From 75e533c1fcdafe31d873f48cfa35de8d21ab780e Mon Sep 17 00:00:00 2001
From: Matthias Hochmeister <matthias.hochmeister@apple.com>
Date: Fri, 27 Mar 2026 07:39:25 +0100
Subject: [PATCH] update

---
 frontend/src/pages/Kalender.tsx | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/frontend/src/pages/Kalender.tsx b/frontend/src/pages/Kalender.tsx
index daed0b5..ee6426e 100644
--- a/frontend/src/pages/Kalender.tsx
+++ b/frontend/src/pages/Kalender.tsx
@@ -181,6 +181,20 @@ function formatTime(isoString: string): string {
   return `${String(d.getHours()).padStart(2, '0')}:${String(d.getMinutes()).padStart(2, '0')}`;
 }
 
+/** Extract HH:MM in LOCAL time from a UTC ISO string */
+function isoToLocalTime(iso: string | null | undefined): string {
+  if (!iso) return '';
+  const d = new Date(iso);
+  return `${String(d.getHours()).padStart(2, '0')}:${String(d.getMinutes()).padStart(2, '0')}`;
+}
+
+/** Extract YYYY-MM-DD in LOCAL time from a UTC ISO string */
+function isoToLocalDate(iso: string | null | undefined): string {
+  if (!iso) return '';
+  const d = new Date(iso);
+  return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`;
+}
+
 function formatDateLong(d: Date): string {
   const days = ['Sonntag', 'Montag', 'Dienstag', 'Mittwoch', 'Donnerstag', 'Freitag', 'Samstag'];
   return `${days[d.getDay()]}, ${d.getDate()}. ${MONTH_LABELS[d.getMonth()]} ${d.getFullYear()}`;
@@ -1180,7 +1194,7 @@ function VeranstaltungFormDialog({
     }
     // Also auto-correct wiederholungBis
     if (wiederholungBis) {
-      const vonDateOnly = form.datum_von.slice(0, 10);
+      const vonDateOnly = isoToLocalDate(form.datum_von);
       if (wiederholungBis < vonDateOnly) {
         setWiederholungBis(vonDateOnly);
       }
@@ -1334,9 +1348,9 @@ function VeranstaltungFormDialog({
             <GermanDateField
               label="Von"
               mode="date"
-              value={form.datum_von}
+              value={isoToLocalDate(form.datum_von)}
               onChange={(isoDate) => {
-                const timeStr = form.datum_von?.substring(11, 16) || '00:00';
+                const timeStr = isoToLocalTime(form.datum_von) || '00:00';
                 const d = new Date(`${isoDate}T${timeStr}:00`);
                 if (isNaN(d.getTime())) return;
                 handleChange('datum_von', d.toISOString());
@@ -1347,9 +1361,9 @@ function VeranstaltungFormDialog({
               <TextField
                 label="Uhrzeit"
                 type="time"
-                value={form.datum_von?.substring(11, 16) || ''}
+                value={isoToLocalTime(form.datum_von)}
                 onChange={(e) => {
-                  const dateStr = form.datum_von?.substring(0, 10) || new Date().toISOString().substring(0, 10);
+                  const dateStr = isoToLocalDate(form.datum_von) || isoToLocalDate(new Date().toISOString());
                   const d = new Date(`${dateStr}T${e.target.value}:00`);
                   if (!isNaN(d.getTime())) handleChange('datum_von', d.toISOString());
                 }}
@@ -1363,9 +1377,9 @@ function VeranstaltungFormDialog({
             <GermanDateField
               label="Bis"
               mode="date"
-              value={form.datum_bis}
+              value={isoToLocalDate(form.datum_bis)}
               onChange={(isoDate) => {
-                const timeStr = form.datum_bis?.substring(11, 16) || '23:59';
+                const timeStr = isoToLocalTime(form.datum_bis) || '23:59';
                 const d = new Date(`${isoDate}T${timeStr}:00`);
                 if (isNaN(d.getTime())) return;
                 handleChange('datum_bis', d.toISOString());
@@ -1376,9 +1390,9 @@ function VeranstaltungFormDialog({
               <TextField
                 label="Uhrzeit"
                 type="time"
-                value={form.datum_bis?.substring(11, 16) || ''}
+                value={isoToLocalTime(form.datum_bis)}
                 onChange={(e) => {
-                  const dateStr = form.datum_bis?.substring(0, 10) || new Date().toISOString().substring(0, 10);
+                  const dateStr = isoToLocalDate(form.datum_bis) || isoToLocalDate(new Date().toISOString());
                   const d = new Date(`${dateStr}T${e.target.value}:00`);
                   if (!isNaN(d.getTime())) handleChange('datum_bis', d.toISOString());
                 }}