From 08062e8ce8ffbd090391f666dce7b84eb0e41d2e Mon Sep 17 00:00:00 2001
From: Andrey Antukh <niwi@niwi.nz>
Date: Tue, 27 Jul 2021 12:01:46 +0200
Subject: [PATCH] :books: Add better docstring to group creation internal
 function.

---
 .../src/app/main/data/workspace/groups.cljs   | 87 ++++++++++---------
 1 file changed, 47 insertions(+), 40 deletions(-)

diff --git a/frontend/src/app/main/data/workspace/groups.cljs b/frontend/src/app/main/data/workspace/groups.cljs
index fc88141b3..a49b8c0b0 100644
--- a/frontend/src/app/main/data/workspace/groups.cljs
+++ b/frontend/src/app/main/data/workspace/groups.cljs
@@ -36,8 +36,14 @@
         (gsh/setup selrect)
         (assoc :shapes (mapv :id shapes)))))
 
-(defn get-empty-groups
-  "Retrieve emtpy groups after group creation"
+(defn- get-empty-groups-after-group-creation
+  "An auxiliar function that finds and returns a set of ids that
+  corresponds to groups that should be deleted after a group creation.
+
+  The corner case happens when you selects two (or more) shapes that
+  belongs each one to different groups, and after creating the new
+  group, one (or many) groups can become empty because they have had a
+  single shape which is moved to the created group."
   [objects parent-id shapes]
   (let [ids (cp/clean-loops objects (into #{} (map :id) shapes))
         parents (->> ids
@@ -72,55 +78,56 @@
 
 (defn prepare-create-group
   [objects page-id shapes prefix keep-name]
-  (let [group (make-group shapes prefix keep-name)
-        frame-id (:frame-id (first shapes))
+  (let [group     (make-group shapes prefix keep-name)
+        frame-id  (:frame-id (first shapes))
         parent-id (:parent-id (first shapes))
-        rchanges [{:type :add-obj
-                   :id (:id group)
-                   :page-id page-id
-                   :frame-id frame-id
-                   :parent-id parent-id
-                   :obj group
-                   :index (::index (first shapes))}
 
-                  {:type :mov-objects
-                   :page-id page-id
-                   :parent-id (:id group)
-                   :shapes (mapv :id shapes)}]
+        rchanges  [{:type :add-obj
+                    :id (:id group)
+                    :page-id page-id
+                    :frame-id frame-id
+                    :parent-id parent-id
+                    :obj group
+                    :index (::index (first shapes))}
 
-        uchanges  (-> (mapv
-                       (fn [obj]
-                         {:type :mov-objects
-                          :page-id page-id
-                          :parent-id (:parent-id obj)
-                          :index (::index obj)
-                          :shapes [(:id obj)]}) shapes)
-                      (conj
-                       {:type :del-obj
-                        :id (:id group)
-                        :page-id page-id}))
+                   {:type :mov-objects
+                    :page-id page-id
+                    :parent-id (:id group)
+                    :shapes (mapv :id shapes)}]
 
-        ids-to-delete (get-empty-groups objects parent-id shapes)
+        uchanges  (-> (mapv (fn [obj]
+                              {:type :mov-objects
+                               :page-id page-id
+                               :parent-id (:parent-id obj)
+                               :index (::index obj)
+                               :shapes [(:id obj)]})
+                            shapes)
+                      (conj {:type :del-obj
+                             :id (:id group)
+                             :page-id page-id}))
+
+        ;; Look at the `get-empty-groups-after-group-creation`
+        ;; doctring to understand the real purpuse of this code
+        ids-to-delete (get-empty-groups-after-group-creation objects parent-id shapes)
 
         delete-group
         (fn [changes id]
-          (-> changes
-              (conj {:type :del-obj
-                     :id id
-                     :page-id page-id})))
+          (conj changes {:type :del-obj
+                         :id id
+                         :page-id page-id}))
 
         add-deleted-group
         (fn [changes id]
           (let [obj (-> (get objects id)
-                        (d/without-keys [:shapes]))]
-
-            (d/concat [{:type :add-obj
-                        :id id
-                        :page-id page-id
-                        :frame-id (:frame-id obj)
-                        :parent-id (:parent-id obj)
-                        :obj obj
-                        :index (::index obj)}] changes)))
+                        (dissoc :shapes))]
+            (into [{:type :add-obj
+                    :id id
+                    :page-id page-id
+                    :frame-id (:frame-id obj)
+                    :parent-id (:parent-id obj)
+                    :obj obj
+                    :index (::index obj)}]
+                  changes)))
 
         rchanges (->> ids-to-delete
                       (reduce delete-group rchanges))