feat(dashboard) admin 3.0 return creation (#6713)

**What**
- request return flow

Co-authored-by: Kasper Fabricius Kristensen <45367945+kasperkristensen@users.noreply.github.com>

packages/admin-next/dashboard/src/lib/cast-number.ts

@@ -0,0 +1,6 @@
+/**
+ * Helper function to cast a z.union([z.number(), z.string()]) to a number
+ */
+export const castNumber = (number: number | string) => {
+  return typeof number === "string" ? Number(number.replace(",", ".")) : number
+}

packages/admin-next/dashboard/src/lib/rma.ts

@@ -0,0 +1,75 @@
+import { ClaimItem, LineItem, Order } from "@medusajs/medusa"
+
+/**
+ * Return line items that are returnable from an order
+ * @param order
+ * @param isClaim
+ */
+export const getAllReturnableItems = (
+  order: Omit<Order, "beforeInserts">,
+  isClaim: boolean
+) => {
+  let orderItems = order.items.reduce(
+    (map, obj) =>
+      map.set(obj.id, {
+        ...obj,
+      }),
+    new Map<string, Omit<LineItem, "beforeInsert">>()
+  )
+
+  let claimedItems: ClaimItem[] = []
+
+  if (order.claims && order.claims.length) {
+    for (const claim of order.claims) {
+      if (claim.return_order?.status !== "canceled") {
+        claim.claim_items = claim.claim_items ?? []
+        claimedItems = [...claimedItems, ...claim.claim_items]
+      }
+
+      if (
+        claim.fulfillment_status === "not_fulfilled" &&
+        claim.payment_status === "na"
+      ) {
+        continue
+      }
+
+      if (claim.additional_items && claim.additional_items.length) {
+        orderItems = claim.additional_items
+          .filter(
+            (it) =>
+              it.shipped_quantity ||
+              it.shipped_quantity === it.fulfilled_quantity
+          )
+          .reduce((map, obj) => map.set(obj.id, { ...obj }), orderItems)
+      }
+    }
+  }
+
+  if (!isClaim) {
+    if (order.swaps && order.swaps.length) {
+      for (const swap of order.swaps) {
+        if (swap.fulfillment_status === "not_fulfilled") {
+          continue
+        }
+
+        orderItems = swap.additional_items.reduce(
+          (map, obj) =>
+            map.set(obj.id, {
+              ...obj,
+            }),
+          orderItems
+        )
+      }
+    }
+  }
+
+  for (const item of claimedItems) {
+    const i = orderItems.get(item.item_id)
+    if (i) {
+      i.quantity = i.quantity - item.quantity
+      i.quantity !== 0 ? orderItems.set(i.id, i) : orderItems.delete(i.id)
+    }
+  }
+
+  return [...orderItems.values()]
+}