From bd87e5acf5361ee37bfcc85a8571e1dbf4323507 Mon Sep 17 00:00:00 2001
From: Klemek <klemek.dev@proton.me>
Date: Wed, 29 Jul 2026 15:14:26 +0200
Subject: [PATCH] refactor: perfect cron rule string

---
 resources/ts/lib/recurrence.ts | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/resources/ts/lib/recurrence.ts b/resources/ts/lib/recurrence.ts
index 59aa2a6..cb7860a 100644
--- a/resources/ts/lib/recurrence.ts
+++ b/resources/ts/lib/recurrence.ts
@@ -7,7 +7,7 @@ const ONE_TIME_VALUE = "@one-time";
 export function parseCron(cron: string | null): {
     type: CronType;
     value: number;
-    date: Date|null;
+    date: Date | null;
 } {
     let value: RegExpMatchArray | null;
     if (cron === null) {
@@ -22,7 +22,7 @@ export function parseCron(cron: string | null): {
             value: 0,
             date: null,
         };
-    } else if (cron.startsWith("RRULE:")) {
+    } else if (cron.startsWith("RRULE:") || cron.startsWith("DTSTART:")) {
         return parseRrule(cron);
     } else if ((value = /^0 (\d+) \* \* \*$/i.exec(cron)) !== null) {
         return {
@@ -145,11 +145,23 @@ export function getCron(
         case CronType.EVERY_YEAR:
             return `0 0 1 ${value.toFixed(0)} *`;
         case CronType.EVERY_N_MONTHS:
-            return `RRULE:FREQ=MONTHLY;INTERVAL=${value.toFixed(0)}\nDTSTART:${dtStartFormat(date)}`;
+            return new RRule({
+                freq: RRule.MONTHLY,
+                interval: value,
+                dtstart: date,
+            }).toString();
         case CronType.EVERY_N_WEEKS:
-            return `RRULE:FREQ=WEEKLY;INTERVAL=${value.toFixed(0)}\nDTSTART:${dtStartFormat(date)}`;
+            return new RRule({
+                freq: RRule.WEEKLY,
+                interval: value,
+                dtstart: date,
+            }).toString();
         case CronType.EVERY_N_DAYS:
-            return `RRULE:FREQ=DAILY;INTERVAL=${value.toFixed(0)}\nDTSTART:${dtStartFormat(date)}`;
+            return new RRule({
+                freq: RRule.DAILY,
+                interval: value,
+                dtstart: date,
+            }).toString();
         case CronType.CUSTOM:
             if (validCron(fallback)) {
                 return fallback;
@@ -160,7 +172,7 @@ export function getCron(
 }
 
 function dtStartFormat(date: Date): string {
-    return `${date.getFullYear().toFixed(0)}${(date.getMonth() + 1).toFixed(0).padStart(2, '0')}${date.getDate().toFixed(0).padStart(2, '0')}T000000Z`
+    return `${date.getFullYear().toFixed(0)}${(date.getMonth() + 1).toFixed(0).padStart(2, "0")}${date.getDate().toFixed(0).padStart(2, "0")}T000000Z`;
 }
 
 export function isOneTime(cron: string | null): boolean {