Use serializer to group environments into folders

app/serializers/environment_serializer.rb

 class EnvironmentSerializer < BaseSerializer
+  Struct.new('Item', :name, :size, :id, :latest)
+
   entity EnvironmentEntity
+
+  def with_folders
+    tap { @itemize = true }
+  end
+
+  def itemized?
+    @itemize
+  end
+
+  def represent(resource, opts = {})
+    # resource = 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))
+
+    items.zip(environments).map do |item|
+      Struct::Item.new(*item.flatten)
+    end
+  end
 end