MRF: simple policy: refactor module to use guards and pattern matching

lib/pleroma/web/activity_pub/mrf/simple_policy.ex

@@ -5,86 +5,77 @@ defmodule Pleroma.Web.ActivityPub.MRF.SimplePolicy do
   @mrf_policy Application.get_env(:pleroma, :mrf_simple)
 
   @accept Keyword.get(@mrf_policy, :accept)
-  defp check_accept(actor_info, object) do
-    if length(@accept) > 0 and not (actor_info.host in @accept) do
-      {:reject, nil}
-    else
-      {:ok, object}
-    end
+  defp check_accept(%{host: actor_host} = actor_info, object)
+       when length(@accept) > 0 and not (actor_host in @accept) do
+    {:reject, nil}
   end
 
+  defp check_accept(actor_info, object), do: {:ok, object}
+
   @reject Keyword.get(@mrf_policy, :reject)
-  defp check_reject(actor_info, object) do
-    if actor_info.host in @reject do
-      {:reject, nil}
-    else
-      {:ok, object}
-    end
+  defp check_reject(%{host: actor_host} = actor_info, object) when actor_host in @reject do
+    {:reject, nil}
   end
 
+  defp check_reject(actor_info, object), do: {:ok, object}
+
   @media_removal Keyword.get(@mrf_policy, :media_removal)
-  defp check_media_removal(actor_info, %{"type" => activity_type} = object)
-       when activity_type == "Create" do
-    if actor_info.host in @media_removal do
-      child_object = Map.delete(object["object"], "attachment")
-      object = Map.put(object, "object", child_object)
-      {:ok, object}
-    else
-      {:ok, object}
-    end
+  defp check_media_removal(%{host: actor_host} = actor_info, %{"type" => "Create"} = object)
+       when actor_host in @media_removal do
+    child_object = Map.delete(object["object"], "attachment")
+    object = Map.put(object, "object", child_object)
+    {:ok, object}
   end
 
   defp check_media_removal(actor_info, object), do: {:ok, object}
 
   @media_nsfw Keyword.get(@mrf_policy, :media_nsfw)
-  defp check_media_nsfw(actor_info, %{"type" => activity_type} = object)
-       when activity_type == "Create" do
-    child_object = object["object"]
-
-    if actor_info.host in @media_nsfw and child_object["attachment"] != nil and
-         length(child_object["attachment"]) > 0 do
-      tags = (child_object["tag"] || []) ++ ["nsfw"]
-      child_object = Map.put(child_object, "tags", tags)
-      child_object = Map.put(child_object, "sensitive", true)
-      object = Map.put(object, "object", child_object)
-      {:ok, object}
-    else
-      {:ok, object}
-    end
+  defp check_media_nsfw(
+         %{host: actor_host} = actor_info,
+         %{
+           "type" => "Create",
+           "object" => %{"attachment" => child_attachment} = child_object
+         } = object
+       )
+       when actor_host in @media_nsfw and length(child_attachment) > 0 do
+    tags = (child_object["tag"] || []) ++ ["nsfw"]
+    child_object = Map.put(child_object, "tags", tags)
+    child_object = Map.put(child_object, "sensitive", true)
+    object = Map.put(object, "object", child_object)
+    {:ok, object}
   end
 
   defp check_media_nsfw(actor_info, object), do: {:ok, object}
 
   @ftl_removal Keyword.get(@mrf_policy, :federated_timeline_removal)
-  defp check_ftl_removal(actor_info, object) do
-    if actor_info.host in @ftl_removal do
-      user = User.get_by_ap_id(object["actor"])
+  defp check_ftl_removal(%{host: actor_host} = actor_info, object)
+       when actor_host in @ftl_removal do
+    user = User.get_by_ap_id(object["actor"])
 
-      # flip to/cc relationship to make the post unlisted
-      object =
-        if "https://www.w3.org/ns/activitystreams#Public" in object["to"] and
-             user.follower_address in object["cc"] do
-          to =
-            List.delete(object["to"], "https://www.w3.org/ns/activitystreams#Public") ++
-              [user.follower_address]
+    # flip to/cc relationship to make the post unlisted
+    object =
+      if "https://www.w3.org/ns/activitystreams#Public" in object["to"] and
+           user.follower_address in object["cc"] do
+        to =
+          List.delete(object["to"], "https://www.w3.org/ns/activitystreams#Public") ++
+            [user.follower_address]
 
-          cc =
-            List.delete(object["cc"], user.follower_address) ++
-              ["https://www.w3.org/ns/activitystreams#Public"]
+        cc =
+          List.delete(object["cc"], user.follower_address) ++
+            ["https://www.w3.org/ns/activitystreams#Public"]
 
-          object
-          |> Map.put("to", to)
-          |> Map.put("cc", cc)
-        else
-          object
-        end
+        object
+        |> Map.put("to", to)
+        |> Map.put("cc", cc)
+      else
+        object
+      end
 
-      {:ok, object}
-    else
-      {:ok, object}
-    end
+    {:ok, object}
   end
 
+  defp check_ftl_removal(actor_info, object), do: {:ok, object}
+
   @impl true
   def filter(object) do
     actor_info = URI.parse(object["actor"])