Simplify the page changes watcher of history.

src/uxbox/main/data/history.cljs

@@ -89,39 +89,22 @@
   ([id params]
    (map->FetchPageHistory (assoc params :id id))))
 
-;; --- Clean Page History
-
-(defrecord CleanPageHistory []
-  rs/UpdateEvent
-  (-apply-update [_ state]
-    (assoc-in state [:workspace :history] {})))
-
-(defn clean-page-history
-  []
-  (CleanPageHistory.))
-
-(defn clean-page-history?
-  [v]
-  (instance? CleanPageHistory v))
-
 ;; --- Watch Page Changes
 
-(defrecord WatchPageChanges []
-  rs/WatchEvent
-  (-apply-watch [_ state s]
-    (let [stoper (->> (rx/filter clean-page-history? s)
-                      (rx/take 1))]
-      (->> (rx/filter udp/page-synced? s)
-           (rx/take-until stoper)
-           (rx/delay 1000)
-           (rx/map (comp :id :page))
-           (rx/mapcat #(rx/of
-                        (fetch-page-history %)
-                        (fetch-pinned-page-history %)))))))
-
 (defn watch-page-changes
+  "A function that starts watching for `IPageUpdate`
+  events emited to the global event stream and just
+  reacts on them emiting an other event that just
+  persists the state of the page in an undo stack."
   []
-  (WatchPageChanges.))
+  (letfn [(on-value [id]
+            (rs/emit! (fetch-page-history id)
+                      (fetch-pinned-page-history id)))]
+    (as-> rs/stream $
+      (rx/filter udp/page-synced? $)
+      (rx/delay 500 $)
+      (rx/map (comp :id :page) $)
+      (rx/on-value $ on-value))))
 
 ;; --- Select Page History
 

src/uxbox/main/ui/workspace.cljs

@@ -38,8 +38,7 @@
 (defn- workspace-will-mount
   [own]
   (let [[projectid pageid] (:rum/args own)]
-    (rs/emit! (dw/initialize projectid pageid)
-              (udh/watch-page-changes))
+    (rs/emit! (dw/initialize projectid pageid))
     own))
 
 (defn- workspace-did-mount
@@ -47,23 +46,25 @@
   (let [[projectid pageid] (:rum/args own)
         sub1 (scroll/watch-scroll-interactions own)
         sub2 (udp/watch-page-changes pageid)
+        sub3 (udh/watch-page-changes)
         dom (mx/ref-node own "workspace-canvas")]
 
     ;; Set initial scroll position
     (set! (.-scrollLeft dom) (* c/canvas-start-scroll-x @wb/zoom-ref))
     (set! (.-scrollTop dom) (* c/canvas-start-scroll-y @wb/zoom-ref))
 
-    (assoc own ::sub1 sub1 ::sub2 sub2)))
+    (assoc own
+           ::sub1 sub1
+           ::sub2 sub2
+           ::sub3 sub3)))
 
 (defn- workspace-will-unmount
   [own]
-  (rs/emit! (udh/clean-page-history))
-
   ;; Close subscriptions
   (.close (::sub1 own))
   (.close (::sub2 own))
-
-  (dissoc own ::sub1 ::sub2))
+  (.close (::sub3 own))
+  (dissoc own ::sub1 ::sub2 ::sub3))
 
 (defn- workspace-did-remount
   [old-state state]