default tag listing now weighted by time

app/models/tag.rb

@@ -117,9 +117,6 @@ class Tag < ActiveRecord::Base
   end
 
   module StatisticsMethods
-    def trending
-      raise NotImplementedError
-    end
   end
 
   module NameMethods

app/presenters/post_set_presenters/post.rb

@@ -23,16 +23,25 @@ module PostSetPresenters
     end
 
     def popular_tags
-      n = 1
-      results = []
+      Cache.get("popular-tags", 1.hour) do
+        CurrentUser.scoped(User.admins.first, "127.0.0.1") do
+          n = 1
+          results = []
 
-      while results.empty? && n < 256
-        query = n.days.ago.strftime("date:>%Y-%m-%d")
-        results = RelatedTagCalculator.calculate_from_sample_to_array(query).map(&:first)
-        n *= 2
+          while results.empty? && n < 256
+            query = n.days.ago.strftime("date:>%Y-%m-%d")
+            results = RelatedTagCalculator.calculate_from_sample_to_array(query)
+            n *= 2
+          end
+
+          results.map! do |tag_name, recent_count|
+            tag = Tag.find_or_create_by_name(tag_name)
+            [tag_name, recent_count.to_f / tag.post_count.to_f]
+          end
+
+          results.sort_by! {|x| -x[1]}.map(&:first)
+        end
       end
-
-      results
     end
 
     def pattern_tags