replace `Repo.get_by(User, nickname: nickname)` with `User.get_by_nickname(nickname)`

lib/pleroma/plugs/user_fetcher_plug.ex

@@ -3,9 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Plugs.UserFetcherPlug do
-  alias Pleroma.Repo
   alias Pleroma.User
-
   import Plug.Conn
 
   def init(options) do
@@ -14,26 +12,10 @@ def init(options) do
 
   def call(conn, _options) do
     with %{auth_credentials: %{username: username}} <- conn.assigns,
-         {:ok, %User{} = user} <- user_fetcher(username) do
-      conn
-      |> assign(:auth_user, user)
+         %User{} = user <- User.get_by_nickname_or_email(username) do
+      assign(conn, :auth_user, user)
     else
       _ -> conn
     end
   end
-
-  defp user_fetcher(username_or_email) do
-    {
-      :ok,
-      cond do
-        # First, try logging in as if it was a name
-        user = Repo.get_by(User, %{nickname: username_or_email}) ->
-          user
-
-        # If we get nil, we try using it as an email
-        user = Repo.get_by(User, %{email: username_or_email}) ->
-          user
-      end
-    }
-  end
 end

lib/pleroma/web/mastodon_api/mastodon_api_controller.ex

@@ -755,7 +755,7 @@ def follow(%{assigns: %{user: follower}} = conn, %{"id" => id}) do
   end
 
   def follow(%{assigns: %{user: follower}} = conn, %{"uri" => uri}) do
-    with %User{} = followed <- Repo.get_by(User, nickname: uri),
+    with %User{} = followed <- User.get_by_nickname(uri),
          {:ok, follower, followed, _} <- CommonAPI.follow(follower, followed) do
       conn
       |> put_view(AccountView)

lib/pleroma/web/twitter_api/twitter_api.ex

@@ -227,12 +227,9 @@ def get_user(user \\ nil, params) do
         end
 
       %{"screen_name" => nickname} ->
-        case target = Repo.get_by(User, nickname: nickname) do
-          nil ->
-            {:error, "No user with such screen_name"}
-
-          _ ->
-            {:ok, target}
+        case User.get_by_nickname(nickname) do
+          nil -> {:error, "No user with such screen_name"}
+          target -> {:ok, target}
         end
 
       _ ->