1 files changed, 47 insertions, 0 deletions
diff --git a/app/serializers/environment_serializer.rb b/app/serializers/environment_serializer.rb
index 91955542f25..fe16a3784c4 100644
--- a/app/serializers/environment_serializer.rb
+++ b/app/serializers/environment_serializer.rb
@@ -1,3 +1,50 @@
 class EnvironmentSerializer < BaseSerializer
+  Item = Struct.new(:name, :size, :latest)
+
   entity EnvironmentEntity
+
+  def within_folders
+    tap { @itemize = true }
+  end
+
+  def with_pagination(request, response)
+    tap { @paginator = Gitlab::Serializer::Pagination.new(request, response) }
+  end
+
+  def itemized?
+    @itemize
+  end
+
+  def paginated?
+    @paginator.present?
+  end
+
+  def represent(resource, opts = {})
+    resource = @paginator.paginate(resource) if paginated?
+
+    if itemized?
+      itemize(resource).map do |item|
+        { name: item.name,
+          size: item.size,
+          latest: super(item.latest, opts) }
+      end
+    else
+      super(resource, opts)
+    end
+  end
+
+  private
+
+  def itemize(resource)
+    items = resource.group(:item_name).order('item_name ASC')
+      .pluck('COALESCE(environment_type, name) AS item_name',
+             'COUNT(*) AS environments_count',
+             'MAX(id) AS last_environment_id')
+
+    environments = resource.where(id: items.map(&:last)).index_by(&:id)
+
+    items.map do |name, size, id|
+      Item.new(name, size, environments[id])
+    end
+  end
 end