[FEAT/BE] fixing fifo fallback recording,fixing backdate and fixing product category

internal/modules/purchases/services/purchase.service.go

@@ -1064,6 +1064,15 @@ func (s *purchaseService) ReceiveProducts(c *fiber.Ctx, id uint, req *validation
 			if err != nil {
 				return err
 			}
+			// Safety: ensure the PW we got matches the purchase item product.
+			if pwDetail, err := pwRepoTx.GetDetailByID(c.Context(), pwID); err != nil {
+				return err
+			} else if pwDetail.ProductId != uint(item.ProductId) {
+				return fiber.NewError(
+					fiber.StatusBadRequest,
+					fmt.Sprintf("Product warehouse %d belongs to product %d, not purchase item product %d", pwID, pwDetail.ProductId, item.ProductId),
+				)
+			}
 			newPWID = &pwID
 
 			deltaQty := prep.receivedQty - item.TotalQty