FEATURE: digest emails will try to choose topics from your tracked and watched categories first

app/models/topic.rb

@@ -325,6 +325,7 @@ class Topic < ActiveRecord::Base
               .visible
               .secured(Guardian.new(user))
               .joins("LEFT OUTER JOIN topic_users ON topic_users.topic_id = topics.id AND topic_users.user_id = #{user.id.to_i}")
+              .joins("LEFT OUTER JOIN category_users ON category_users.category_id = topics.category_id AND category_users.user_id = #{user.id.to_i}")
               .joins("LEFT OUTER JOIN users ON users.id = topics.user_id")
               .where(closed: false, archived: false)
               .where("COALESCE(topic_users.notification_level, 1) <> ?", TopicUser.notification_levels[:muted])
@@ -338,7 +339,7 @@ class Topic < ActiveRecord::Base
 
     if !!opts[:top_order]
       topics = topics.joins("LEFT OUTER JOIN top_topics ON top_topics.topic_id = topics.id")
-                     .order(TopicQuerySQL.order_top_for(score))
+                     .order(TopicQuerySQL.order_top_with_notification_levels(score))
     end
 
     if opts[:limit]

lib/topic_query_sql.rb

@@ -51,5 +51,9 @@ module TopicQuerySQL
        topics.bumped_at DESC"
     end
 
+    def order_top_with_notification_levels(score)
+      "COALESCE(category_users.notification_level, 1) DESC, COALESCE(top_topics.#{score}, 0) DESC, topics.bumped_at DESC"
+    end
+
   end
 end

spec/models/topic_spec.rb

@@ -1382,6 +1382,16 @@ describe Topic do
       expect(Topic.for_digest(user, 1.year.ago, top_order: true)).to eq([topic])
     end
 
+    it "sorts by category notification levels" do
+      category1, category2 = Fabricate(:category), Fabricate(:category)
+      2.times {|i| Fabricate(:topic, category: category1) }
+      topic1 = Fabricate(:topic, category: category2)
+      2.times {|i| Fabricate(:topic, category: category1) }
+      CategoryUser.create(user: user, category: category2, notification_level: CategoryUser.notification_levels[:watching])
+      for_digest = Topic.for_digest(user, 1.year.ago, top_order: true)
+      expect(for_digest.first).to eq(topic1)
+    end
+
   end
 
   describe 'secured' do