4 files changed, 52 insertions, 92 deletions

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 4c29dda35..446355c1e 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -20,8 +20,11 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
   alias Pleroma.Repo
   alias Pleroma.Upload
   alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.Builder
   alias Pleroma.Web.ActivityPub.MRF
+  alias Pleroma.Web.ActivityPub.Pipeline
   alias Pleroma.Web.ActivityPub.Transmogrifier
+  alias Pleroma.Web.ActivityPub.Utils
   alias Pleroma.Web.Streamer
   alias Pleroma.Web.WebFinger
   alias Pleroma.Workers.BackgroundWorker
@@ -322,22 +325,17 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     end
   end
 
-  @spec unfollow(User.t(), User.t(), String.t() | nil, boolean()) ::
-          {:ok, Activity.t()} | nil | {:error, any()}
-  def unfollow(follower, followed, activity_id \\ nil, local \\ true) do
-    with {:ok, result} <-
-           Repo.transaction(fn -> do_unfollow(follower, followed, activity_id, local) end) do
+  @spec unfollow(User.t(), User.t()) :: {:ok, Activity.t()} | nil | {:error, any()}
+  def unfollow(follower, followed) do
+    with {:ok, result} <- Repo.transaction(fn -> do_unfollow(follower, followed) end) do
       result
     end
   end
 
-  defp do_unfollow(follower, followed, activity_id, local) do
-    with %Activity{} = follow_activity <- fetch_latest_follow(follower, followed),
-         {:ok, follow_activity} <- update_follow_state(follow_activity, "cancelled"),
-         unfollow_data <- make_unfollow_data(follower, followed, follow_activity, activity_id),
-         {:ok, activity} <- insert(unfollow_data, local),
-         _ <- notify_and_stream(activity),
-         :ok <- maybe_federate(activity) do
+  defp do_unfollow(follower, followed) do
+    with %Activity{} = follow_activity <- Utils.fetch_latest_follow(follower, followed),
+         {:ok, unfollow_data, _meta} <- Builder.undo(follower, follow_activity),
+         {:ok, activity, _meta} <- Pipeline.common_pipeline(unfollow_data, local: true) do
       {:ok, activity}
     else
       nil -> nil
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index b0ec84ade..b9ec33a55 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -254,10 +254,12 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   end
 
   @impl true
-  def handle(%{data: %{"type" => "Undo", "object" => undone_object}} = object, meta) do
-    with undone_object <- Activity.get_by_ap_id(undone_object),
-         :ok <- handle_undoing(undone_object) do
+  def handle(%{data: %{"type" => "Undo", "object" => undone_activity}} = object, meta) do
+    with undone_activity <- Activity.get_by_ap_id(undone_activity),
+         :ok <- handle_undoing(undone_activity) do
       {:ok, object, meta}
+    else
+      e -> {:error, e}
     end
   end
 
@@ -456,35 +458,48 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
     end
   end
 
-  def handle_undoing(%{data: %{"type" => "Like"}} = object) do
-    object.data["object"]
+  def handle_undoing(%{data: %{"type" => "Like"}} = activity) do
+    activity.data["object"]
     |> Object.get_by_ap_id()
-    |> undo_like(object)
+    |> undo_like(activity)
   end
 
-  def handle_undoing(%{data: %{"type" => "EmojiReact"}} = object) do
-    with %Object{} = reacted_object <- Object.get_by_ap_id(object.data["object"]),
-         {:ok, _} <- Utils.remove_emoji_reaction_from_object(object, reacted_object),
-         {:ok, _} <- Repo.delete(object) do
+  def handle_undoing(%{data: %{"type" => "EmojiReact"}} = activity) do
+    with %Object{} = reacted_object <- Object.get_by_ap_id(activity.data["object"]),
+         {:ok, _} <- Utils.remove_emoji_reaction_from_object(activity, reacted_object),
+         {:ok, _} <- Repo.delete(activity) do
       :ok
     end
   end
 
-  def handle_undoing(%{data: %{"type" => "Announce"}} = object) do
-    with %Object{} = liked_object <- Object.get_by_ap_id(object.data["object"]),
-         {:ok, _} <- Utils.remove_announce_from_object(object, liked_object),
-         {:ok, _} <- Repo.delete(object) do
+  def handle_undoing(%{data: %{"type" => "Announce"}} = activity) do
+    with %Object{} = liked_object <- Object.get_by_ap_id(activity.data["object"]),
+         {:ok, _} <- Utils.remove_announce_from_object(activity, liked_object),
+         {:ok, _} <- Repo.delete(activity) do
       :ok
     end
   end
 
   def handle_undoing(
-        %{data: %{"type" => "Block", "actor" => blocker, "object" => blocked}} = object
+        %{data: %{"type" => "Block", "actor" => blocker, "object" => blocked}} = activity
       ) do
     with %User{} = blocker <- User.get_cached_by_ap_id(blocker),
          %User{} = blocked <- User.get_cached_by_ap_id(blocked),
          {:ok, _} <- User.unblock(blocker, blocked),
-         {:ok, _} <- Repo.delete(object) do
+         {:ok, _} <- Repo.delete(activity) do
+      :ok
+    end
+  end
+
+  def handle_undoing(
+        %{data: %{"type" => "Follow", "object" => followed, "actor" => follower}} = activity
+      ) do
+    with %User{} = follower <- User.get_cached_by_ap_id(follower),
+         %User{} = followed <- User.get_cached_by_ap_id(followed),
+         {:ok, _activity} <- Utils.update_follow_state_for_all(activity, "reject"),
+         {:ok, nil} <- FollowingRelationship.update(follower, followed, :follow_reject) do
+      Notification.dismiss(activity)
+
       :ok
     end
   end
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 142af1a13..6d49f0141 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -516,52 +516,30 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{
-          "type" => "Undo",
-          "object" => %{"type" => "Follow", "object" => followed},
-          "actor" => follower,
-          "id" => id
-        } = _data,
-        _options
-      ) do
-    with %User{local: true} = followed <- User.get_cached_by_ap_id(followed),
-         {:ok, %User{} = follower} <- User.get_or_fetch_by_ap_id(follower),
-         {:ok, activity} <- ActivityPub.unfollow(follower, followed, id, false) do
-      User.unfollow(follower, followed)
-      {:ok, activity}
-    else
-      _e -> :error
-    end
-  end
-
-  def handle_incoming(
-        %{
-          "type" => "Undo",
-          "object" => %{"type" => type}
-        } = data,
+        %{"type" => "Undo", "object" => %{"type" => objtype, "id" => object_id}} = data,
         _options
       )
-      when type in ["Like", "EmojiReact", "Announce", "Block"] do
-    with {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
+      when objtype in ~w[Like EmojiReact Announce Block Follow] do
+    with {:ok, %User{}} <- ObjectValidator.fetch_actor(data),
+         {_, %Activity{}} <- {:exists, Activity.get_by_ap_id(object_id)},
+         {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
+    else
+      {:error, _} = e -> e
+      e -> {:error, e}
     end
   end
 
   # For Undos that don't have the complete object attached, try to find it in our database.
-  def handle_incoming(
-        %{
-          "type" => "Undo",
-          "object" => object
-        } = activity,
-        options
-      )
+  def handle_incoming(%{"type" => "Undo", "object" => object} = activity, options)
       when is_binary(object) do
     with %Activity{data: data} <- Activity.get_by_ap_id(object) do
       activity
       |> Map.put("object", data)
       |> handle_incoming(options)
     else
-      _e -> :error
+      {:error, _} = e -> e
+      e -> {:error, e}
     end
   end
 
diff --git a/lib/pleroma/web/activity_pub/utils.ex b/lib/pleroma/web/activity_pub/utils.ex
index 1df53f79a..6bed3dffa 100644
--- a/lib/pleroma/web/activity_pub/utils.ex
+++ b/lib/pleroma/web/activity_pub/utils.ex
@@ -572,25 +572,6 @@ defmodule Pleroma.Web.ActivityPub.Utils do
     |> Maps.put_if_present("id", activity_id)
   end
 
-  def make_undo_data(
-        %User{ap_id: actor, follower_address: follower_address},
-        %Activity{
-          data: %{"id" => undone_activity_id, "context" => context},
-          actor: undone_activity_actor
-        },
-        activity_id \\ nil
-      ) do
-    %{
-      "type" => "Undo",
-      "actor" => actor,
-      "object" => undone_activity_id,
-      "to" => [follower_address, undone_activity_actor],
-      "cc" => [Pleroma.Constants.as_public()],
-      "context" => context
-    }
-    |> Maps.put_if_present("id", activity_id)
-  end
-
   @spec add_announce_to_object(Activity.t(), Object.t()) ::
           {:ok, Object.t()} | {:error, Ecto.Changeset.t()}
   def add_announce_to_object(
@@ -624,18 +605,6 @@ defmodule Pleroma.Web.ActivityPub.Utils do
 
   defp take_announcements(_), do: []
 
-  #### Unfollow-related helpers
-
-  def make_unfollow_data(follower, followed, follow_activity, activity_id) do
-    %{
-      "type" => "Undo",
-      "actor" => follower.ap_id,
-      "to" => [followed.ap_id],
-      "object" => follow_activity.data
-    }
-    |> Maps.put_if_present("id", activity_id)
-  end
-
   #### Block-related helpers
   @spec fetch_latest_block(User.t(), User.t()) :: Activity.t() | nil
   def fetch_latest_block(%User{ap_id: blocker_id}, %User{ap_id: blocked_id}) do