Add support for `account_id` param to filter notifications by the account

CHANGELOG.md

@@ -86,6 +86,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Mastodon API: `/api/v1/update_credentials` accepts `actor_type` field.
 - Captcha: Support native provider
 - Captcha: Enable by default
+- Mastodon API: Add support for `account_id` param to filter notifications by the account
 </details>
 
 ### Fixed

lib/pleroma/web/mastodon_api/mastodon_api.ex

@@ -56,6 +56,7 @@ def get_notifications(user, params \\ %{}) do
     user
     |> Notification.for_user_query(options)
     |> restrict(:exclude_types, options)
+    |> restrict(:account_id, options)
     |> Pagination.fetch_paginated(params)
   end
 
@@ -71,7 +72,8 @@ defp cast_params(params) do
       exclude_visibilities: {:array, :string},
       reblogs: :boolean,
       with_muted: :boolean,
-      with_move: :boolean
+      with_move: :boolean,
+      account_id: :string
     }
 
     changeset = cast({%{}, param_types}, params, Map.keys(param_types))
@@ -88,5 +90,12 @@ defp restrict(query, :exclude_types, %{exclude_types: mastodon_types = [_ | _]})
     |> where([q, a], not fragment("? @> ARRAY[?->>'type']::varchar[]", ^ap_types, a.data))
   end
 
+  defp restrict(query, :account_id, %{account_id: account_id}) do
+    case User.get_cached_by_id(account_id) do
+      %{ap_id: ap_id} -> where(query, [n, a], a.actor == ^ap_id)
+      _ -> where(query, [n, a], a.actor == "fake ap id")
+    end
+  end
+
   defp restrict(query, _, _), do: query
 end

test/web/mastodon_api/controllers/notification_controller_test.exs

@@ -463,6 +463,29 @@ test "see move notifications with `with_move` parameter", %{
     assert length(json_response(conn, 200)) == 1
   end
 
+  describe "from specified user" do
+    test "account_id", %{conn: conn} do
+      user = insert(:user)
+      %{id: account_id} = other_user1 = insert(:user)
+      other_user2 = insert(:user)
+
+      {:ok, _activity} = CommonAPI.post(other_user1, %{"status" => "hi @#{user.nickname}"})
+      {:ok, _activity} = CommonAPI.post(other_user2, %{"status" => "bye @#{user.nickname}"})
+
+      assert [%{"account" => %{"id" => ^account_id}}] =
+               conn
+               |> assign(:user, user)
+               |> get("/api/v1/notifications", %{account_id: account_id})
+               |> json_response(200)
+
+      assert [] =
+               conn
+               |> assign(:user, user)
+               |> get("/api/v1/notifications", %{account_id: "cofe"})
+               |> json_response(200)
+    end
+  end
+
   defp get_notification_id_by_activity(%{id: id}) do
     Notification
     |> Repo.get_by(activity_id: id)