Initial

src/utils/time.js

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+// Hilfsfunktionen für Zeit-/Datumsberechnungen rund um das Arbeitszeitkonto.
+
+const WEEKDAY_NAMES = ['So', 'Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa'];
+
+/** "08:30" -> 510 (Minuten seit Mitternacht) */
+function timeToMinutes(value) {
+  const [h, m] = String(value).split(':').map(Number);
+  return h * 60 + m;
+}
+
+/** 95 -> "1:35" (immer positiv, ohne Vorzeichen) */
+function minutesToHM(totalMinutes) {
+  const abs = Math.abs(Math.round(totalMinutes));
+  const h = Math.floor(abs / 60);
+  const m = abs % 60;
+  return `${h}:${String(m).padStart(2, '0')}`;
+}
+
+/** 95 -> "+1:35", -30 -> "-0:30" */
+function formatBalance(minutes) {
+  const sign = minutes < 0 ? '−' : '+';
+  return `${sign}${minutesToHM(minutes)}`;
+}
+
+/** Prüft, ob ein Datum (YYYY-MM-DD) laut Einstellungen ein Arbeitstag ist. */
+function isWorkDay(dateStr, workDays) {
+  const day = new Date(`${dateStr}T00:00:00`).getDay();
+  return Array.isArray(workDays) && workDays.includes(day);
+}
+
+/** Berechnet die tatsächlich geleisteten Minuten abzüglich Pause. */
+function computeWorkedMinutes(startTime, endTime, breakMinutes) {
+  return timeToMinutes(endTime) - timeToMinutes(startTime) - Number(breakMinutes || 0);
+}
+
+/** Saldo (Über-/Minusstunden) eines einzelnen Tages in Minuten. */
+function computeBalanceMinutes(workedMinutes, dateStr, settings) {
+  const targetMinutes = isWorkDay(dateStr, settings.workDays)
+    ? settings.targetHoursPerDay * 60
+    : 0;
+  return workedMinutes - targetMinutes;
+}
+
+/** "2026-06-23" -> "Di, 23.06.2026" */
+function formatDateDisplay(dateStr) {
+  const date = new Date(`${dateStr}T00:00:00`);
+  return new Intl.DateTimeFormat('de-DE', {
+    weekday: 'short',
+    day: '2-digit',
+    month: '2-digit',
+    year: 'numeric',
+  }).format(date);
+}
+
+/** "2026-06" -> "Juni 2026" */
+function formatMonthDisplay(yearMonth) {
+  const date = new Date(`${yearMonth}-01T00:00:00`);
+  return new Intl.DateTimeFormat('de-DE', { month: 'long', year: 'numeric' }).format(date);
+}
+
+module.exports = {
+  WEEKDAY_NAMES,
+  timeToMinutes,
+  minutesToHM,
+  formatBalance,
+  isWorkDay,
+  computeWorkedMinutes,
+  computeBalanceMinutes,
+  formatDateDisplay,
+  formatMonthDisplay,
+};