Sort group scores correctly in backend

app/serializers/group_serializer.rb

@@ -2,7 +2,17 @@
 
 class GroupSerializer < ApplicationSerializer
   attributes :number
+  attributes :group_scores
 
   has_many :matches
-  has_many :group_scores
+
+  def group_scores
+    sorted_group_scores = object.group_scores.sort_by do |x|
+      # sort sorts from smallest to largest, therefore we need to negate the values
+      [
+        -x.group_points, -(x.scored_points - x.received_points), -x.scored_points
+      ]
+    end
+    sorted_group_scores.map { |group_score| GroupScoreSerializer.new(group_score) }
+  end
 end