Break down new topic counts by category if a digest contains many.

app/helpers/user_notifications_helper.rb

@@ -70,8 +70,15 @@ module UserNotificationsHelper
   end
 
 
-  def email_category(category)
-    return "" if category.blank? || category.uncategorized?
+  def email_category(category, opts=nil)
+    opts = opts || {}
+
+    # If there is no category, bail
+    return "" if category.blank?
+
+    # By default hide uncategorized
+    return "" if category.uncategorized? && !opts[:show_uncategorized]
+
     result = ""
     if category.parent_category.present?
       result << "<span style='background-color: ##{category.parent_category.color}; font-size: 12px; padding: 4px 2px; font-weight: bold; margin: 0; width: 2px;'>&nbsp;</span>"

app/mailers/user_notifications.rb

@@ -30,6 +30,7 @@ class UserNotifications < ActionMailer::Base
                  email_token: opts[:email_token])
   end
 
+
   def digest(user, opts={})
     @user = user
     @base_url = Discourse.base_url
@@ -41,19 +42,28 @@ class UserNotifications < ActionMailer::Base
     @last_seen_at = I18n.l(@user.last_seen_at || @user.created_at, format: :short)
 
     # A list of topics to show the user
-    @featured_topics = Topic.for_digest(user, min_date).to_a
+    @featured_topics = Topic.for_digest(user, min_date, limit: 20, top_order: true).to_a
 
     # Don't send email unless there is content in it
     if @featured_topics.present?
-      @new_topics_since_seen = Topic.listable_topics
-                                    .where("created_at > ?", min_date).count - @featured_topics.length
+      featured_topic_ids = @featured_topics.map(&:id)
+
+      @new_topics_since_seen = Topic.new_since_last_seen(user, min_date, featured_topic_ids).count
+      if @new_topics_since_seen > 1000
+        category_counts = Topic.new_since_last_seen(user, min_date, featured_topic_ids).group(:category_id).count
+
+        @new_by_category = []
+        if category_counts.present?
+          Category.where(id: category_counts.keys).each do |c|
+            @new_by_category << [c, category_counts[c.id]]
+          end
+          @new_by_category.sort_by! {|c| -c[1]}
+        end
+      end
 
-      @new_topics_since_seen = 0 if @new_topics_since_seen < 0
       @featured_topics, @new_topics = @featured_topics[0..4], @featured_topics[5..-1]
-
       @markdown_linker = MarkdownLinker.new(Discourse.base_url)
 
-
       build_email user.email,
                   from_alias: I18n.t('user_notifications.digest.from', site_name: SiteSetting.title),
                   subject: I18n.t('user_notifications.digest.subject_template',

app/models/topic.rb

@@ -260,21 +260,28 @@ class Topic < ActiveRecord::Base
   end
 
   # Returns hot topics since a date for display in email digest.
-  def self.for_digest(user, since)
+  def self.for_digest(user, since, opts=nil)
+    opts = opts || {}
     score = "#{ListController.best_period_for(since)}_score"
 
     topics = Topic
               .visible
               .secured(Guardian.new(user))
-              .joins("LEFT OUTER JOIN top_topics ON top_topics.topic_id = topics.id")
               .joins("LEFT OUTER JOIN topic_users ON topic_users.topic_id = topics.id AND topic_users.user_id = #{user.id.to_i}")
               .where(closed: false, archived: false)
               .where("COALESCE(topic_users.notification_level, 1) <> ?", TopicUser.notification_levels[:muted])
               .created_since(since)
               .listable_topics
               .includes(:category)
-              .order(TopicQuerySQL.order_top_for(score))
-              .limit(20)
+
+    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))
+    end
+
+    if opts[:limit]
+      topics = topics.limit(opts[:limit])
+    end
 
     # Remove category topics
     category_topic_ids = Category.pluck(:topic_id).compact!
@@ -291,6 +298,12 @@ class Topic < ActiveRecord::Base
     topics
   end
 
+  # Using the digest query, figure out what's  new for a user since last seen
+  def self.new_since_last_seen(user, since, featured_topic_ids)
+    topics = Topic.for_digest(user, since)
+    topics.where("topics.id NOT IN (?)", featured_topic_ids)
+  end
+
   def update_meta_data(data)
     self.meta_data = (self.meta_data || {}).merge(data.stringify_keys)
     save

app/views/user_notifications/digest.html.erb

@@ -45,7 +45,16 @@
     <%- end -%>
 
     <%- if @new_topics_since_seen > 0 %>
-      <p><%= t('user_notifications.digest.more_topics', last_seen_at: @last_seen_at, new_topics_since_seen: @new_topics_since_seen) %></p>
+      <%- if @new_by_category.present? %>
+        <p><%= t('user_notifications.digest.more_topics_category', last_seen_at: @last_seen_at, new_topics_since_seen: @new_topics_since_seen) %></p>
+        <div>
+        <%- @new_by_category.each do |c| %>
+          <span style="margin-bottom: 8px; margin-right: 10px; display: inline-block;"><%= email_category(c[0], show_uncategorized: true) %> x <%= c[1] %></span>
+        <%- end %>
+      </div>
+      <%- else %>
+        <p><%= t('user_notifications.digest.more_topics', last_seen_at: @last_seen_at, new_topics_since_seen: @new_topics_since_seen) %></p>
+      <%- end %>
     <%- end -%>
 
   <span class='footer-notice'>

config/locales/server.en.yml

@@ -1361,6 +1361,7 @@ en:
       from: "%{site_name} digest"
       read_more: "Read More"
       more_topics: "Also, since we last saw you on %{last_seen_at} there have been %{new_topics_since_seen} new topics posted."
+      more_topics_category: "Also, since we last saw you on %{last_seen_at} there have been %{new_topics_since_seen} new topics posted in the following categories:"
 
       posts:
         one: "1 post"

spec/mailers/user_notifications_spec.rb

@@ -52,6 +52,7 @@ describe UserNotifications do
     context "with new topics" do
       before do
         Topic.expects(:for_digest).returns([Fabricate(:topic, user: Fabricate(:coding_horror))])
+        Topic.expects(:new_since_last_seen).returns(Topic.none)
       end
 
       its(:to) { should == [user.email] }

spec/models/topic_spec.rb

@@ -1194,17 +1194,17 @@ describe Topic do
     let(:user) { Fabricate.build(:user) }
 
     it "returns none when there are no topics" do
-      Topic.for_digest(user, 1.year.ago).should be_blank
+      Topic.for_digest(user, 1.year.ago, top_order: true).should be_blank
     end
 
     it "doesn't return category topics" do
       Fabricate(:category)
-      Topic.for_digest(user, 1.year.ago).should be_blank
+      Topic.for_digest(user, 1.year.ago, top_order: true).should be_blank
     end
 
     it "returns regular topics" do
       topic = Fabricate(:topic)
-      Topic.for_digest(user, 1.year.ago).should == [topic]
+      Topic.for_digest(user, 1.year.ago, top_order: true).should == [topic]
     end
 
   end