3 files changed, 47 insertions, 32 deletions

diff --git a/lib/pleroma/web/activity_pub/utils.ex b/lib/pleroma/web/activity_pub/utils.ex
index db7084246..4def431f1 100644
--- a/lib/pleroma/web/activity_pub/utils.ex
+++ b/lib/pleroma/web/activity_pub/utils.ex
@@ -312,19 +312,12 @@ defmodule Pleroma.Web.ActivityPub.Utils do
     |> Map.put("content", emoji)
   end
 
-  @spec update_element_in_object(String.t(), list(any), Object.t()) ::
+  @spec update_element_in_object(String.t(), list(any), Object.t(), integer() | nil) ::
           {:ok, Object.t()} | {:error, Ecto.Changeset.t()}
-  def update_element_in_object(property, element, object) do
+  def update_element_in_object(property, element, object, count \\ nil) do
     length =
-      if is_map(element) do
-        element
-        |> Map.values()
-        |> List.flatten()
-        |> length()
-      else
-        element
-        |> length()
-      end
+      count ||
+        length(element)
 
     data =
       Map.merge(
@@ -344,29 +337,52 @@ defmodule Pleroma.Web.ActivityPub.Utils do
         %Activity{data: %{"content" => emoji, "actor" => actor}},
         object
       ) do
-    reactions = object.data["reactions"] || %{}
-    emoji_actors = reactions[emoji] || []
-    new_emoji_actors = [actor | emoji_actors] |> Enum.uniq()
-    new_reactions = Map.put(reactions, emoji, new_emoji_actors)
-    update_element_in_object("reaction", new_reactions, object)
+    reactions = object.data["reactions"] || []
+
+    new_reactions =
+      case Enum.find_index(reactions, fn [candidate, _] -> emoji == candidate end) do
+        nil ->
+          reactions ++ [[emoji, [actor]]]
+
+        index ->
+          List.update_at(
+            reactions,
+            index,
+            fn [emoji, users] -> [emoji, Enum.uniq([actor | users])] end
+          )
+      end
+
+    count = emoji_count(new_reactions)
+
+    update_element_in_object("reaction", new_reactions, object, count)
+  end
+
+  def emoji_count(reactions_list) do
+    Enum.reduce(reactions_list, 0, fn [_, users], acc -> acc + length(users) end)
   end
 
   def remove_emoji_reaction_from_object(
         %Activity{data: %{"content" => emoji, "actor" => actor}},
         object
       ) do
-    reactions = object.data["reactions"] || %{}
-    emoji_actors = reactions[emoji] || []
-    new_emoji_actors = List.delete(emoji_actors, actor)
+    reactions = object.data["reactions"] || []
 
     new_reactions =
-      if new_emoji_actors == [] do
-        Map.delete(reactions, emoji)
-      else
-        Map.put(reactions, emoji, new_emoji_actors)
+      case Enum.find_index(reactions, fn [candidate, _] -> emoji == candidate end) do
+        nil ->
+          reactions
+
+        index ->
+          List.update_at(
+            reactions,
+            index,
+            fn [emoji, users] -> [emoji, List.delete(users, actor)] end
+          )
+          |> Enum.reject(fn [_, users] -> Enum.empty?(users) end)
       end
 
-    update_element_in_object("reaction", new_reactions, object)
+    count = emoji_count(new_reactions)
+    update_element_in_object("reaction", new_reactions, object, count)
   end
 
   @spec add_like_to_object(Activity.t(), Object.t()) ::
diff --git a/lib/pleroma/web/mastodon_api/views/status_view.ex b/lib/pleroma/web/mastodon_api/views/status_view.ex
index b59ac39bc..64a97896a 100644
--- a/lib/pleroma/web/mastodon_api/views/status_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/status_view.ex
@@ -255,12 +255,11 @@ defmodule Pleroma.Web.MastodonAPI.StatusView do
 
     emoji_reactions =
       with %{data: %{"reactions" => emoji_reactions}} <- object do
-        Enum.map(emoji_reactions, fn {emoji, users} ->
-          {emoji, length(users)}
+        Enum.map(emoji_reactions, fn [emoji, users] ->
+          [emoji, length(users)]
         end)
-        |> Enum.into(%{})
       else
-        _ -> %{}
+        _ -> []
       end
 
     %{
diff --git a/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex b/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
index 3285dc11b..bb19836ae 100644
--- a/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
+++ b/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
@@ -43,21 +43,21 @@ defmodule Pleroma.Web.PleromaAPI.PleromaAPIController do
 
   def emoji_reactions_by(%{assigns: %{user: user}} = conn, %{"id" => activity_id}) do
     with %Activity{} = activity <- Activity.get_by_id_with_object(activity_id),
-         %Object{data: %{"reactions" => emoji_reactions}} <- Object.normalize(activity) do
+         %Object{data: %{"reactions" => emoji_reactions}} when is_list(emoji_reactions) <-
+           Object.normalize(activity) do
       reactions =
         emoji_reactions
-        |> Enum.map(fn {emoji, users} ->
+        |> Enum.map(fn [emoji, users] ->
           users = Enum.map(users, &User.get_cached_by_ap_id/1)
           {emoji, AccountView.render("index.json", %{users: users, for: user, as: :user})}
         end)
-        |> Enum.into(%{})
 
       conn
       |> json(reactions)
     else
       _e ->
         conn
-        |> json(%{})
+        |> json([])
     end
   end