Update calendar with multi-select

frontend/src/utils/dates.ts

@@ -62,3 +62,42 @@ export function getMonthName(date: Date): string {
   const formatter = new Intl.DateTimeFormat('sv-SE', { month: 'long' })
   return formatter.format(date)
 }
+
+/**
+ * Get ISO week number (1-53) for a date.
+ * ISO-8601: Monday-first, week 1 = contains the year's first Thursday.
+ */
+export function getISOWeekNumber(date: Date): number {
+  if (!isValidDate(date)) return 0
+
+  const d = new Date(date.getTime())
+  d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay() || 7))
+  const yearStart = new Date(Date.UTC(d.getUTCFullYear(), 0, 1))
+  const weekNum = Math.ceil((((d.getTime() - yearStart.getTime()) / 86400000) + 1) / 7)
+
+  return weekNum
+}
+
+/**
+ * Get all dates in a range (inclusive, ascending order, order-independent).
+ * Dates should be ISO strings (YYYY-MM-DD).
+ */
+export function datesInRange(startStr: string, endStr: string): string[] {
+  const start = parseInputDate(startStr)
+  const end = parseInputDate(endStr)
+
+  if (!isValidDate(start) || !isValidDate(end)) {
+    return []
+  }
+
+  const [first, second] = start <= end ? [start, end] : [end, start]
+  const result: string[] = []
+  const current = new Date(first)
+
+  while (current <= second) {
+    result.push(formatDateForInput(current))
+    current.setUTCDate(current.getUTCDate() + 1)
+  }
+
+  return result
+}

frontend/src/utils/leaveTypes.ts

@@ -0,0 +1,17 @@
+export function getColorForType(type: string): string {
+  const colorMap: Record<string, string> = {
+    vacation: '#4CAF50',
+    sjukpenning: '#FF9800',
+    lagsta: '#2196F3',
+  }
+  return colorMap[type] ?? '#9E9E9E'
+}
+
+export function getLabelForType(type: string): string {
+  const labelMap: Record<string, string> = {
+    vacation: 'Vacation',
+    sjukpenning: 'Sick Leave',
+    lagsta: 'Parental',
+  }
+  return labelMap[type] ?? 'Unknown'
+}