2 files changed, 21 insertions, 12 deletions
diff --git a/editor/state/storage.ml b/editor/state/storage.ml
index 1bb8b81..4688881 100755
--- a/editor/state/storage.ml
+++ b/editor/state/storage.ml
@@ -58,20 +58,29 @@ let load'
 
 (** Save the view *)
 let save'
-  : check:(content Js.t -> bool) -> content Js.t -> Jstr.t -> (bool, Jv.Error.t) result
+  : check:(previous:content Js.t -> update:content Js.t -> bool) -> content Js.t -> Jstr.t -> (bool, Jv.Error.t) result
   = fun ~check object_content key ->
 
-    (* First load the content from the storage *)
-    match check (load' key) with
-    | false ->
-      Ok false
-    | true ->
+    (* First load the content from the storage. If there is already a note
+       with the same id, send the two notes to the checker to ensure we
+       really need to save it. *)
+    let stored = load' key in
+
+    let process () =
       let storage = Brr_io.Storage.local G.window in
       let operation = Brr_io.Storage.set_item
           storage
           key
           (Json.encode @@ Jv.Id.to_jv @@ object_content) in
       Result.map (fun () -> true) operation
+    in
+
+    Js.Opt.case stored##.date
+      (process)
+      (fun _ -> match check ~previous:stored ~update:object_content with
+         | false -> Ok false
+         | true -> process ()
+      )
 
 
 (** [load pm schema content f] will try load the content stored in the local
@@ -89,7 +98,7 @@ let load
       load' key
 
 let save
-  : check:(content Js.t -> bool) -> content Js.t -> Jstr.t option -> (bool, Jv.Error.t) result
+  : check:(previous:content Js.t -> update:content Js.t -> bool) -> content Js.t -> Jstr.t option -> (bool, Jv.Error.t) result
   = fun ~check object_content key ->
     match key with
     | None ->
@@ -159,8 +168,8 @@ let to_json
     Brr.Json.encode (Jv.Id.to_jv pages)
 
 let of_json
-  : Jstr.t -> (unit, Jv.Error.t) result
-  = fun json ->
+  : check:(previous:content Js.t -> update:content Js.t -> bool) -> Jstr.t -> (unit, Jv.Error.t) result
+  = fun ~check json ->
     let result = Json.decode json in
     Result.map
       (fun v ->
@@ -174,7 +183,7 @@ let of_json
                end in
                ignore @@
                save
-                 ~check:(fun _ -> true)
+                 ~check
                  content
                  key
              ))
diff --git a/editor/state/storage.mli b/editor/state/storage.mli
index 4d022d1..cad2982 100755
--- a/editor/state/storage.mli
+++ b/editor/state/storage.mli
@@ -25,7 +25,7 @@ val load
   : Jstr.t option -> content Js.t
 
 val save
-  : check:(content Js.t -> bool) -> content Js.t -> Jstr.t option -> (bool, Jv.Error.t) result
+  : check:(previous:content Js.t -> update:content Js.t -> bool) -> content Js.t -> Jstr.t option -> (bool, Jv.Error.t) result
 
 (** Remove the page from the storage. *)
 val delete 
@@ -39,4 +39,4 @@ val to_json
   : unit -> Jstr.t
 
 val of_json
-  : Jstr.t -> (unit, Jv.Error.t) result
+  : check:(previous:content Js.t -> update:content Js.t -> bool) -> Jstr.t -> (unit, Jv.Error.t) result