Add maybe_anonymize_reporter/1

config/config.exs

@@ -364,7 +364,9 @@ config :pleroma, :activitypub,
   note_replies_output_limit: 5,
   sign_object_fetches: true,
   authorized_fetch_mode: false,
-  client_api_enabled: false
+  client_api_enabled: false,
+  anonymize_reporter: false,
+  anonymize_reporter_local_nickname: ""
 
 config :pleroma, :streamer,
   workers: 3,

config/description.exs

@@ -1790,6 +1790,23 @@ config :pleroma, :config_description, [
         key: :client_api_enabled,
         type: :boolean,
         description: "Allow client to server ActivityPub interactions"
+      },
+      %{
+        key: :anonymize_reporter,
+        type: :boolean,
+        label: "Anonymize local reports",
+        description:
+          "If true, replace local reporters with the designated local user for the copy to be sent to remote servers"
+      },
+      %{
+        key: :anonymize_reporter_local_nickname,
+        type: :string,
+        label: "Anonymized reporter",
+        description:
+          "The nickname of the designated local user that replaces the actual reporter in the copy to be sent to remote servers",
+        suggestions: [
+          "lain"
+        ]
       }
     ]
   },

lib/pleroma/web/activity_pub/utils.ex

@@ -875,6 +875,18 @@ defmodule Pleroma.Web.ActivityPub.Utils do
     {:ok, %{activity | data: new_data}}
   end
 
+  def maybe_anonymize_reporter(activity) do
+    with true <- Pleroma.Config.get([:activitypub, :anonymize_reporter]),
+         nickname when is_binary(nickname) <-
+           Pleroma.Config.get([:activitypub, :anonymize_reporter_local_nickname]),
+         %User{ap_id: ap_id, local: true} <- User.get_cached_by_nickname(nickname) do
+      activity
+      |> Map.put("actor", ap_id)
+    else
+      _ -> activity
+    end
+  end
+
   def update_activity_visibility(activity, visibility) when visibility in @valid_visibilities do
     [to, cc, recipients] =
       activity

test/pleroma/web/activity_pub/utils_test.exs

@@ -670,4 +670,64 @@ defmodule Pleroma.Web.ActivityPub.UtilsTest do
       )
     end
   end
+
+  describe "maybe_anonymize_reporter/1" do
+    setup do
+      reporter = insert(:user)
+      report = %{"actor" => reporter.ap_id}
+
+      %{
+        placeholder: insert(:user),
+        reporter: reporter,
+        report: report
+      }
+    end
+
+    test "anonymize when configured correctly", %{
+      placeholder: placeholder,
+      report: report
+    } do
+      clear_config([:activitypub, :anonymize_reporter], true)
+      clear_config([:activitypub, :anonymize_reporter_local_nickname], placeholder.nickname)
+
+      assert %{"actor" => placeholder.ap_id} == Utils.maybe_anonymize_reporter(report)
+    end
+
+    test "do not anonymize when disabled", %{
+      placeholder: placeholder,
+      reporter: reporter,
+      report: report
+    } do
+      clear_config([:activitypub, :anonymize_reporter], false)
+      clear_config([:activitypub, :anonymize_reporter_local_nickname], placeholder.nickname)
+
+      assert %{"actor" => reporter.ap_id} == Utils.maybe_anonymize_reporter(report)
+    end
+
+    test "do not anonymize when user does not exist", %{
+      placeholder: placeholder,
+      reporter: reporter,
+      report: report
+    } do
+      clear_config([:activitypub, :anonymize_reporter], true)
+
+      clear_config(
+        [:activitypub, :anonymize_reporter_local_nickname],
+        placeholder.nickname <> "MewMew"
+      )
+
+      assert %{"actor" => reporter.ap_id} == Utils.maybe_anonymize_reporter(report)
+    end
+
+    test "do not anonymize when user is not local", %{
+      reporter: reporter,
+      report: report
+    } do
+      placeholder = insert(:user, local: false)
+      clear_config([:activitypub, :anonymize_reporter], true)
+      clear_config([:activitypub, :anonymize_reporter_local_nickname], placeholder.nickname)
+
+      assert %{"actor" => reporter.ap_id} == Utils.maybe_anonymize_reporter(report)
+    end
+  end
 end