add markup to topics list view

apps/topics.lua

@@ -22,7 +22,25 @@ local ThreadCreateError = {
 }
 
 app:get("all_topics", "", function(self)
-  self.topic_list = db.query("select * from topics limit 25;")
+  self.topic_list = db.query([[
+    SELECT
+      topics.name, topics.slug, topics.description, topics.is_locked,
+      users.username AS latest_thread_username,
+      threads.title AS latest_thread_title,
+      threads.slug AS latest_thread_slug,
+      threads.created_at AS latest_thread_created_at
+    FROM
+      topics
+    LEFT JOIN (
+        SELECT
+        *,
+        row_number() OVER (PARTITION BY threads.topic_id ORDER BY threads.created_at DESC) as rn
+      FROM
+        threads
+      ) threads ON threads.topic_id = topics.id AND threads.rn = 1
+    LEFT JOIN
+      users on users.id = threads.user_id
+  ]])
   self.me = util.get_logged_in_user_or_transient(self)
   return {render = "topics.topics"}
 end)