wip: add ns frontend.worker.undo-redo

re-implement undo/redo, which is op-based and should work with rtc.

src/main/frontend/worker/undo_redo.cljs

@@ -0,0 +1,69 @@
+(ns frontend.worker.undo-redo
+  "undo/redo related fns and op-schema"
+  (:require [datascript.core :as d]))
+
+
+(def undo-op-schema
+  [:multi {:dispatch first}
+   [:boundary
+    [:cat :keyword]]
+   [:insert-block
+    [:cat :keyword
+     [:map
+      [:block-uuid :uuid]]]]
+   [:move-block
+    [:cat :keyword
+     [:map
+      [:block-uuid :uuid]
+      [:block-origin-left :uuid]
+      [:block-origin-parent :uuid]]]]
+   [:remove-block
+    [:cat :keyword
+     [:map
+      [:block-uuid :uuid]
+      [:block-entity-map :map]]]]
+   [:update-block
+    [:cat :keyword
+     [:map
+      [:block-uuid :uuid]
+      [:block-origin-content {:optional true} :string]
+      ;; TODO: add more attrs
+      ]]]])
+
+
+(defn reverse-op
+  [db op]
+  (let [block-uuid (:block-uuid (second op))]
+    (case (first op)
+      :boundary op
+
+      :insert-block
+      [:remove-block
+       {:block-uuid block-uuid
+        :block-entity-map (d/pull db [:block/uuid
+                                      {:block/left [:block/uuid]}
+                                      {:block/parent [:block/uuid]}
+                                      :block/created-at
+                                      :block/updated-at
+                                      :block/format
+                                      :block/properties
+                                      {:block/tags [:block/uuid]}
+                                      :block/content
+                                      {:block/page [:block/uuid]}])}]
+
+      :move-block
+      (let [b (d/entity db [:block/uuid block-uuid])]
+        [:move-block
+         {:block-uuid block-uuid
+          :block-origin-left (:block/uuid (:block/left b))
+          :block-origin-parent (:block/uuid (:block/parent b))}])
+
+      :remove-block
+      [:insert-block {:block-uuid block-uuid}]
+
+      :update-block
+      (let [block-origin-content (when (:block-origin-content op)
+                                   (:block/content (d/entity db [:block/uuid block-uuid])))]
+        [:update-block
+         (cond-> {:block-uuid block-uuid}
+           block-origin-content (assoc :block-origin-content block-origin-content))]))))