Merge pull request #42 from turniere/ticket/TURNIERE-183

Implement statistics endpoint

app/controllers/statistics_controller.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+class StatisticsController < ApplicationController
+  before_action :set_tournament, only: %i[index]
+
+  # GET /tournaments/1/statistics
+  def index
+    group_stage = @tournament.stages.find_by(level: -1)
+    if group_stage
+      service = StatisticsService.new group_stage
+      render json: {
+        most_dominant_score: service.most_dominant_score,
+        least_dominant_score: service.least_dominant_score,
+        group_scores: service.group_scores
+      }
+    else
+      render json: {}, status: :not_implemented
+    end
+  end
+
+  private
+
+  def set_tournament
+    @tournament = Tournament.find(params[:tournament_id])
+  end
+end

app/models/stage.rb

@@ -8,8 +8,12 @@ class Stage < ApplicationRecord
   delegate :owner, to: :tournament
 
   def teams
-    return matches.map(&:teams).flatten.uniq unless matches.size.zero?
-
-    groups.map(&:teams).flatten.uniq unless groups.size.zero?
+    if !matches.size.zero?
+      matches.map(&:teams).flatten.uniq
+    elsif !groups.size.zero?
+      groups.map(&:teams).flatten.uniq
+    else
+      []
+    end
   end
 end

app/services/statistics_service.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+class StatisticsService
+  def initialize(stage)
+    raise 'Unsupported stage type' if stage.nil? || stage.groups.empty?
+
+    @stage = stage
+  end
+
+  def group_scores
+    sort_group_scores(@stage.groups, :group_points)
+  end
+
+  def most_dominant_score
+    sort_group_scores(@stage.groups, :scored_points).first
+  end
+
+  def least_dominant_score
+    sort_group_scores(@stage.groups, :received_points).first
+  end
+
+  private
+
+  # Sort group scores associated with `groups` by GroupScore#`attr`
+  # in descending order
+  #
+  # @param groups [Array] Groups to take GroupScore objects from
+  # @param attr [Symbol] GroupScore attribute to sort by
+  # @return [Array] Sorted array of group scores
+  def sort_group_scores(groups, attr)
+    groups
+      .map(&:group_scores).flatten # collect all group scores
+      .sort_by(&attr).reverse
+  end
+end

config/routes.rb

@@ -8,6 +8,8 @@ Rails.application.routes.draw do
 
   resources :matches, only: %i[show update]
   resources :teams, only: %i[show update]
-  resources :tournaments
+  resources :tournaments do
+    resources :statistics, only: %i[index]
+  end
   resources :match_scores, only: %i[show update]
 end

spec/controllers/statistics_controller_spec.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe StatisticsController, type: :controller do
+  describe 'GET #index' do
+    context 'tournament without a group stage' do
+      it 'returns a not implemented response' do
+        get :index, params: { tournament_id: create(:tournament).to_param }
+        expect(response).to have_http_status(:not_implemented)
+      end
+    end
+
+    context 'tournament with a group stage' do
+      before do
+        @tournament = create(:group_stage_tournament)
+        @group_stage = @tournament.stages.find_by(level: -1)
+        @most_dominant_score = create(:group_score,
+                                      team: @tournament.teams.first,
+                                      group_points: 100,
+                                      scored_points: 100, received_points: 0)
+        @least_dominant_score = create(:group_score,
+                                       team: @tournament.teams.first,
+                                       group_points: 0,
+                                       scored_points: 0, received_points: 100)
+        @tournament.stages.first.groups.first.group_scores << @most_dominant_score
+        @tournament.stages.first.groups.first.group_scores << @least_dominant_score
+        @tournament.save!
+      end
+
+      it 'returns a success response' do
+        get :index, params: { tournament_id: @tournament.to_param }
+        expect(response).to be_successful
+      end
+
+      it 'returns a list containing all group scores' do
+        get :index, params: { tournament_id: @tournament.to_param }
+        expect(deserialize_response(response)[:group_scores].length).to eq(GroupScore.count)
+      end
+
+      it 'returns a most dominant group score' do
+        get :index, params: { tournament_id: @tournament.to_param }
+        expect(deserialize_response(response)[:most_dominant_score][:id]).to eq(@most_dominant_score.id)
+      end
+
+      it 'returns a least dominant group score' do
+        get :index, params: { tournament_id: @tournament.to_param }
+        expect(deserialize_response(response)[:least_dominant_score][:id]).to eq(@least_dominant_score.id)
+      end
+    end
+  end
+end

spec/routing/statistics_routing_spec.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe StatisticsController, type: :routing do
+  describe 'routing' do
+    it 'routes to #index' do
+      expect(get: '/tournaments/1/statistics').to route_to('statistics#index', tournament_id: '1')
+    end
+  end
+end

spec/services/statistics_service_spec.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+RSpec.describe StatisticsService do
+  before do
+    # build tournament with predictable test data
+    tournament = create(:tournament)
+    group_stage = create(:group_stage)
+    group = group_stage.groups.first
+    @most_dominant_score = create(:group_score,
+                                  group_points: 100,
+                                  scored_points: 100, received_points: 0)
+    @least_dominant_score = create(:group_score,
+                                   group_points: 0,
+                                   scored_points: 0, received_points: 100)
+    group.group_scores << @most_dominant_score
+    group.group_scores << @least_dominant_score
+    tournament.stages << group_stage
+    @service = StatisticsService.new group_stage
+  end
+
+  describe '#new' do
+    context 'with a playoff stage' do
+      it 'throws an exception' do
+        expect do
+          StatisticsService.new create(:playoff_stage)
+        end.to raise_error(RuntimeError)
+      end
+    end
+
+    context 'with a group stage' do
+      it 'succeeds' do
+        StatisticsService.new create(:group_stage)
+      end
+    end
+  end
+
+  describe '#most_dominant_score' do
+    it 'returns the most dominant group score' do
+      expect(@service.most_dominant_score.id).to eq(@most_dominant_score.id)
+    end
+  end
+
+  describe '#least_dominant_score' do
+    it 'returns the least dominant group score' do
+      expect(@service.least_dominant_score.id).to eq(@least_dominant_score.id)
+    end
+  end
+
+  describe '#group_scores' do
+    it 'returns an array containing all group scores' do
+      expect(@service.group_scores.length).to eq(GroupScore.count)
+    end
+  end
+end