/**
 * The working-day concept carried over from the OG applications (Day Begin /
 * Day End in the Manager Menu): every dated record stamps the store's opened
 * business date, never the machine clock. The wall clock is display metadata.
 */
export type IsoDate = string // YYYY-MM-DD

export interface BusinessDay {
  tenantId: string
  storeId: string
  date: IsoDate
  openedAt: string
  openedBy: string
  closedAt?: string
  closedBy?: string
}

export function isOpen(day: BusinessDay): boolean {
  return day.closedAt === undefined
}

/** Indian financial year label: 2026-04-01 → "2026-27", 2026-03-31 → "2025-26". */
export function fyOf(date: IsoDate, fyStartMonth = 4): string {
  const [y, m] = [Number(date.slice(0, 4)), Number(date.slice(5, 7))]
  const start = m >= fyStartMonth ? y : y - 1
  return `${start}-${String(start + 1).slice(2)}`
}

/** Short FY marker for document series prefixes: "2026-27" → "26". */
export function fyShort(fy: string): string {
  return fy.slice(2, 4)
}