feat: Event emitting part 1/N (Fulfillment) (#7391)

**What**
Add support for event emitting in the fulfillment module

**NOTE**
It does not include the review of the events for the abstract module factory if the method is not implemented in the module itself and rely on the default implementation

packages/core/utils/src/modules-sdk/decorators/emit-events.ts

@@ -1,16 +1,17 @@
 import { MessageAggregator } from "../../event-bus"
 import { InjectIntoContext } from "./inject-into-context"
-import {MessageAggregatorFormat} from "@medusajs/types";
+import { MessageAggregatorFormat } from "@medusajs/types"
 
-export function EmitEvents(options: MessageAggregatorFormat = {} as MessageAggregatorFormat) {
+export function EmitEvents(
+  options: MessageAggregatorFormat = {} as MessageAggregatorFormat
+) {
   return function (
     target: any,
     propertyKey: string | symbol,
     descriptor: any
   ): void {
-    const aggregator = new MessageAggregator()
     InjectIntoContext({
-      messageAggregator: () => aggregator,
+      messageAggregator: () => new MessageAggregator(),
     })(target, propertyKey, descriptor)
 
     const original = descriptor.value
@@ -18,6 +19,17 @@ export function EmitEvents(options: MessageAggregatorFormat = {} as MessageAggre
     descriptor.value = async function (...args: any[]) {
       const result = await original.apply(this, args)
 
+      if (!target.emitEvents_) {
+        const logger = Object.keys(this.__container__ ?? {}).includes("logger")
+          ? this.__container__.logger
+          : console
+        logger.warn(
+          `No emitEvents_ method found on ${target.constructor.name}. No events emitted. To be able to use the @EmitEvents() you need to have the emitEvents_ method implemented in the class.`
+        )
+      }
+
+      const argIndex = target.MedusaContextIndex_[propertyKey]
+      const aggregator = args[argIndex].messageAggregator as MessageAggregator
       await target.emitEvents_.apply(this, [aggregator.getMessages(options)])
 
       aggregator.clearMessages()

packages/core/utils/src/modules-sdk/decorators/inject-into-context.ts

@@ -1,5 +1,3 @@
-import { MessageAggregator } from "../../event-bus"
-
 export function InjectIntoContext(
   properties: Record<string, unknown | Function>
 ): MethodDecorator {

packages/core/utils/src/modules-sdk/event-builder-factory.ts

@@ -0,0 +1,67 @@
+import { Context, EventBusTypes } from "@medusajs/types"
+
+/**
+ * Factory function to create event builders for different entities
+ *
+ * @example
+ * const createdFulfillment = eventBuilderFactory({
+ *   service: Modules.FULFILLMENT,
+ *   action: CommonEvents.CREATED,
+ *   object: "fulfillment",
+ *   eventsEnum: FulfillmentEvents,
+ * })
+ *
+ * createdFulfillment({
+ *   data,
+ *   sharedContext,
+ * })
+ *
+ * @param isMainEntity
+ * @param action
+ * @param object
+ * @param eventsEnum
+ * @param service
+ */
+export function eventBuilderFactory({
+  isMainEntity,
+  action,
+  object,
+  eventsEnum,
+  service,
+}: {
+  isMainEntity?: boolean
+  action: string
+  object: string
+  eventsEnum: Record<string, string>
+  service: string
+}) {
+  return function ({
+    data,
+    sharedContext,
+  }: {
+    data: { id: string }[]
+    sharedContext: Context
+  }) {
+    if (!data.length) {
+      return
+    }
+
+    const aggregator = sharedContext.messageAggregator!
+    const messages: EventBusTypes.RawMessageFormat[] = []
+
+    data.forEach((dataItem) => {
+      messages.push({
+        service,
+        action,
+        context: sharedContext,
+        data: { id: dataItem.id },
+        eventName: isMainEntity
+          ? eventsEnum[action]
+          : eventsEnum[`${object}_${action}`],
+        object,
+      })
+    })
+
+    aggregator.saveRawMessageData(messages)
+  }
+}

packages/core/utils/src/modules-sdk/index.ts

@@ -9,3 +9,4 @@ export * from "./migration-scripts"
 export * from "./internal-module-service-factory"
 export * from "./abstract-module-service-factory"
 export * from "./definition"
+export * from "./event-builder-factory"