Add option to return activity from object fetch, don't unnecessarily synthesize Create if one already exists

lib/clacks/object.ex

@@ -24,6 +24,17 @@ defmodule Clacks.Object do
     changeset(%__MODULE__{}, %{data: data})
   end
 
+  @spec get_actor(object :: t()) :: Clacks.Actor.t() | nil
+  def get_actor(object) do
+    case object.data["actor"] || object.data["attributedTo"] do
+      nil ->
+        nil
+
+      id when is_binary(id) ->
+        Clacks.Actor.get_by_ap_id(id)
+    end
+  end
+
   @spec get_by_ap_id(
           ap_id :: String.t(),
           force_refetch :: boolean(),
@@ -42,8 +53,9 @@ defmodule Clacks.Object do
     Repo.one(from o in __MODULE__, where: fragment("?->>'id'", o.data) == ^ap_id)
   end
 
-  @spec fetch(ap_id :: String.t(), synthesize_create :: boolean()) :: t() | nil
+  @spec fetch(ap_id :: String.t(), synthesize_create :: boolean(), return :: :object | :activity) ::
-  def fetch(ap_id, synthesize_create \\ true) do
+          t() | nil
+  def fetch(ap_id, synthesize_create \\ true, return \\ :object) do
     case Clacks.ActivityPub.Fetcher.fetch_object(ap_id) do
       nil ->
         nil
@@ -61,21 +73,34 @@ defmodule Clacks.Object do
             actor = data["actor"] || data["attributedTo"]
             _ = Clacks.Actor.get_by_ap_id(actor)
 
-            if synthesize_create do
+            activity =
-              create = Clacks.ActivityPub.synthesized_create(data)
+              case Clacks.Activity.get_by_object_ap_id(ap_id) do
+                nil ->
+                  if synthesize_create do
+                    create = Clacks.ActivityPub.synthesized_create(data)
 
-              changeset =
+                    changeset =
-                Clacks.Activity.changeset(%Clacks.Activity{}, %{
+                      Clacks.Activity.changeset(%Clacks.Activity{}, %{
-                  data: create,
+                        data: create,
-                  local: false,
+                        local: false,
-                  actor: actor
+                        actor: actor
-                })
+                      })
 
-              {:ok, _create} = Repo.insert_or_update(changeset)
+                    {:ok, create} = Repo.insert_or_update(changeset)
+                    create
+                  else
+                    nil
+                  end
+
+                %Clacks.Activity{} = activity ->
+                  activity
+              end
+
+            case return do
+              :object -> object
+              :activity -> activity
             end
 
-            object
-
           {:error, changeset} ->
             Logger.error("Couldn't store remote object #{ap_id}: #{inspect(changeset)}")
             nil