add api endpoint to preview babycode

util.lua

@@ -316,4 +316,25 @@ function util.inject_warn_infobox(req, message)
   req.session.infobox = ib
 end
 
+function util.rate_limit_allowed(user_id, method, seconds)
+  local last_call = db.query([[
+    SELECT logged_at FROM api_rate_limits
+    WHERE user_id = ? AND method = ?
+    ORDER BY logged_at DESC LIMIT 1
+  ]], user_id, method)
+  if #last_call == 0 or (os.time() - last_call[1].logged_at) >= seconds then
+    db.query(
+      "DELETE FROM api_rate_limits WHERE user_id = ? AND method = ?",
+      user_id, method
+    )
+    db.query(
+      "INSERT INTO api_rate_limits (user_id, method) VALUES (?, ?)",
+      user_id, method
+    )
+    return true
+  else
+    return false
+  end
+end
+
 return util