feat: move create inventory to @medusajs/workflows (#5301)

**Why**
- We have some workflow-like flows in @medusajs/medusa. These should be moved over to the workflows package.
- Inventory Items <> Variant currently assume a 1-1 mapping. There should be support for a many-to-many mapping.

**What**
- PR introduces a feature flag for supporting many-to-many mappings for inventory and variants.
- Deletes legacy transaction handler in @medusajs/medusa.
- Adjusts existing createInventoryItems handler to remove dependency on variant data.

**Unkowns**
~~1. Couldn't find an existing test for the CreateProduct workflow. It should be tested that this still works as expected.~~
2. Have removed transaction managers as we should move to handling consistency through orchestration tooling. Are we ready for that?

packages/workflows/src/definition/index.ts

@@ -1,2 +1,3 @@
 export * from "./cart"
 export * from "./product"
+export * from "./inventory"

packages/workflows/src/definition/inventory/create-inventory-item.ts

@@ -0,0 +1,64 @@
+import { Workflows } from "../../definitions"
+import {
+  TransactionStepsDefinition,
+  WorkflowManager,
+} from "@medusajs/orchestration"
+import { exportWorkflow, pipe } from "../../helper"
+
+import { InventoryTypes, WorkflowTypes } from "@medusajs/types"
+import { InventoryHandlers } from "../../handlers"
+
+export enum CreateInventoryItemActions {
+  prepare = "prepare",
+  createInventoryItems = "createInventoryItems",
+}
+
+const workflowSteps: TransactionStepsDefinition = {
+  next: {
+    action: CreateInventoryItemActions.createInventoryItems,
+  },
+}
+
+const handlers = new Map([
+  [
+    CreateInventoryItemActions.createInventoryItems,
+    {
+      invoke: pipe(
+        {
+          inputAlias: CreateInventoryItemActions.prepare,
+          merge: true,
+          invoke: {
+            from: CreateInventoryItemActions.prepare,
+          },
+        },
+        InventoryHandlers.createInventoryItems
+      ),
+      compensate: pipe(
+        {
+          merge: true,
+          invoke: {
+            from: CreateInventoryItemActions.createInventoryItems,
+            alias:
+              InventoryHandlers.removeInventoryItems.aliases.inventoryItems,
+          },
+        },
+        InventoryHandlers.removeInventoryItems
+      ),
+    },
+  ],
+])
+
+WorkflowManager.register(
+  Workflows.CreateInventoryItems,
+  workflowSteps,
+  handlers
+)
+
+export const createInventoryItems = exportWorkflow<
+  WorkflowTypes.InventoryWorkflow.CreateInventoryItemsWorkflowInputDTO,
+  { tag: string; inventoryItem: InventoryTypes.InventoryItemDTO }[]
+>(
+  Workflows.CreateInventoryItems,
+  CreateInventoryItemActions.createInventoryItems,
+  async (data) => data
+)

packages/workflows/src/definition/inventory/index.ts

@@ -0,0 +1 @@
+export * from "./create-inventory-item"

packages/workflows/src/definition/product/create-products.ts

@@ -11,6 +11,7 @@ import {
   MiddlewaresHandlers,
   ProductHandlers,
 } from "../../handlers"
+import { prepareCreateInventoryItems } from "./prepare-create-inventory-items"
 
 export enum CreateProductsActions {
   prepare = "prepare",
@@ -175,9 +176,10 @@ const handlers = new Map([
           merge: true,
           invoke: {
             from: CreateProductsActions.createProducts,
-            alias: InventoryHandlers.createInventoryItems.aliases.products,
+            alias: prepareCreateInventoryItems.aliases.products,
           },
         },
+        prepareCreateInventoryItems,
         InventoryHandlers.createInventoryItems
       ),
       compensate: pipe(

packages/workflows/src/definition/product/prepare-create-inventory-items.ts

@@ -0,0 +1,46 @@
+import { ProductTypes } from "@medusajs/types"
+import { WorkflowArguments } from "../../helper"
+
+type AssociationTaggedVariant = ProductTypes.ProductVariantDTO & {
+  _associationTag?: string
+}
+
+type ObjectWithVariant = { variants: ProductTypes.ProductVariantDTO[] }
+
+export async function prepareCreateInventoryItems({
+  data,
+}: WorkflowArguments<{
+  products: ObjectWithVariant[]
+}>) {
+  const taggedVariants = data.products.reduce<AssociationTaggedVariant[]>(
+    (acc, product: ObjectWithVariant) => {
+      const cleanVariants = product.variants.reduce<AssociationTaggedVariant[]>(
+        (acc, variant: AssociationTaggedVariant) => {
+          if (!variant.manage_inventory) {
+            return acc
+          }
+
+          variant._associationTag = variant.id
+
+          acc.push(variant)
+          return acc
+        },
+        []
+      )
+      return acc.concat(cleanVariants)
+    },
+    []
+  )
+
+  return {
+    alias: prepareCreateInventoryItems.aliases.output,
+    value: {
+      inventoryItems: taggedVariants,
+    },
+  }
+}
+
+prepareCreateInventoryItems.aliases = {
+  products: "products",
+  output: "prepareCreateInventoryItemsOutput",
+}