Add route to get object like activities

lib/pleroma/web/activity_pub/views/object_view.ex

@@ -35,4 +35,38 @@ defmodule Pleroma.Web.ActivityPub.ObjectView do
 
     Map.merge(base, additional)
   end
+
+  def render("likes.json", ap_id, likes, page) do
+    collection(likes, "#{ap_id}/likes", page)
+    |> Map.merge(Pleroma.Web.ActivityPub.Utils.make_json_ld_header())
+  end
+
+  def render("likes.json", ap_id, likes) do
+    %{
+      "id" => "#{ap_id}/likes",
+      "type" => "OrderedCollection",
+      "totalItems" => length(likes),
+      "first" => collection(likes, "#{ap_id}/followers", 1)
+    }
+    |> Map.merge(Pleroma.Web.ActivityPub.Utils.make_json_ld_header())
+  end
+
+  def collection(collection, iri, page) do
+    offset = (page - 1) * 10
+    items = Enum.slice(collection, offset, 10)
+    items = Enum.map(items, fn object -> Transmogrifier.prepare_object(object.data) end)
+    total = length(collection)
+
+    map = %{
+      "id" => "#{iri}?page=#{page}",
+      "type" => "OrderedCollectionPage",
+      "partOf" => iri,
+      "totalItems" => total,
+      "orderedItems" => items
+    }
+
+    if offset < total do
+      Map.put(map, "next", "#{iri}?page=#{page + 1}")
+    end
+  end
 end