From f5d9ea4357f1d4f433927c448c714f50e8701a17 Mon Sep 17 00:00:00 2001
From: kikito <kikito@gmail.com>
Date: Wed, 28 Oct 2015 16:25:35 +0100
Subject: [PATCH] adds confidence_score capacity to the comment model

---
 app/models/comment.rb       |  8 ++++++++
 spec/factories.rb           |  4 ++++
 spec/models/comment_spec.rb | 38 +++++++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/app/models/comment.rb b/app/models/comment.rb
index e9bb59775..6fdf4d294 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -17,10 +17,13 @@ class Comment < ActiveRecord::Base
   belongs_to :commentable, -> { with_hidden }, polymorphic: true, counter_cache: true
   belongs_to :user, -> { with_hidden }
 
+  before_save :calculate_confidence_score
+
   scope :recent, -> { order(id: :desc) }
   scope :for_render, -> { with_hidden.includes(user: :organization) }
   scope :with_visible_author, -> { joins(:user).where("users.hidden_at IS NULL") }
   scope :sort_by_flags, -> { order(flags_count: :desc, updated_at: :desc) }
+  scope :sort_by_confidence_score , -> { order(confidence_score: :desc) }
   scope :sort_by_created_at, -> { order(created_at: :desc) }
 
   after_create :call_after_commented
@@ -88,6 +91,11 @@ class Comment < ActiveRecord::Base
     1000
   end
 
+  def calculate_confidence_score
+    self.confidence_score = ScoreCalculator.confidence_score(cached_votes_total,
+                                                             cached_votes_up)
+  end
+
   private
 
     def validate_body_length
diff --git a/spec/factories.rb b/spec/factories.rb
index eff656edf..ddbb1d072 100644
--- a/spec/factories.rb
+++ b/spec/factories.rb
@@ -216,6 +216,10 @@ FactoryGirl.define do
         Flag.flag(FactoryGirl.create(:user), debate)
       end
     end
+
+    trait :with_confidence_score do
+      before(:save) { |d| d.calculate_confidence_score }
+    end
   end
 
   factory :administrator do
diff --git a/spec/models/comment_spec.rb b/spec/models/comment_spec.rb
index 6d37eb71b..636bf21a4 100644
--- a/spec/models/comment_spec.rb
+++ b/spec/models/comment_spec.rb
@@ -39,6 +39,44 @@ describe Comment do
     end
   end
 
+  describe "#confidence_score" do
+
+    it "takes into account percentage of total votes and total_positive and total negative votes" do
+      comment = create(:comment, :with_confidence_score, cached_votes_up: 100, cached_votes_total: 100)
+      expect(comment.confidence_score).to eq(10000)
+
+      comment = create(:comment, :with_confidence_score, cached_votes_up: 0, cached_votes_total: 100)
+      expect(comment.confidence_score).to eq(0)
+
+      comment = create(:comment, :with_confidence_score, cached_votes_up: 75, cached_votes_total: 100)
+      expect(comment.confidence_score).to eq(3750)
+
+      comment = create(:comment, :with_confidence_score, cached_votes_up: 750, cached_votes_total: 1000)
+      expect(comment.confidence_score).to eq(37500)
+
+      comment = create(:comment, :with_confidence_score, cached_votes_up: 10, cached_votes_total: 100)
+      expect(comment.confidence_score).to eq(-800)
+    end
+
+    describe 'actions which affect it' do
+      let(:comment) { create(:comment, :with_confidence_score) }
+
+      it "increases with like" do
+        previous = comment.confidence_score
+        5.times { comment.vote_by(voter: create(:user), vote: true) }
+        expect(previous).to be < comment.confidence_score
+      end
+
+      it "decreases with dislikes" do
+        comment.vote_by(voter: create(:user), vote: true)
+        previous = comment.confidence_score
+        3.times { comment.vote_by(voter: create(:user), vote: false) }
+        expect(previous).to be > comment.confidence_score
+      end
+    end
+
+  end
+
   describe "cache" do
     let(:comment) { create(:comment) }