FEATURE: query param for closed / archived / open

?status=closed for closed topics
?status=open for open topics
?status=archived for archived topics

app/controllers/list_controller.rb

@@ -156,6 +156,7 @@ def build_topic_list_options
       category: params[:category],
       sort_order: params[:sort_order],
       sort_descending: params[:sort_descending],
+      status: params[:status]
     }
     result[:no_subcategories] = true if params[:no_subcategories] == 'true'
     result

lib/topic_query.rb

@@ -18,7 +18,8 @@ class TopicQuery
                      category
                      sort_order
                      no_subcategories
-                     sort_descending).map(&:to_sym)
+                     sort_descending
+                     status).map(&:to_sym)
 
   # Maps `sort_order` to a columns in `topics`
   SORTABLE_MAPPING = {
@@ -243,6 +244,17 @@ def default_results(options={})
         result = result.where('topics.id in (?)', options[:topic_ids]).references(:topics)
       end
 
+      if status = options[:status]
+        case status
+        when 'open'
+          result = result.where('NOT topics.closed AND NOT topics.archived')
+        when 'closed'
+          result = result.where('topics.closed')
+        when 'archived'
+          result = result.where('topics.archived')
+        end
+      end
+
       guardian = Guardian.new(@user)
       unless guardian.is_staff?
         allowed_ids = guardian.allowed_category_ids