From c6a0f8852016a27a964818587738184e789185fb Mon Sep 17 00:00:00 2001
From: kikito <kikito@gmail.com>
Date: Mon, 14 Sep 2015 16:29:01 +0200
Subject: [PATCH] implements a new hot scoring system

---
 app/models/debate.rb       | 24 ++++++++++--------------
 spec/models/debate_spec.rb |  8 ++++----
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/app/models/debate.rb b/app/models/debate.rb
index f1e9a621e..db3133877 100644
--- a/app/models/debate.rb
+++ b/app/models/debate.rb
@@ -113,23 +113,19 @@ class Debate < ActiveRecord::Base
   end
 
   def calculate_hot_score
-    z          = 1.96 # Normal distribution with a confidence of 0.95
-    time_unit  = 1.0 * 12.hours
-    start      = Time.new(2015, 6, 15)
+    start           = Time.new(2015, 6, 15)
     comments_weight = 1.0/20 # 1 positive vote / x comments
+    time_unit       = 12.hours.to_f
 
-    weighted_score = 0
+    total   = cached_votes_total + comments_weight * comments_count
+    ups     = cached_votes_up    + comments_weight * comments_count
+    downs   = total - ups
+    score   = ups - downs
+    order   = Math.log([score.abs, 1].max, 10)
+    sign    = (score <=> 0).to_f
+    seconds = ((created_at || Time.now) - start).to_f
 
-    n = cached_votes_total + comments_weight * comments_count
-    if n > 0 then
-      pos = cached_votes_up + comments_weight * comments_count
-      phat = 1.0 * pos / n
-      weighted_score = (phat + z*z/(2*n) - z * Math.sqrt((phat*(1-phat)+z*z/(4*n))/n))/(1+z*z/n)
-    end
-
-    age_in_units = 1.0 * ((created_at || Time.now) - start) / time_unit
-
-    self.hot_score = ((age_in_units**2 + weighted_score)*1000).round
+    self.hot_score = (((order * sign) + (seconds/time_unit)) * 1000000).round
   end
 
   def calculate_confidence_score
diff --git a/spec/models/debate_spec.rb b/spec/models/debate_spec.rb
index 377f933c8..f9af3c149 100644
--- a/spec/models/debate_spec.rb
+++ b/spec/models/debate_spec.rb
@@ -191,7 +191,7 @@ describe Debate do
     end
 
     it "increases for debates with more comments" do
-      more_comments = create(:debate, :with_hot_score, created_at: now, comments_count: 10)
+      more_comments = create(:debate, :with_hot_score, created_at: now, comments_count: 25)
       less_comments = create(:debate, :with_hot_score, created_at: now, comments_count: 1)
       expect(more_comments.hot_score).to be > less_comments.hot_score
     end
@@ -232,8 +232,8 @@ describe Debate do
 
       it "increases with comments" do
         previous = debate.hot_score
-        Comment.create(user: create(:user), commentable: debate, body: 'foo')
-        expect(previous).to be < debate.hot_score
+        25.times{ Comment.create(user: create(:user), commentable: debate, body: 'foobarbaz') }
+        expect(previous).to be < debate.reload.hot_score
       end
     end
   end
@@ -396,4 +396,4 @@ describe Debate do
 
   end
 
-end
\ No newline at end of file
+end