From 31c7a43a18e72d0d7fd4285ee539543dbfc7b4bc Mon Sep 17 00:00:00 2001
From: Petko Bordjukov <bordjukov@gmail.com>
Date: Mon, 10 Oct 2016 21:28:23 +0300
Subject: [PATCH] Add a Summary and Ranking

---
 app/controllers/summaries_controller.rb | 11 ++++++
 app/models/ranking.rb                   | 45 +++++++++++++++++++++++++
 app/models/summary.rb                   | 15 +++++++++
 app/views/summaries/show.json.jbuilder  |  1 +
 config/routes.rb                        |  1 +
 5 files changed, 73 insertions(+)
 create mode 100644 app/controllers/summaries_controller.rb
 create mode 100644 app/models/ranking.rb
 create mode 100644 app/models/summary.rb
 create mode 100644 app/views/summaries/show.json.jbuilder

diff --git a/app/controllers/summaries_controller.rb b/app/controllers/summaries_controller.rb
new file mode 100644
index 0000000..1a005e2
--- /dev/null
+++ b/app/controllers/summaries_controller.rb
@@ -0,0 +1,11 @@
+class SummariesController < ApplicationController
+  def show
+    @summary = Summary.new summary_params
+  end
+
+  private
+
+  def summary_params
+    params.require(:summary).permit(talk_ids: [])
+  end
+end
diff --git a/app/models/ranking.rb b/app/models/ranking.rb
new file mode 100644
index 0000000..e265285
--- /dev/null
+++ b/app/models/ranking.rb
@@ -0,0 +1,45 @@
+RankingEntry = Struct.new :talk_id, :votes, :place
+
+class Ranking
+  include ActiveModel::Model
+
+  attr_accessor :talk_ids
+
+  def ranking
+    @ranking ||= ranking_data.map do |talk_id, votes, place|
+      RankingEntry.new talk_id, votes, place
+    end
+  end
+
+  def [](talk_id)
+    ranking[talk_id]
+  end
+
+  def talk_ids
+    @talk_ids ||= []
+  end
+
+  private
+
+  def ranking_data
+    vote_data.sort_by { |_, votes| -votes }
+             .group_by { |_, votes| votes }
+             .each_with_index.map do |votes, placement|
+               votes.last.map {|talk_vote_data| talk_vote_data << placement + 1 }
+             end.flatten(1)
+  end
+
+  def vote_data
+    blank_vote_data.merge(database_vote_data)
+  end
+
+  def blank_vote_data
+    talk_ids.map do |talk_id|
+      [talk_id, 0]
+    end.to_h
+  end
+
+  def database_vote_data
+    SelectedTalk.group(:talk_id).where(talk_id: @talk_ids).count
+  end
+end
diff --git a/app/models/summary.rb b/app/models/summary.rb
new file mode 100644
index 0000000..d38bb7d
--- /dev/null
+++ b/app/models/summary.rb
@@ -0,0 +1,15 @@
+class Summary
+  include ActiveModel::Model
+
+  attr_accessor :talk_ids
+
+  def number_of_ballots
+    @number_of_ballots ||= TalkPreference.joins(:selected_talks)
+                                         .where(selected_talks: {talk_id: @talk_ids})
+                                         .uniq.count
+  end
+
+  def ranking
+    @ranking ||= Ranking.new(talk_ids: talk_ids).ranking
+  end
+end
diff --git a/app/views/summaries/show.json.jbuilder b/app/views/summaries/show.json.jbuilder
new file mode 100644
index 0000000..3b996b8
--- /dev/null
+++ b/app/views/summaries/show.json.jbuilder
@@ -0,0 +1 @@
+json.extract! @summary, :number_of_ballots, :ranking
diff --git a/config/routes.rb b/config/routes.rb
index 3dd5b2e..b3b5bf3 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,5 +1,6 @@
 Rails.application.routes.draw do
   resources :talk_preferences, only: [:index, :show, :create, :update]
   root to: 'home#index'
+  resource :summary, only: :show
   # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
 end