From d877d2a4e7449e942b4d192f283824eebcade563 Mon Sep 17 00:00:00 2001
From: Tusooa Zhu <tusooa@kazv.moe>
Date: Sun, 24 Jul 2022 00:02:39 -0400
Subject: [PATCH] Make HashtagPolicy history-aware

---
 .../web/activity_pub/mrf/hashtag_policy.ex    | 47 ++++++++++---
 .../activity_pub/mrf/hashtag_policy_test.exs  | 70 +++++++++++++++++++
 2 files changed, 107 insertions(+), 10 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/mrf/hashtag_policy.ex b/lib/pleroma/web/activity_pub/mrf/hashtag_policy.ex
index 2142b7add..b73fd974c 100644
--- a/lib/pleroma/web/activity_pub/mrf/hashtag_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/hashtag_policy.ex
@@ -16,6 +16,9 @@ defmodule Pleroma.Web.ActivityPub.MRF.HashtagPolicy do
 
   @behaviour Pleroma.Web.ActivityPub.MRF.Policy
 
+  @impl true
+  def history_awareness, do: :manual
+
   defp check_reject(message, hashtags) do
     if Enum.any?(Config.get([:mrf_hashtag, :reject]), fn match -> match in hashtags end) do
       {:reject, "[HashtagPolicy] Matches with rejected keyword"}
@@ -47,22 +50,46 @@ defmodule Pleroma.Web.ActivityPub.MRF.HashtagPolicy do
 
   defp check_ftl_removal(message, _hashtags), do: {:ok, message}
 
-  defp check_sensitive(message, hashtags) do
-    if Enum.any?(Config.get([:mrf_hashtag, :sensitive]), fn match -> match in hashtags end) do
-      {:ok, Kernel.put_in(message, ["object", "sensitive"], true)}
-    else
-      {:ok, message}
-    end
+  defp check_sensitive(message) do
+    {:ok, new_object} =
+      Object.Updater.do_with_history(message["object"], fn object ->
+        hashtags = Object.hashtags(%Object{data: object})
+
+        if Enum.any?(Config.get([:mrf_hashtag, :sensitive]), fn match -> match in hashtags end) do
+          {:ok, Map.put(object, "sensitive", true)}
+        else
+          {:ok, object}
+        end
+      end)
+
+    {:ok, Map.put(message, "object", new_object)}
   end
 
   @impl true
-  def filter(%{"type" => "Create", "object" => object} = message) do
-    hashtags = Object.hashtags(%Object{data: object})
+  def filter(%{"type" => type, "object" => object} = message) when type in ["Create", "Update"] do
+    history_items =
+      with %{"formerRepresentations" => %{"orderedItems" => items}} <- object do
+        items
+      else
+        _ -> []
+      end
+
+    historical_hashtags =
+      Enum.reduce(history_items, [], fn item, acc ->
+        acc ++ Object.hashtags(%Object{data: item})
+      end)
+
+    hashtags = Object.hashtags(%Object{data: object}) ++ historical_hashtags
 
     if hashtags != [] do
       with {:ok, message} <- check_reject(message, hashtags),
-           {:ok, message} <- check_ftl_removal(message, hashtags),
-           {:ok, message} <- check_sensitive(message, hashtags) do
+           {:ok, message} <-
+             (if "type" == "Create" do
+                check_ftl_removal(message, hashtags)
+              else
+                {:ok, message}
+              end),
+           {:ok, message} <- check_sensitive(message) do
         {:ok, message}
       end
     else
diff --git a/test/pleroma/web/activity_pub/mrf/hashtag_policy_test.exs b/test/pleroma/web/activity_pub/mrf/hashtag_policy_test.exs
index 7f2d78a4c..32991c966 100644
--- a/test/pleroma/web/activity_pub/mrf/hashtag_policy_test.exs
+++ b/test/pleroma/web/activity_pub/mrf/hashtag_policy_test.exs
@@ -20,6 +20,76 @@ defmodule Pleroma.Web.ActivityPub.MRF.HashtagPolicyTest do
     assert modified["object"]["sensitive"]
   end
 
+  test "it is history-aware" do
+    activity = %{
+      "type" => "Create",
+      "object" => %{
+        "content" => "hey",
+        "tag" => []
+      }
+    }
+
+    activity_data =
+      activity
+      |> put_in(
+        ["object", "formerRepresentations"],
+        %{
+          "type" => "OrderedCollection",
+          "orderedItems" => [
+            Map.put(
+              activity["object"],
+              "tag",
+              [%{"type" => "Hashtag", "name" => "#nsfw"}]
+            )
+          ]
+        }
+      )
+
+    {:ok, modified} =
+      Pleroma.Web.ActivityPub.MRF.filter_one(
+        Pleroma.Web.ActivityPub.MRF.HashtagPolicy,
+        activity_data
+      )
+
+    refute modified["object"]["sensitive"]
+    assert Enum.at(modified["object"]["formerRepresentations"]["orderedItems"], 0)["sensitive"]
+  end
+
+  test "it works with Update" do
+    activity = %{
+      "type" => "Update",
+      "object" => %{
+        "content" => "hey",
+        "tag" => []
+      }
+    }
+
+    activity_data =
+      activity
+      |> put_in(
+        ["object", "formerRepresentations"],
+        %{
+          "type" => "OrderedCollection",
+          "orderedItems" => [
+            Map.put(
+              activity["object"],
+              "tag",
+              [%{"type" => "Hashtag", "name" => "#nsfw"}]
+            )
+          ]
+        }
+      )
+
+    {:ok, modified} =
+      Pleroma.Web.ActivityPub.MRF.filter_one(
+        Pleroma.Web.ActivityPub.MRF.HashtagPolicy,
+        activity_data
+      )
+
+    refute modified["object"]["sensitive"]
+    assert Enum.at(modified["object"]["formerRepresentations"]["orderedItems"], 0)["sensitive"]
+  end
+
   test "it doesn't sets the sensitive property with irrelevant hashtags" do
     user = insert(:user)