// Small formatting helpers for the booth. Money is integer MINOR units (never a
// float — matches the tariff/ledger model); duration is whole minutes.

/** Format integer minor units + ISO-4217 currency as a major-unit string. */
export function formatMoney(amountMinor: number, currency: string): string {
  const major = amountMinor / 100;
  try {
    return new Intl.NumberFormat(undefined, { style: "currency", currency }).format(major);
  } catch {
    // Unknown/garbled currency code — fall back to a plain number + the code.
    return `${major.toFixed(2)} ${currency}`;
  }
}

/** Human duration between two ISO times, e.g. "2h 14m" / "47m" / "0m". */
export function formatDuration(fromIso: string, toIso: string): string {
  const ms = Date.parse(toIso) - Date.parse(fromIso);
  if (!Number.isFinite(ms) || ms < 0) return "—";
  const mins = Math.floor(ms / 60_000);
  const h = Math.floor(mins / 60);
  const m = mins % 60;
  return h > 0 ? `${h}h ${m}m` : `${m}m`;
}

/** Local time-of-day HH:MM:SS from an ISO string. */
export function formatTime(iso: string | null): string {
  if (!iso) return "—";
  const d = new Date(iso);
  return Number.isNaN(d.getTime()) ? "—" : d.toTimeString().slice(0, 8);
}

/** Calendar-day difference (local) between two dates: 0 = same day, 1 = d is one day
 *  before ref, etc. Compares date parts only (ignores time-of-day). */
function dayDiff(d: Date, ref: Date): number {
  const a = new Date(d.getFullYear(), d.getMonth(), d.getDate());
  const b = new Date(ref.getFullYear(), ref.getMonth(), ref.getDate());
  return Math.round((b.getTime() - a.getTime()) / 86_400_000);
}

/** HH:MM (local, 24h) for the relative-day labels. */
function hhmm(d: Date): string {
  const p = (n: number) => String(n).padStart(2, "0");
  return `${p(d.getHours())}:${p(d.getMinutes())}`;
}

/** Minimal shape of i18next's `t` that we rely on: a string lookup, plus the
 *  `returnObjects` overload used to fetch the month-name array. */
export interface TFn {
  (key: string): string;
  (key: string, opts: { returnObjects: true }): unknown;
}

/** Localized month name (index 0 = January) from the i18n catalog. Browser ICU on
 *  the appliance may lack Albanian data, so we DON'T use Intl — the catalog is the
 *  source of truth. Falls back to a numeric month if the array is missing. */
function monthName(d: Date, t: TFn): string {
  const months = t("common.months", { returnObjects: true });
  if (Array.isArray(months) && typeof months[d.getMonth()] === "string") {
    return months[d.getMonth()] as string;
  }
  return String(d.getMonth() + 1);
}

/**
 * Human, day-relative date+time for sessions/logs/history. An event from earlier
 * today reads "Sot 10:48", yesterday "Dje 17:33", and anything older a localized
 * "17 Qershor 10:48" (month name from the active catalog). Keeps time-of-day on
 * every variant — operators care about it within a shift.
 *
 * `t` supplies the today/yesterday words AND the month names (the appliance browser
 * may lack Albanian Intl data, so month names come from the catalog, not Intl).
 */
export function formatRelativeDateTime(iso: string | null, t: TFn): string {
  if (!iso) return "—";
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return "—";
  const diff = dayDiff(d, new Date());
  if (diff === 0) return `${t("common.today")} ${hhmm(d)}`;
  if (diff === 1) return `${t("common.yesterday")} ${hhmm(d)}`;
  // Older (or future): "17 Qershor 10:48", with the year only if it differs.
  const sameYear = d.getFullYear() === new Date().getFullYear();
  const month = monthName(d, t);
  const date = sameYear ? `${d.getDate()} ${month}` : `${d.getDate()} ${month} ${d.getFullYear()}`;
  return `${date} ${hhmm(d)}`;
}