Use db schema for tags instead of plugin store and custom fields

lib/topic_query.rb

@@ -20,6 +20,7 @@ class TopicQuery
                      topic_ids
                      visible
                      category
+                     tags
                      order
                      ascending
                      no_subcategories
@@ -451,6 +452,20 @@ class TopicQuery
         result = result.references(:categories)
       end
 
+      # ALL TAGS: something like this?
+      # Topic.joins(:tags).where('tags.name in (?)', @options[:tags]).group('topic_id').having('count(*)=?', @options[:tags].size).select('topic_id')
+
+      if @options[:tags] && @options[:tags].size > 0
+        result = result.joins(:tags).preload(:tags)
+
+        # ANY of the given tags:
+        if @options[:tags][0].is_a?(Integer)
+          result = result.where("tags.id in (?)", @options[:tags])
+        else
+          result = result.where("tags.name in (?)", @options[:tags])
+        end
+      end
+
       result = apply_ordering(result, options)
       result = result.listable_topics.includes(:category)