utils.ts

// Minimal date helpers to avoid heavy dependency setup in this format
// In a real project, we would rely strictly on date-fns as requested.
// Here we wrap native implementation to ensure it runs standalone.

export const formatDate = (date: Date): string => {
  const y = date.getFullYear();
  const m = String(date.getMonth() + 1).padStart(2, '0');
  const d = String(date.getDate()).padStart(2, '0');
  return `${y}-${m}-${d}`;
};

export const parseDate = (dateStr: string): Date => {
  if (!dateStr) return new Date();
  const [y, m, d] = dateStr.split('-').map(Number);
  return new Date(y, m - 1, d);
};

export const getTodayString = (): string => {
  return formatDate(new Date());
};

export const addDays = (date: Date, days: number): Date => {
  const result = new Date(date);
  result.setDate(result.getDate() + days);
  return result;
};

export const diffInDays = (d1: Date, d2: Date): number => {
  const oneDay = 24 * 60 * 60 * 1000;
  return Math.round((d1.getTime() - d2.getTime()) / oneDay);
};

export const generateId = (): string => {
  return Math.random().toString(36).substring(2, 9);
};