From 57ef1d121101d785c043ef6aaf2d33bb9be3ec3b Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Mon, 24 Jan 2022 16:44:35 -0600
Subject: [PATCH] Add InlineQuotePolicy to force quote URLs inline

---
 config/config.exs                             |  2 +
 docs/configuration/cheatsheet.md              |  4 ++
 .../activity_pub/mrf/inline_quote_policy.ex   | 53 ++++++++++++++++++
 .../mrf/inline_quote_policy_test.exs          | 56 +++++++++++++++++++
 4 files changed, 115 insertions(+)
 create mode 100644 lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex
 create mode 100644 test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs

diff --git a/config/config.exs b/config/config.exs
index ebcbf8b49..56cc34db5 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -434,6 +434,8 @@ config :pleroma, :mrf_object_age,
 
 config :pleroma, :mrf_follow_bot, follower_nickname: nil
 
+config :pleroma, :mrf_inline_quote, prefix: "RT"
+
 config :pleroma, :rich_media,
   enabled: true,
   ignore_hosts: [],
diff --git a/docs/configuration/cheatsheet.md b/docs/configuration/cheatsheet.md
index f43cde114..32cc5811a 100644
--- a/docs/configuration/cheatsheet.md
+++ b/docs/configuration/cheatsheet.md
@@ -160,6 +160,7 @@ To add configuration to your config file, you can copy it from the base config.
     * `Pleroma.Web.ActivityPub.MRF.AntiFollowbotPolicy`: Drops follow requests from followbots. Users can still allow bots to follow them by first following the bot.
     * `Pleroma.Web.ActivityPub.MRF.KeywordPolicy`: Rejects or removes from the federated timeline or replaces keywords. (See [`:mrf_keyword`](#mrf_keyword)).
     * `Pleroma.Web.ActivityPub.MRF.ForceMentionsInContent`: Forces every mentioned user to be reflected in the post content.
+    * `Pleroma.Web.ActivityPub.MRF.InlineQuotePolicy`: Forces quote post URLs to be reflected in the message content inline.
 * `transparency`: Make the content of your Message Rewrite Facility settings public (via nodeinfo).
 * `transparency_exclusions`: Exclude specific instance names from MRF transparency.  The use of the exclusions feature will be disclosed in nodeinfo as a boolean value.
 
@@ -267,6 +268,9 @@ Notes:
 * `federated_timeline_removal_url`: A list of patterns which result in message with emojis whose URLs match being removed from federated timelines (a.k.a unlisted). This will apply only to statuses. Each pattern can be a string or a [regular expression](https://hexdocs.pm/elixir/Regex.html).
 * `federated_timeline_removal_shortcode`: A list of patterns which result in message with emojis whose shortcodes match being removed from federated timelines (a.k.a unlisted). This will apply only to statuses. Each pattern can be a string or a [regular expression](https://hexdocs.pm/elixir/Regex.html).
 
+#### :mrf_inline_quote
+* `prefix`: Prefix before the link (default: `RT`)
+
 ### :activitypub
 * `unfollow_blocked`: Whether blocks result in people getting unfollowed
 * `outgoing_blocks`: Whether to federate blocks to other instances
diff --git a/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex b/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex
new file mode 100644
index 000000000..0f1dc9f42
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex
@@ -0,0 +1,53 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.InlineQuotePolicy do
+  @moduledoc "Force a quote line into the message content."
+  @behaviour Pleroma.Web.ActivityPub.MRF.Policy
+
+  defp build_inline_quote(prefix, url) do
+    "<span class=\"quote-inline\"><br><br>#{prefix}: <a href=\"#{url}\">#{url}</a></span>"
+  end
+
+  defp filter_object(%{"quoteUrl" => quote_url} = object) do
+    content = object["content"] || ""
+
+    if content =~ quote_url do
+      object
+    else
+      prefix = Pleroma.Config.get([:mrf_inline_quote, :prefix])
+      content = content <> build_inline_quote(prefix, quote_url)
+      Map.put(object, "content", content)
+    end
+  end
+
+  @impl true
+  def filter(%{"object" => %{"quoteUrl" => _} = object} = activity) do
+    {:ok, Map.put(activity, "object", filter_object(object))}
+  end
+
+  @impl true
+  def filter(object), do: {:ok, object}
+
+  @impl true
+  def describe, do: {:ok, %{}}
+
+  @impl true
+  def config_description do
+    %{
+      key: :mrf_inline_quote,
+      related_policy: "Pleroma.Web.ActivityPub.MRF.InlineQuotePolicy",
+      label: "MRF Inline Quote",
+      description: "Force quote post URLs inline",
+      children: [
+        %{
+          key: :prefix,
+          type: :string,
+          description: "Prefix before the link",
+          suggestions: ["RT", "QT", "RE", "RN"]
+        }
+      ]
+    }
+  end
+end
diff --git a/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs b/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs
new file mode 100644
index 000000000..81dc06dda
--- /dev/null
+++ b/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs
@@ -0,0 +1,56 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.InlineQuotePolicyTest do
+  alias Pleroma.Web.ActivityPub.MRF.InlineQuotePolicy
+  use Pleroma.DataCase
+
+  test "adds quote URL to post content" do
+    quote_url = "https://gleasonator.com/objects/1234"
+
+    activity = %{
+      "type" => "Create",
+      "actor" => "https://gleasonator.com/users/alex",
+      "object" => %{
+        "type" => "Note",
+        "content" => "<p>Nice post</p>",
+        "quoteUrl" => quote_url
+      }
+    }
+
+    {:ok, %{"object" => %{"content" => filtered}}} = InlineQuotePolicy.filter(activity)
+
+    assert filtered ==
+             "<p>Nice post</p><span class=\"quote-inline\"><br><br>RT: <a href=\"https://gleasonator.com/objects/1234\">https://gleasonator.com/objects/1234</a></span>"
+  end
+
+  test "ignores Misskey quote posts" do
+    object = File.read!("test/fixtures/quote_post/misskey_quote_post.json") |> Jason.decode!()
+
+    activity = %{
+      "type" => "Create",
+      "actor" => "https://misskey.io/users/7rkrarq81i",
+      "object" => object
+    }
+
+    {:ok, filtered} = InlineQuotePolicy.filter(activity)
+    assert filtered == activity
+  end
+
+  test "ignores Fedibird quote posts" do
+    object = File.read!("test/fixtures/quote_post/fedibird_quote_post.json") |> Jason.decode!()
+
+    # Normally the ObjectValidator will fix this before it reaches MRF
+    object = Map.put(object, "quoteUrl", object["quoteURL"])
+
+    activity = %{
+      "type" => "Create",
+      "actor" => "https://fedibird.com/users/noellabo",
+      "object" => object
+    }
+
+    {:ok, filtered} = InlineQuotePolicy.filter(activity)
+    assert filtered == activity
+  end
+end