Add InlineQuotePolicy to force quote URLs inline

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