From 5193c9fd164be971b13f32462ac8f732e1a0c2a0 Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Mon, 18 Aug 2014 17:13:10 +1000
Subject: [PATCH] FIX: ensure consistency on topic featured users

---
 app/jobs/scheduled/ensure_db_consistency.rb |  1 +
 app/models/topic_featured_users.rb          | 44 +++++++++++++++++++++
 spec/models/topic_featured_users_spec.rb    | 31 +++++++++++++++
 3 files changed, 76 insertions(+)
 create mode 100644 spec/models/topic_featured_users_spec.rb

diff --git a/app/jobs/scheduled/ensure_db_consistency.rb b/app/jobs/scheduled/ensure_db_consistency.rb
index 83896fb27..bb1bb8e6b 100644
--- a/app/jobs/scheduled/ensure_db_consistency.rb
+++ b/app/jobs/scheduled/ensure_db_consistency.rb
@@ -8,6 +8,7 @@ module Jobs
       Group.refresh_automatic_groups!
       Notification.ensure_consistency!
       UserAction.ensure_consistency!
+      TopicFeaturedUsers.ensure_consistency!
       UserStat.update_view_counts(13.hours.ago)
     end
   end
diff --git a/app/models/topic_featured_users.rb b/app/models/topic_featured_users.rb
index 1efb4cd48..45771d28e 100644
--- a/app/models/topic_featured_users.rb
+++ b/app/models/topic_featured_users.rb
@@ -24,6 +24,50 @@ class TopicFeaturedUsers
      topic.featured_user4_id].uniq.compact
   end
 
+  def self.ensure_consistency!
+
+    sql = <<SQL
+
+WITH cte as (
+    SELECT
+        t.id, p.user_id,
+        ROW_NUMBER() OVER(PARTITION BY t.id ORDER BY COUNT(*) DESC) as rank
+    FROM topics t
+    JOIN posts p ON p.topic_id = t.id
+    WHERE p.deleted_at IS NULL AND NOT p.hidden AND p.user_id <> t.user_id AND
+          p.user_id <> t.last_post_user_id
+    GROUP BY t.id, p.user_id
+)
+
+UPDATE topics tt
+SET
+  featured_user1_id = featured_user1,
+  featured_user2_id = featured_user2,
+  featured_user3_id = featured_user3,
+  featured_user4_id = featured_user4
+FROM (
+  SELECT
+      c.id,
+      MAX(case when c.rank = 1 then c.user_id end) featured_user1,
+      MAX(case when c.rank = 2 then c.user_id end) featured_user2,
+      MAX(case when c.rank = 3 then c.user_id end) featured_user3,
+      MAX(case when c.rank = 4 then c.user_id end) featured_user4
+  FROM cte as c
+  WHERE c.rank <= 4
+  GROUP BY c.id
+) x
+WHERE x.id = tt.id AND
+(
+  COALESCE(featured_user1_id,-99) <> COALESCE(featured_user1,-99) OR
+  COALESCE(featured_user2_id,-99) <> COALESCE(featured_user2,-99) OR
+  COALESCE(featured_user3_id,-99) <> COALESCE(featured_user3,-99) OR
+  COALESCE(featured_user4_id,-99) <> COALESCE(featured_user4,-99)
+)
+SQL
+
+    Topic.exec_sql(sql)
+  end
+
   private
 
     def keys(args)
diff --git a/spec/models/topic_featured_users_spec.rb b/spec/models/topic_featured_users_spec.rb
new file mode 100644
index 000000000..2603d9650
--- /dev/null
+++ b/spec/models/topic_featured_users_spec.rb
@@ -0,0 +1,31 @@
+require 'spec_helper'
+
+describe TopicFeaturedUsers do
+  it 'ensures consistenct' do
+
+    t = Fabricate(:topic)
+    Fabricate(:post, topic_id: t.id, user_id: t.user_id)
+    p2 = Fabricate(:post, topic_id: t.id)
+    Fabricate(:post, topic_id: t.id, user_id: p2.user_id)
+    p4 = Fabricate(:post, topic_id: t.id)
+    p5 = Fabricate(:post, topic_id: t.id)
+
+    t.update_columns(featured_user1_id: 66,
+                     featured_user2_id: 70,
+                     featured_user3_id: 12,
+                     featured_user4_id: 7,
+                     last_post_user_id: p5.user_id
+                    )
+
+    TopicFeaturedUsers.ensure_consistency!
+
+    t.reload
+
+    t.featured_user1_id.should == p2.user_id
+    t.featured_user2_id.should == p4.user_id
+    t.featured_user3_id.should == nil
+    t.featured_user4_id.should == nil
+
+
+  end
+end