Werkjaren begrijpen, de seizoenen in Kaspert

/**
 * Werkjaar utility functions.
 * A werkjaar runs from September 1 to August 31.
 * Format: "2025-2026"
 */

/** Get the current werkjaar based on today's date */
export function getCurrentWerkjaar(date: Date = new Date()): string {
  const month = date.getMonth() + 1; // 1-based
  const year = date.getFullYear();
  if (month < 9) {
    return `${year - 1}-${year}`;
  }
  return `${year}-${year + 1}`;
}

/** Get unique werkjaren from a list, sorted descending */
export function getUniqueWerkjaren(werkjaren: string[]): string[] {
  return [...new Set(werkjaren)].sort().reverse();
}