activitypub: transmogrifier: implement support for Listen activities

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -430,6 +430,36 @@ def handle_incoming(
     end
   end
 
+  def handle_incoming(
+        %{"type" => "Listen", "object" => %{"type" => "Audio"} = object} = data,
+        options
+      ) do
+    actor = Containment.get_actor(data)
+
+    data =
+      Map.put(data, "actor", actor)
+      |> fix_addressing
+
+    with {:ok, %User{} = user} <- User.get_or_fetch_by_ap_id(data["actor"]) do
+      options = Keyword.put(options, :depth, (options[:depth] || 0) + 1)
+      object = fix_object(object, options)
+
+      params = %{
+        to: data["to"],
+        object: object,
+        actor: user,
+        context: nil,
+        local: false,
+        published: data["published"],
+        additional: Map.take(data, ["cc", "id"])
+      }
+
+      ActivityPub.listen(params)
+    else
+      _e -> :error
+    end
+  end
+
   def handle_incoming(
         %{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data,
         _options
@@ -765,7 +795,8 @@ def prepare_object(object) do
   #  internal -> Mastodon
   #  """
 
-  def prepare_outgoing(%{"type" => "Create", "object" => object_id} = data) do
+  def prepare_outgoing(%{"type" => activity_type, "object" => object_id} = data)
+      when activity_type in ["Create", "Listen"] do
     object =
       object_id
       |> Object.normalize()

test/web/activity_pub/transmogrifier_test.exs

@@ -177,6 +177,35 @@ test "it works for incoming questions" do
              end)
     end
 
+    test "it works for incoming listens" do
+      data = %{
+        "@context" => "https://www.w3.org/ns/activitystreams",
+        "to" => ["https://www.w3.org/ns/activitystreams#Public"],
+        "cc" => [],
+        "type" => "Listen",
+        "id" => "http://mastodon.example.org/users/admin/listens/1234/activity",
+        "actor" => "http://mastodon.example.org/users/admin",
+        "object" => %{
+          "type" => "Audio",
+          "id" => "http://mastodon.example.org/users/admin/listens/1234",
+          "attributedTo" => "http://mastodon.example.org/users/admin",
+          "title" => "lain radio episode 1",
+          "artist" => "lain",
+          "album" => "lain radio",
+          "length" => 180_000
+        }
+      }
+
+      {:ok, %Activity{local: false} = activity} = Transmogrifier.handle_incoming(data)
+
+      object = Object.normalize(activity)
+
+      assert object.data["title"] == "lain radio episode 1"
+      assert object.data["artist"] == "lain"
+      assert object.data["album"] == "lain radio"
+      assert object.data["length"] == 180_000
+    end
+
     test "it rewrites Note votes to Answers and increments vote counters on question activities" do
       user = insert(:user)