FEATURE: make top criteria formula multipliers controlled by site

setting

app/models/top_topic.rb

@@ -147,6 +147,15 @@ class TopTopic < ActiveRecord::Base
 
   def self.compute_top_score_for(period)
 
+    log_views_multiplier = SiteSetting.top_topics_formula_log_views_multiplier.to_f
+    log_views_multiplier = 2 if log_views_multiplier == 0
+
+    first_post_likes_multiplier = SiteSetting.top_topics_formula_first_post_likes_multiplier.to_f
+    first_post_likes_multiplier = 0.5 if first_post_likes_multiplier == 0
+
+    least_likes_per_post_multiplier = SiteSetting.top_topics_formula_least_likes_per_post_multiplier.to_f
+    least_likes_per_post_multiplier = 3 if least_likes_per_post_multiplier == 0
+
     if period == :all
       top_topics = "(
         SELECT t.like_count all_likes_count,
@@ -167,11 +176,11 @@ class TopTopic < ActiveRecord::Base
         WITH top AS (
           SELECT CASE
                    WHEN #{time_filter} THEN 0
-                   ELSE log(GREATEST(#{period}_views_count, 1)) * 2 +
-                        #{period}_op_likes_count * 0.5 +
+                   ELSE log(GREATEST(#{period}_views_count, 1)) * #{log_views_multiplier} +
+                        #{period}_op_likes_count * #{first_post_likes_multiplier} +
                         CASE WHEN #{period}_likes_count > 0 AND #{period}_posts_count > 0
                            THEN
-                            LEAST(#{period}_likes_count / #{period}_posts_count, 3)
+                            LEAST(#{period}_likes_count / #{period}_posts_count, #{least_likes_per_post_multiplier})
                            ELSE 0
                         END +
                         CASE WHEN topics.posts_count < 10 THEN

config/locales/server.en.yml

@@ -945,6 +945,10 @@ en:
     verbose_localization: "Show extended localization tips in the UI"
     previous_visit_timeout_hours: "How long a visit lasts before we consider it the 'previous' visit, in hours"
 
+    top_topics_formula_log_views_multiplier: "value of log views multiplier (n) in top topics formula: `log(views_count) * (n) + op_likes_count * 0.5 + LEAST(likes_count / posts_count, 3) + 10 + log(posts_count)`"
+    top_topics_formula_first_post_likes_multiplier: "value of first post likes multiplier (n) in top topics formula: `log(views_count) * 2 + op_likes_count * (n) + LEAST(likes_count / posts_count, 3) + 10 + log(posts_count)`"
+    top_topics_formula_least_likes_per_post_multiplier: "value of least likes per post multiplier (n) in top topics formula: `log(views_count) * 2 + op_likes_count * 0.5 + LEAST(likes_count / posts_count, (n)) + 10 + log(posts_count)`"
+
     rate_limit_create_topic: "After creating a topic, users must wait (n) seconds before creating another topic."
     rate_limit_create_post: "After posting, users must wait (n) seconds before creating another post."
     rate_limit_new_user_create_topic: "After creating a topic, new users must wait (n) seconds before creating another topic."

config/site_settings.yml

@@ -803,6 +803,15 @@ developer:
   verbose_localization:
     default: false
     client: true
+  top_topics_formula_log_views_multiplier:
+    default: 2
+    min: 0
+  top_topics_formula_first_post_likes_multiplier:
+    default: 0.5
+    min: 0
+  top_topics_formula_least_likes_per_post_multiplier:
+    default: 3
+    min: 0
   migrate_to_new_scheme:
     hidden: true
     default: false

spec/models/top_topic_spec.rb

@@ -38,9 +38,108 @@ describe TopTopic do
       it "should have top topics" do
         expect(TopTopic.pluck(:topic_id)).to match_array([t1.id, t2.id])
       end
-
     end
-
   end
 
+  describe "#compute_top_score_for" do
+
+    let(:user) { Fabricate(:user) }
+    let(:coding_horror) { Fabricate(:coding_horror) }
+
+    let!(:topic_1) { Fabricate(:topic, posts_count: 10, like_count: 28) }
+    let!(:t1_post_1) { Fabricate(:post, topic: topic_1, like_count: 28, post_number: 1)}
+
+    let!(:topic_2) { Fabricate(:topic, posts_count: 10, like_count: 20) }
+    let!(:t2_post_1) { Fabricate(:post, topic: topic_2, like_count: 10, post_number: 1) }
+    let!(:t2_post_2) { Fabricate(:post, topic: topic_2, like_count: 10) }
+
+    let!(:topic_3) { Fabricate(:topic, posts_count: 10) }
+    let!(:t3_post_1) { Fabricate(:post, topic_id: topic_3.id) }
+    let!(:t3_view_1) { TopicViewItem.add(topic_3.id, '127.0.0.1', user) }
+    let!(:t3_view_2) { TopicViewItem.add(topic_3.id, '127.0.0.2', coding_horror) }
+
+    # Note: all topics has 10 posts so we can skip "0 - ((10 - topics.posts_count) / 20) * #{period}_op_likes_count" calculation
+
+    it "should compute top score" do
+      # Default Formula: log(views_count) * {2} + op_likes_count * {0.5} + LEAST(likes_count / posts_count, {3}) + 10 + log(posts_count)
+      #
+      # topic_1 => 0 + 14 + 3 + 10 + 0 => 27
+      # topic_2 => 0 + 5 + 3 + 10 + 0.301029995664 => 18.301029995664
+      # topic_3 => 0.602059991328 + 0 + 0 + 10 + 0 => 10.602059991328
+
+      TopTopic.refresh!
+      top_topics = TopTopic.all
+
+      expect(top_topics.where(topic_id: topic_1.id).pluck(:yearly_score).first).to eq(27)
+      expect(top_topics.where(topic_id: topic_2.id).pluck(:yearly_score).first).to eq(18.301029995664)
+      expect(top_topics.where(topic_id: topic_3.id).pluck(:yearly_score).first).to eq(10.602059991328)
+
+      # when 'top_topics_formula_log_views_multiplier' setting is changed
+      SiteSetting.top_topics_formula_log_views_multiplier = 4
+      SiteSetting.top_topics_formula_first_post_likes_multiplier = 0.5 # unchanged
+      SiteSetting.top_topics_formula_least_likes_per_post_multiplier = 3 # unchanged
+
+      # New Formula: log(views_count) * {4} + op_likes_count * {0.5} + LEAST(likes_count / posts_count, {3}) + 10 + log(posts_count)
+      #
+      # topic_1 => 0 + 14 + 3 + 10 + 0 => 27
+      # topic_2 => 0 + 5 + 3 + 10 + 0.301029995664 => 18.301029995664
+      # topic_3 => 1.2041199826559 + 0 + 0 + 10 + 0 => 11.2041199826559
+
+      TopTopic.refresh!
+      top_topics = TopTopic.all
+
+      expect(top_topics.where(topic_id: topic_1.id).pluck(:yearly_score).first).to eq(27)
+      expect(top_topics.where(topic_id: topic_2.id).pluck(:yearly_score).first).to eq(18.301029995664)
+      expect(top_topics.where(topic_id: topic_3.id).pluck(:yearly_score).first).to eq(11.2041199826559)
+
+      # when 'top_topics_formula_first_post_likes_multiplier' setting is changed
+      SiteSetting.top_topics_formula_log_views_multiplier = 2 # unchanged
+      SiteSetting.top_topics_formula_first_post_likes_multiplier = 2
+      SiteSetting.top_topics_formula_least_likes_per_post_multiplier = 3 # unchanged
+
+      # New Formula: log(views_count) * {2} + op_likes_count * {2} + LEAST(likes_count / posts_count, {3}) + 10 + log(posts_count)
+      #
+      # topic_1 => 0 + 56 + 3 + 10 + 0 => 69
+      # topic_2 => 0 + 20 + 3 + 10 + 0.301029995664 => 33.301029995664
+      # topic_3 => 0.602059991328 + 0 + 0 + 10 + 0 => 10.602059991328
+
+      TopTopic.refresh!
+      top_topics = TopTopic.all
+
+      expect(top_topics.where(topic_id: topic_1.id).pluck(:yearly_score).first).to eq(69)
+      expect(top_topics.where(topic_id: topic_2.id).pluck(:yearly_score).first).to eq(33.301029995664)
+      expect(top_topics.where(topic_id: topic_3.id).pluck(:yearly_score).first).to eq(10.602059991328)
+
+      # when 'top_topics_formula_least_likes_per_post_multiplier' setting is changed
+      SiteSetting.top_topics_formula_log_views_multiplier = 2 # unchanged
+      SiteSetting.top_topics_formula_first_post_likes_multiplier = 0.5 # unchanged
+      SiteSetting.top_topics_formula_least_likes_per_post_multiplier = 6
+
+      # New Formula: log(views_count) * {2} + op_likes_count * {0.5} + LEAST(likes_count / posts_count, {6}) + 10 + log(posts_count)
+      #
+      # topic_1 => 0 + 14 + 6 + 10 + 0 => 30
+      # topic_2 => 0 + 5 + 6 + 10 + 0.301029995664 => 21.301029995664
+      # topic_3 => 0.602059991328 + 0 + 0 + 10 + 0 => 10.602059991328
+
+      TopTopic.refresh!
+      top_topics = TopTopic.all
+
+      expect(top_topics.where(topic_id: topic_1.id).pluck(:yearly_score).first).to eq(30)
+      expect(top_topics.where(topic_id: topic_2.id).pluck(:yearly_score).first).to eq(21.301029995664)
+      expect(top_topics.where(topic_id: topic_3.id).pluck(:yearly_score).first).to eq(10.602059991328)
+
+      # handles invalid string value
+      SiteSetting.top_topics_formula_log_views_multiplier = "not good"
+      SiteSetting.top_topics_formula_first_post_likes_multiplier = "not good"
+      SiteSetting.top_topics_formula_least_likes_per_post_multiplier = "not good"
+
+      TopTopic.refresh!
+      top_topics = TopTopic.all
+
+      expect(top_topics.where(topic_id: topic_1.id).pluck(:yearly_score).first).to eq(27)
+      expect(top_topics.where(topic_id: topic_2.id).pluck(:yearly_score).first).to eq(18.301029995664)
+      expect(top_topics.where(topic_id: topic_3.id).pluck(:yearly_score).first).to eq(10.602059991328)
+
+    end
+  end
 end