feat: add a line item to an order edit (#2243)

**What**
- Implement adding a line item to order (edit)

**How**
- _by implementing the following "flow"_
  - generate a line item
  - computing line item adjustments for that line item
  - creating tax lines
  - creating a change record

**Testing**
- **_integration tests_**
  - check if line item and order item change objects are created (with correct tax lines)
  - line item adjustments are generated if
    - fixed discount is applied to cart
    - percentage discount is applied
- **_unit tests_** 
  - ensure that methods from Inventory, LineItem, LineItemAdjustment etc. services are called 

---

RESOLVES CORE-495

packages/medusa/src/api/routes/admin/draft-orders/create-line-item.ts

@@ -3,13 +3,7 @@ import {
   DraftOrderService,
   LineItemService,
 } from "../../../../services"
-import {
-  IsBoolean,
-  IsInt,
-  IsObject,
-  IsOptional,
-  IsString,
-} from "class-validator"
+import { IsInt, IsObject, IsOptional, IsString } from "class-validator"
 import {
   defaultAdminDraftOrdersCartFields,
   defaultAdminDraftOrdersCartRelations,
@@ -17,7 +11,6 @@ import {
 } from "."
 
 import { EntityManager } from "typeorm"
-import { FlagRouter } from "../../../../utils/flag-router"
 import { MedusaError } from "medusa-core-utils"
 import { validator } from "../../../../utils/validator"
 

packages/medusa/src/api/routes/admin/order-edits/add-line-item.ts

@@ -0,0 +1,101 @@
+import { Request, Response } from "express"
+import { IsInt, IsOptional, IsString } from "class-validator"
+import { EntityManager } from "typeorm"
+
+import { OrderEditService } from "../../../../services"
+import {
+  defaultOrderEditFields,
+  defaultOrderEditRelations,
+} from "../../../../types/order-edit"
+
+/**
+ * @oas [post] /order-edits/{id}/items
+ * operationId: "PostOrderEditsEditLineItems"
+ * summary: "Add an line item to an order (edit)"
+ * description: "Create an OrderEdit LineItem."
+ * parameters:
+ *   - (path) id=* {string} The ID of the Order Edit.
+ * x-authenticated: true
+ * x-codeSamples:
+ *   - lang: JavaScript
+ *     label: JS Client
+ *     source: |
+ *       import Medusa from "@medusajs/medusa-js"
+ *       const medusa = new Medusa({ baseUrl: MEDUSA_BACKEND_URL, maxRetries: 3 })
+ *       // must be previously logged in or use api token
+ *       medusa.admin.orderEdit.addLineItem(order_edit_id, { variant_id, quantity })
+ *        .then(({ order_edit }) => {
+ *           console.log(order_edit.id)
+ *        })
+ *   - lang: Shell
+ *     label: cURL
+ *     source: |
+ *       curl --location --request POST 'https://medusa-url.com/admin/order-edits/{id}/items' \
+ *       --header 'Authorization: Bearer {api_token}'
+ *       -d '{ "variant_id": "some_variant_id", "quantity": 3 }'
+ * security:
+ *   - api_token: []
+ *   - cookie_auth: []
+ * tags:
+ *   - OrderEdit
+ * responses:
+ *   200:
+ *     description: OK
+ *     content:
+ *       application/json:
+ *         schema:
+ *           properties:
+ *             order_edit:
+ *               $ref: "#/components/schemas/order_edit"
+ *   "400":
+ *     $ref: "#/components/responses/400_error"
+ *   "401":
+ *     $ref: "#/components/responses/unauthorized"
+ *   "404":
+ *     $ref: "#/components/responses/not_found_error"
+ *   "409":
+ *     $ref: "#/components/responses/invalid_state_error"
+ *   "422":
+ *     $ref: "#/components/responses/invalid_request_error"
+ *   "500":
+ *     $ref: "#/components/responses/500_error"
+ */
+export default async (req: Request, res: Response) => {
+  const orderEditService = req.scope.resolve(
+    "orderEditService"
+  ) as OrderEditService
+
+  const { id } = req.params
+
+  const manager = req.scope.resolve("manager") as EntityManager
+
+  const data = req.validatedBody as AdminPostOrderEditsEditLineItemsReq
+
+  await manager.transaction(async (transactionManager) => {
+    await orderEditService
+      .withTransaction(transactionManager)
+      .addLineItem(id, data)
+  })
+
+  let orderEdit = await orderEditService.retrieve(id, {
+    select: defaultOrderEditFields,
+    relations: defaultOrderEditRelations,
+  })
+
+  orderEdit = await orderEditService.decorateTotals(orderEdit)
+
+  res.status(200).send({
+    order_edit: orderEdit,
+  })
+}
+
+export class AdminPostOrderEditsEditLineItemsReq {
+  @IsString()
+  variant_id: string
+
+  @IsInt()
+  quantity: number
+
+  @IsOptional()
+  metadata?: Record<string, unknown> | undefined
+}

packages/medusa/src/api/routes/admin/order-edits/delete-order-edit.ts

@@ -8,7 +8,7 @@ import { OrderEditService } from "../../../../services"
  * description: "Deletes an Order Edit"
  * x-authenticated: true
  * parameters:
- *   - (path) id=* {string} The ID of the Note to delete.
+ *   - (path) id=* {string} The ID of the Order Edit to delete.
  * x-codeSamples:
  *   - lang: JavaScript
  *     label: JS Client

packages/medusa/src/api/routes/admin/order-edits/index.ts

@@ -14,6 +14,7 @@ import {
 import { OrderEdit } from "../../../../models"
 import { AdminPostOrderEditsOrderEditReq } from "./update-order-edit"
 import { AdminPostOrderEditsReq } from "./create-order-edit"
+import { AdminPostOrderEditsEditLineItemsReq } from "./add-line-item"
 import { AdminPostOrderEditsEditLineItemsLineItemReq } from "./update-order-edit-line-item"
 
 const route = Router()
@@ -52,6 +53,12 @@ export default (app) => {
     middlewares.wrap(require("./cancel-order-edit").default)
   )
 
+  route.post(
+    "/:id/items",
+    transformBody(AdminPostOrderEditsEditLineItemsReq),
+    middlewares.wrap(require("./add-line-item").default)
+  )
+
   route.delete("/:id", middlewares.wrap(require("./delete-order-edit").default))
 
   route.delete(
@@ -86,3 +93,5 @@ export type AdminOrderEditItemChangeDeleteRes = {
 export * from "./update-order-edit"
 export * from "./update-order-edit-line-item"
 export * from "./create-order-edit"
+
+export * from "./add-line-item"