add get line msg log api

libs/route-utils/index.js

@@ -134,11 +134,51 @@ const checkSession = async (c, n) => {
   return n()
 }
 
+/**
+ * @typedef pageobj
+ * @prop {number} totalPage
+ * @prop {number} offset
+ * @prop {number} limit
+ * @prop {number} page
+ */
+/**
+ * calculate page object
+ * @param {number} count data row count
+ * @param {number} page page
+ * @param {number} maxItem page show item limit
+ * @return {pageobj}
+ */
+const calPage = function (count, page, maxItem = 10) {
+  if (!count || !isFinite(count) || count < 0) count = 0
+  if (!page || !isFinite(page) || page < 1) page = 1
+  if (!maxItem || !isFinite(maxItem) || maxItem < 1) maxItem = 10
+
+  let totalPage = Math.ceil(count / maxItem)
+  if (totalPage < 1) totalPage = 1
+  if (page > totalPage) page = totalPage
+  let offset = (page - 1) * maxItem
+  if (offset > count) offset = count
+  let limit = maxItem
+
+  totalPage = toInt(totalPage)
+  offset = toInt(offset)
+  limit = toInt(limit)
+  page = toInt(page)
+
+  return {
+    totalPage,
+    offset,
+    limit,
+    page
+  }
+}
+
 module.exports = {
   chkObject,
   resObject,
   toInt,
   APIError,
   genError,
-  checkSession
+  checkSession,
+  calPage
 }