TopicQuery cleanup in advance of custom sorting:

- Move SQL method constants into a module
- Removed unused count methods
- Moved methods that don't return a TopicList into Topic
- Replaced some confusing method signatures

lib/topic_query_sql.rb

@@ -0,0 +1,72 @@
+#
+#  SQL fragments used when querying a list of topics.
+#
+module TopicQuerySQL
+
+  class << self
+
+    # use the constants in conjuction with COALESCE to determine the order with regard to pinned
+    # topics that have been cleared by the user. There
+    # might be a cleaner way to do this.
+    def lowest_date
+      "2010-01-01"
+    end
+
+    def highest_date
+      "3000-01-01"
+    end
+
+    # If you've clearned the pin, use bumped_at, otherwise put it at the top
+    def order_with_pinned_sql
+      "CASE
+        WHEN (COALESCE(topics.pinned_at, '#{lowest_date}') > COALESCE(tu.cleared_pinned_at, '#{lowest_date}'))
+          THEN '#{highest_date}'
+        ELSE topics.bumped_at
+       END DESC"
+    end
+
+    def order_hotness(user)
+      if user
+        # When logged in take into accounts what pins you've closed
+        "CASE
+          WHEN (COALESCE(topics.pinned_at, '#{lowest_date}') > COALESCE(tu.cleared_pinned_at, '#{lowest_date}'))
+            THEN 100
+          ELSE hot_topics.score + (COALESCE(categories.hotness, 5.0) / 11.0)
+         END DESC"
+      else
+        # When anonymous, don't use topic_user
+        "CASE
+          WHEN topics.pinned_at IS NOT NULL THEN 100
+          ELSE hot_topics.score + (COALESCE(categories.hotness, 5.0) / 11.0)
+        END DESC"
+      end
+    end
+
+    # If you've clearned the pin, use bumped_at, otherwise put it at the top
+    def order_nocategory_with_pinned_sql
+      "CASE
+        WHEN topics.category_id = #{SiteSetting.uncategorized_category_id.to_i} and (COALESCE(topics.pinned_at, '#{lowest_date}') > COALESCE(tu.cleared_pinned_at, '#{lowest_date}'))
+          THEN '#{highest_date}'
+        ELSE topics.bumped_at
+       END DESC"
+    end
+
+    # For anonymous users
+    def order_nocategory_basic_bumped
+      "CASE WHEN topics.category_id = #{SiteSetting.uncategorized_category_id.to_i} and (topics.pinned_at IS NOT NULL) THEN 0 ELSE 1 END, topics.bumped_at DESC"
+    end
+
+    def order_basic_bumped
+      "CASE WHEN (topics.pinned_at IS NOT NULL) THEN 0 ELSE 1 END, topics.bumped_at DESC"
+    end
+
+    def order_with_pinned_sql
+      "CASE
+        WHEN (COALESCE(topics.pinned_at, '#{lowest_date}') > COALESCE(tu.cleared_pinned_at, '#{lowest_date}'))
+          THEN '#{highest_date}'
+        ELSE topics.bumped_at
+       END DESC"
+    end
+
+  end
+end