Implement sorting correctly with <=> operator

app/models/group_score.rb

@@ -7,4 +7,17 @@ class GroupScore < ApplicationRecord
   def difference_in_points
     scored_points - received_points
   end
+
+  def <=>(other)
+    point_comparison = [-group_points, -difference_in_points, -scored_points] <=> [-other.group_points, -other.difference_in_points, -other.scored_points]
+    p point_comparison, team.name, other.team.name
+    if point_comparison.zero?
+      comparison_match = group.matches.find do |match|
+        match.match_scores.any? { |match_score| match_score.team == team }
+      end
+      comparison_match.scored_points_of(team) <=> comparison_match.scored_points_of(other.team)
+    else
+      point_comparison
+    end
+  end
 end

app/serializers/group_serializer.rb

@@ -7,12 +7,6 @@ class GroupSerializer < ApplicationSerializer
   has_many :matches
 
   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) }
+    object.group_scores.sort.map { |group_score| GroupScoreSerializer.new(group_score) }
   end
 end

app/services/group_stage_service.rb

@@ -93,17 +93,7 @@ class GroupStageService
     # @param group Group the group to get the teams from
     # @return [Array] of teams
     def teams_sorted_by_group_scores(group)
-      group.teams.sort do |a, b|
-        group_score_a = group.group_scores.find_by(team: a)
-        group_score_b = group.group_scores.find_by(team: b)
-
-        [group_score_b.group_points,
-         group_score_b.difference_in_points,
-         group_score_b.scored_points] <=>
-          [group_score_a.group_points,
-           group_score_a.difference_in_points,
-           group_score_a.scored_points]
-      end
+      group.group_scores.sort.map(&:team)
     end
 
     # Returns all teams advancing to playoff stage from given group stage