use cron instead of interval

calendar/plugin.json

@@ -4,6 +4,6 @@
   "description": "Plugin for iCalendar/VCS room events",
   "version": "1.1.2",
   "tags": ["commands", "utility", "calendar"],
-  "dependencies": ["simplecommands"],
+  "dependencies": ["simplecommands", "cron"],
   "npmDependencies": ["node-ical@^0.13.0"]
 }

calendar/plugin.ts

@@ -11,8 +11,6 @@ import { logger } from '@squeebot/core/lib/core';
 import { Formatter, IMessage, MessageResolver } from '@squeebot/core/lib/types';
 import { fullIDMatcher, readableTime } from '@squeebot/core/lib/common';
 
-let calendarTimeout: NodeJS.Timeout;
-
 interface CalendarConfiguration {
   name: string;
   url: string;
@@ -126,9 +124,7 @@ function tellEvent(eventData: Event, msg: IMessage, countdown = true): void {
   msg.resolve(keys);
 }
 
-async function fetchCalendars(interval: number): Promise<void> {
-  clearTimeout(calendarTimeout);
-
+async function fetchCalendars(): Promise<void> {
   memcache = [];
   for (const cfg of loaded) {
     let result;
@@ -194,24 +190,17 @@ async function fetchCalendars(interval: number): Promise<void> {
 
     logger.log('[calendar] Fetched %d events from %s.', events, cfg.name);
   }
-
-  calendarTimeout = setTimeout(() => {
-    fetchCalendars(interval).catch(
-      (e) => logger.error('[calendar] fetch error:', e.stack));
-  }, interval * 1000);
 }
 
 @Configurable({
   calendars: [],
-  updateInterval: 1800,
+  updateInterval: '30 * * * *',
 })
 class CalendarPlugin extends Plugin {
   @EventListener('pluginUnload')
   public unloadEventHandler(plugin: string | Plugin): void {
     if (plugin === this.name || plugin === this) {
-      clearTimeout(calendarTimeout);
-      this.config.save().then(() =>
-        this.emit('pluginUnloaded', this));
+      this.emit('pluginUnloaded', this);
     }
   }
 
@@ -223,7 +212,7 @@ class CalendarPlugin extends Plugin {
         plugin: this.name,
         execute: async (msg: IMessage, msr: MessageResolver, spec: any, prefix: string, ...simplified: any[]): Promise<boolean> => {
           if (simplified[0] && simplified[0] === 'refresh') {
-            await fetchCalendars(this.config.get('updateInterval', 1800));
+            await fetchCalendars();
           }
 
           let events = eventsFor(msg);
@@ -310,9 +299,21 @@ class CalendarPlugin extends Plugin {
     }
   }
 
+  @DependencyLoad('cron')
+  public initializeCron(cronPlugin: any): void {
+    const expression = this.config.get('updateInterval', '30 * * * *');
+    cronPlugin.registerTimer(
+      this,
+      expression,
+      () => fetchCalendars().catch(
+        (error) => logger.error('[calendar] fetch error:', error.stack),
+      )
+    );
+  }
+
   initialize(): void {
     this.loadConfig();
-    fetchCalendars(this.config.get('updateInterval', 1800)).catch(
+    fetchCalendars().catch(
       (e) => logger.error('[%s] fetch error:', this.name, e.stack));
   }
 }