Revert "Migrates alerts to an object-oriented implementation"

This reverts commit fbc283f12f.

scripts/lua/modules/alert_definitions/alert_slow_periodic_activity.lua

@@ -2,63 +2,53 @@
 -- (C) 2019-20 - ntop.org
 --
 
--- ##############################################
-
 local dirs = ntop.getDirs()
 local alert_keys = require "alert_keys"
 
 package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
 local format_utils = require "format_utils"
 
--- Import the classes library.
-local classes = require "classes"
--- Make sure to import the Superclass!
-local alert = require "alert"
-
--- ##############################################
-
-local alert_slow_periodic_activity = classes.class(alert)
-
--- ##############################################
-
-alert_slow_periodic_activity.meta = {
-  alert_key = alert_keys.ntopng.alert_slow_periodic_activity,
-  i18n_title = "alerts_dashboard.slow_periodic_activity",
-  icon = "fas fa-undo",
-}
-
--- ##############################################
+-- #######################################################
 
 -- @brief Prepare an alert table used to generate the alert
+-- @param alert_severity A severity as defined in `alert_severities`
+-- @param alert_granularity A granularity as defined in `alert_consts.alerts_granularities`
 -- @param ps_name A string with the name of the periodic activity
 -- @param max_duration_ms The maximum duration taken by this periodic activity to run, in milliseconds
 -- @return A table with the alert built
-function alert_slow_periodic_activity:init(ps_name, max_duration_ms)
-   -- Call the paren constructor
-   self.super:init()
-
-   self.alert_type_params = {
-      ps_name = ps_name,
-      max_duration_ms = max_duration_ms,
+local function createSlowPeriodicActivity(alert_severity, alert_granularity, ps_name, max_duration_ms)
+   local threshold_type = {
+      alert_severity = alert_severity,
+      alert_granularity = alert_granularity,
+      alert_subtype = ps_name,
+      alert_type_params = {
+	 ps_name = ps_name,
+	 max_duration_ms = max_duration_ms,
+      },
    }
+
+   return threshold_type
 end
 
 -- #######################################################
 
--- @brief Format an alert into a human-readable string
--- @param ifid The integer interface id of the generated alert
--- @param alert The alert description table, including alert data such as the generating entity, timestamp, granularity, type
--- @param alert_type_params Table `alert_type_params` as built in the `:init` method
--- @return A human-readable string
-function alert_slow_periodic_activity.format(ifid, alert, alert_type_params)
+local function slowPeriodicActivityFormatter(ifid, alert, info)
   local max_duration
 
-  max_duration = format_utils.secondsToTime(alert_type_params.max_duration_ms / 1000)
+  max_duration = format_utils.secondsToTime(info.max_duration_ms / 1000)
 
   return(i18n("alert_messages.slow_periodic_activity", {
-    script = alert_type_params.ps_name,
+    script = info.ps_name,
     max_duration = max_duration,
   }))
 end
 
-return alert_slow_periodic_activity
+-- #######################################################
+
+return {
+  alert_key = alert_keys.ntopng.alert_slow_periodic_activity,
+  i18n_title = "alerts_dashboard.slow_periodic_activity",
+  i18n_description = slowPeriodicActivityFormatter,
+  icon = "fas fa-undo",
+  creator = createSlowPeriodicActivity,
+}