        }
+        else if (raiseProductPriceChangedEvent) // Save product's data and publish integration event through the Event Bus if price has changed
         {
             //Create Integration Event to be published through the Event Bus
             var priceChangedEvent = new ProductPriceChangedIntegrationEvent(catalogItem.Id, productToUpdate.Price, oldPrice);
@@ -233,10 +239,19 @@ public class CatalogController : ControllerBase
             // Publish through the Event Bus and mark the saved event as published
             await _catalogIntegrationEventService.PublishThroughEventBusAsync(priceChangedEvent);
         }
-        else // Just save the updated product because the Product's Price hasn't changed.
+        else if (raiseProductStockChangedEvent)
         {
-            await _catalogContext.SaveChangesAsync();
+            // Create Integration Event to be published through the Event Bus
+            var stockChangedEvent = new ProductStockChangedIntegrationEvent(catalogItem.Id, productToUpdate.AvailableStock, oldStock);
+
+            // Achieving atomicity between original Catalog database operation and the IntegrationEventLog thanks to a local transaction
+            await _catalogIntegrationEventService.SaveEventAndCatalogContextChangesAsync(stockChangedEvent);
+
+            // Publish through the Event Bus and mark the saved event as published
+            await _catalogIntegrationEventService.PublishThroughEventBusAsync(stockChangedEvent);
+
         }
+      
 
         return CreatedAtAction(nameof(ItemByIdAsync), new { id = productToUpdate.Id }, null);
     }
@@ -261,6 +276,26 @@ public class CatalogController : ControllerBase
 
         await _catalogContext.SaveChangesAsync();
 
+        // publish CatalogItemCreatedIntegrationEvent
+        var productCreatedEvent = new ProductCreatedIntegrationEvent()
+        {
+            AvailableStock = item.AvailableStock,
+            CatalogBrand = item.CatalogBrand,
+            CatalogBrandId = item.CatalogBrandId,
+            CatalogType = item.CatalogType,
+            CatalogTypeId = item.CatalogTypeId,
+            Description = item.Description,
+            Id = item.Id,
+            MaxStockThreshold = item.MaxStockThreshold,
+            Name = item.Name,
+            OnReorder = item.OnReorder
+        };
+        // Achieving atomicity between original Catalog database operation and the IntegrationEventLog thanks to a local transaction
+        await _catalogIntegrationEventService.SaveEventAndCatalogContextChangesAsync(productCreatedEvent);
+
+        // Publish through the Event Bus and mark the saved event as published
+        await _catalogIntegrationEventService.PublishThroughEventBusAsync(productCreatedEvent);
+
         return CreatedAtAction(nameof(ItemByIdAsync), new { id = item.Id }, null);
     }
 
@@ -282,6 +317,13 @@ public class CatalogController : ControllerBase
 
         await _catalogContext.SaveChangesAsync();
 
+        var productDeletedEvent = new ProductDeletedIntegrationEvent(product.Id);
+        // Achieving atomicity between original Catalog database operation and the IntegrationEventLog thanks to a local transaction
+        await _catalogIntegrationEventService.SaveEventAndCatalogContextChangesAsync(productDeletedEvent);
+
+        // Publish through the Event Bus and mark the saved event as published
+        await _catalogIntegrationEventService.PublishThroughEventBusAsync(productDeletedEvent);
+
         return NoContent();
     }
 

src/Services/Catalog/Catalog.API/IntegrationEvents/Events/ProductCreatedIntegrationEvent.cs

@@ -0,0 +1,39 @@
+namespace Microsoft.eShopOnContainers.Services.Catalog.API.IntegrationEvents.Events;
+
+public record ProductCreatedIntegrationEvent : IntegrationEvent
+{
+    public int Id { get; set; }
+
+    public string Name { get; set; }
+
+    public string Description { get; set; }
+
+    public decimal Price { get; set; }
+
+    public string PictureFileName { get; set; }
+
+    public string PictureUri { get; set; }
+
+    public int CatalogTypeId { get; set; }
+
+    public CatalogType CatalogType { get; set; }
+
+    public int CatalogBrandId { get; set; }
+
+    public CatalogBrand CatalogBrand { get; set; }
+
+    // Quantity in stock
+    public int AvailableStock { get; set; }
+
+    // Available stock at which we should reorder
+    public int RestockThreshold { get; set; }
+
+
+    // Maximum number of units that can be in-stock at any time (due to physicial/logistical constraints in warehouses)
+    public int MaxStockThreshold { get; set; }
+
+    /// <summary>
+    /// True if item is on reorder
+    /// </summary>
+    public bool OnReorder { get; set; }
+}

src/Services/Catalog/Catalog.API/IntegrationEvents/Events/ProductDeletedIntegrationEvent.cs

@@ -0,0 +1,11 @@
+namespace Microsoft.eShopOnContainers.Services.Catalog.API.IntegrationEvents.Events;
+
+public record ProductDeletedIntegrationEvent : IntegrationEvent
+{
+    public int ProductId { get; private init; }
+
+    public ProductDeletedIntegrationEvent(int productId)
+    {
+        ProductId = productId;
+    }
+}

src/Services/Catalog/Catalog.API/IntegrationEvents/Events/ProductStockChangedIntegrationEvent.cs

@@ -0,0 +1,20 @@
+namespace Microsoft.eShopOnContainers.Services.Catalog.API.IntegrationEvents.Events;
+
+// Integration Events notes: 
+// An Event is “something that has happened in the past”, therefore its name has to be past tense
+// An Integration Event is an event that can cause side effects to other microservices, Bounded-Contexts or external systems.
+public record ProductStockChangedIntegrationEvent : IntegrationEvent
+{
+    public int ProductId { get; private init; }
+
+    public decimal NewStock { get; private init; }
+
+    public decimal OldStock { get; private init; }
+
+    public ProductStockChangedIntegrationEvent(int productId, decimal newStock, decimal oldStock)
+    {
+        ProductId = productId;
+        NewStock = newStock;
+        OldStock = oldStock;
+    }
+}