PleromaAPIController: Add endpoint to fetch emoji reactions.

lib/pleroma/web/pleroma_api/pleroma_api_controller.ex

@@ -8,12 +8,40 @@ defmodule Pleroma.Web.PleromaAPI.PleromaAPIController do
   import Pleroma.Web.ControllerHelper, only: [add_link_headers: 7]
 
   alias Pleroma.Activity
+  alias Pleroma.Object
+  alias Pleroma.User
   alias Pleroma.Conversation.Participation
   alias Pleroma.Web.ActivityPub.ActivityPub
   alias Pleroma.Web.CommonAPI
+  alias Pleroma.Web.MastodonAPI.AccountView
   alias Pleroma.Web.MastodonAPI.ConversationView
   alias Pleroma.Web.MastodonAPI.StatusView
 
+  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
+      reactions =
+        Enum.reduce(emoji_reactions, %{}, fn {emoji, users}, res ->
+          users =
+            users
+            |> Enum.map(&User.get_cached_by_ap_id/1)
+
+          res
+          |> Map.put(
+            emoji,
+            AccountView.render("accounts.json", %{users: users, for: user, as: :user})
+          )
+        end)
+
+      conn
+      |> json(reactions)
+    else
+      _e ->
+        conn
+        |> json(%{})
+    end
+  end
+
   def react_with_emoji(%{assigns: %{user: user}} = conn, %{"id" => activity_id, "emoji" => emoji}) do
     with {:ok, _activity, _object} <- CommonAPI.react_with_emoji(activity_id, user, emoji),
          activity = Activity.get_by_id(activity_id) do

lib/pleroma/web/router.ex

@@ -266,6 +266,12 @@ defmodule Pleroma.Web.Router do
   end
 
   scope "/api/v1/pleroma", Pleroma.Web.PleromaAPI do
+    pipe_through(:api)
+
+    get("/statuses/:id/emoji_reactions_by", PleromaAPIController, :emoji_reactions_by)
+  end
+
+  scope "/api/v1/pleroma", Pleroma.Web.PleromaAPI do
     pipe_through(:authenticated_api)
 
     scope [] do

test/web/pleroma_api/pleroma_api_controller_test.exs

@@ -8,6 +8,7 @@ defmodule Pleroma.Web.PleromaAPI.PleromaAPIControllerTest do
   alias Pleroma.Conversation.Participation
   alias Pleroma.Repo
   alias Pleroma.Web.CommonAPI
+  alias Pleroma.Web.MastodonAPI.AccountView
 
   import Pleroma.Factory
 
@@ -26,6 +27,30 @@ defmodule Pleroma.Web.PleromaAPI.PleromaAPIControllerTest do
     assert to_string(activity.id) == id
   end
 
+  test "GET /api/v1/pleroma/statuses/:id/emoji_reactions_by", %{conn: conn} do
+    user = insert(:user)
+    other_user = insert(:user)
+
+    {:ok, activity} = CommonAPI.post(user, %{"status" => "#cofe"})
+
+    result =
+      conn
+      |> get("/api/v1/pleroma/statuses/#{activity.id}/emoji_reactions_by")
+      |> json_response(200)
+
+    assert result == %{}
+
+    {:ok, _, _} = CommonAPI.react_with_emoji(activity.id, other_user, "🎅")
+
+    result =
+      conn
+      |> get("/api/v1/pleroma/statuses/#{activity.id}/emoji_reactions_by")
+      |> json_response(200)
+
+    [represented_user] = result["🎅"]
+    assert represented_user["id"] == other_user.id
+  end
+
   test "/api/v1/pleroma/conversations/:id", %{conn: conn} do
     user = insert(:user)
     other_user = insert(:user)