ActivityPub: Handle incoming announces.

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -73,6 +73,16 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
+  def handle_incoming(%{"type" => "Announce", "object" => object_id, "actor" => actor, "id" => id} = data) do
+    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
+         {:ok, object} <- ActivityPub.fetch_object_from_id(object_id),
+         {:ok, activity, object} <- ActivityPub.announce(actor, object, id, false) do
+      {:ok, activity}
+    else
+      _e -> :error
+    end
+  end
+
   # TODO
   # Accept
   # Undo

test/web/activity_pub/transmogrifier_test.exs

@@ -62,6 +62,17 @@ defmodule Pleroma.Web.ActivityPub.TransmogrifierTest do
       assert data["id"] == "http://mastodon.example.org/users/admin#likes/2"
       assert data["object"] == activity.data["object"]["id"]
     end
+
+    test "it works for incoming announces" do
+      data = File.read!("test/fixtures/mastodon-announce.json") |> Poison.decode!
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+      assert data["actor"] == "http://mastodon.example.org/users/admin"
+      assert data["type"] == "Announce"
+      assert data["id"] == "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
+      assert data["object"] == "http://mastodon.example.org/users/admin/statuses/99541947525187367"
+    end
   end
 
   describe "prepare outgoing" do