Mastodon API Account view: Remove an outdated hack

The hack with caching the follow relationship was introduced
when we still were storing it inside the follow activity, resulting in
slow queries. Now we store follow state in `FollowRelationship` table,
so this is no longer necessary.

lib/pleroma/user.ex

@@ -292,24 +292,6 @@ def ap_followers(%User{} = user), do: "#{ap_id(user)}/followers"
   def ap_following(%User{following_address: fa}) when is_binary(fa), do: fa
   def ap_following(%User{} = user), do: "#{ap_id(user)}/following"
 
-  def follow_state(%User{} = user, %User{} = target) do
-    case Utils.fetch_latest_follow(user, target) do
-      %{data: %{"state" => state}} -> state
-      # Ideally this would be nil, but then Cachex does not commit the value
-      _ -> false
-    end
-  end
-
-  def get_cached_follow_state(user, target) do
-    key = "follow_state:#{user.ap_id}|#{target.ap_id}"
-    Cachex.fetch!(:user_cache, key, fn _ -> {:commit, follow_state(user, target)} end)
-  end
-
-  @spec set_follow_state_cache(String.t(), String.t(), String.t()) :: {:ok | :error, boolean()}
-  def set_follow_state_cache(user_ap_id, target_ap_id, state) do
-    Cachex.put(:user_cache, "follow_state:#{user_ap_id}|#{target_ap_id}", state)
-  end
-
   @spec restrict_deactivated(Ecto.Query.t()) :: Ecto.Query.t()
   def restrict_deactivated(query) do
     from(u in query, where: u.deactivated != ^true)

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -503,8 +503,7 @@ def follow(follower, followed, activity_id \\ nil, local \\ true) do
   defp do_follow(follower, followed, activity_id, local) do
     with data <- make_follow_data(follower, followed, activity_id),
          {:ok, activity} <- insert(data, local),
-         :ok <- maybe_federate(activity),
-         _ <- User.set_follow_state_cache(follower.ap_id, followed.ap_id, activity.data["state"]) do
+         :ok <- maybe_federate(activity) do
       {:ok, activity}
     else
       {:error, error} -> Repo.rollback(error)

lib/pleroma/web/activity_pub/utils.ex

@@ -440,22 +440,19 @@ def update_follow_state_for_all(
     |> update(set: [data: fragment("jsonb_set(data, '{state}', ?)", ^state)])
     |> Repo.update_all([])
 
-    User.set_follow_state_cache(actor, object, state)
-
     activity = Activity.get_by_id(activity.id)
 
     {:ok, activity}
   end
 
   def update_follow_state(
-        %Activity{data: %{"actor" => actor, "object" => object}} = activity,
+        %Activity{} = activity,
         state
       ) do
     new_data = Map.put(activity.data, "state", state)
     changeset = Changeset.change(activity, data: new_data)
 
     with {:ok, activity} <- Repo.update(changeset) do
-      User.set_follow_state_cache(actor, object, state)
       {:ok, activity}
     end
   end

lib/pleroma/web/mastodon_api/views/account_view.ex

@@ -36,25 +36,18 @@ def render("relationship.json", %{user: nil, target: _target}) do
   end
 
   def render("relationship.json", %{user: %User{} = user, target: %User{} = target}) do
-    follow_state = User.get_cached_follow_state(user, target)
-
-    requested =
-      if follow_state && !User.following?(user, target) do
-        follow_state == "pending"
-      else
-        false
-      end
+    follow_state = User.get_follow_state(user, target)
 
     %{
       id: to_string(target.id),
-      following: User.following?(user, target),
+      following: follow_state == "accept",
       followed_by: User.following?(target, user),
       blocking: User.blocks_user?(user, target),
       blocked_by: User.blocks_user?(target, user),
       muting: User.mutes?(user, target),
       muting_notifications: User.muted_notifications?(user, target),
       subscribing: User.subscribed_to?(user, target),
-      requested: requested,
+      requested: follow_state == "pending",
       domain_blocking: User.blocks_domain?(user, target),
       showing_reblogs: User.showing_reblogs?(user, target),
       endorsed: false