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helpers/utils.js

@@ -74,6 +74,49 @@ function formatDateTime(dateStr) {
   return date.toLocaleString('de-DE');
 }
 
+// Helper: Berechnet Kalenderwoche aus einem Datum (ISO 8601)
+function getCalendarWeek(dateStr) {
+  const date = new Date(dateStr);
+  const d = new Date(Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()));
+  const dayNum = d.getUTCDay() || 7;
+  d.setUTCDate(d.getUTCDate() + 4 - dayNum);
+  const yearStart = new Date(Date.UTC(d.getUTCFullYear(), 0, 1));
+  const weekNo = Math.ceil((((d - yearStart) / 86400000) + 1) / 7);
+  return weekNo;
+}
+
+// Helper: Berechnet week_start (Montag) und week_end (Sonntag) aus Jahr und Kalenderwoche (ISO 8601)
+function getWeekDatesFromCalendarWeek(year, weekNumber) {
+  // ISO 8601: Woche beginnt am Montag, erste Woche enthält den 4. Januar
+  const jan4 = new Date(Date.UTC(year, 0, 4));
+  const jan4Day = jan4.getUTCDay() || 7; // 1 = Montag, 7 = Sonntag
+  const daysToMonday = jan4Day === 1 ? 0 : 1 - jan4Day;
+  
+  // Montag der ersten Woche
+  const firstMonday = new Date(Date.UTC(year, 0, 4 + daysToMonday));
+  
+  // Montag der gewünschten Woche (Woche 1 = erste Woche)
+  const weekMonday = new Date(firstMonday);
+  weekMonday.setUTCDate(firstMonday.getUTCDate() + (weekNumber - 1) * 7);
+  
+  // Sonntag der Woche (6 Tage nach Montag)
+  const weekSunday = new Date(weekMonday);
+  weekSunday.setUTCDate(weekMonday.getUTCDate() + 6);
+  
+  // Format: YYYY-MM-DD
+  const formatDate = (date) => {
+    const y = date.getUTCFullYear();
+    const m = String(date.getUTCMonth() + 1).padStart(2, '0');
+    const d = String(date.getUTCDate()).padStart(2, '0');
+    return `${y}-${m}-${d}`;
+  };
+  
+  return {
+    week_start: formatDate(weekMonday),
+    week_end: formatDate(weekSunday)
+  };
+}
+
 module.exports = {
   hasRole,
   getDefaultRole,
@@ -82,5 +125,7 @@ module.exports = {
   calculateBreakMinutes,
   updateTotalHours,
   formatDate,
-  formatDateTime
+  formatDateTime,
+  getCalendarWeek,
+  getWeekDatesFromCalendarWeek
 };