ward

const UNIT_MS: Record<string, number> = {
  y: 365 * 24 * 60 * 60 * 1000,
  w: 7 * 24 * 60 * 60 * 1000,
  d: 24 * 60 * 60 * 1000,
  h: 60 * 60 * 1000,
  m: 60 * 1000,
  s: 1000,
};

export function parseDuration(input: string | undefined): number | null {
  if (input == null) return null;
  const s = String(input).trim().toLowerCase();
  if (s === "" || s === "perm" || s === "permanent" || s === "never") {
    return null;
  }

  const matches = s.matchAll(/(\d+)\s*([ywdhms])/g);
  let total = 0;
  let any = false;
  let consumed = 0;
  for (const m of matches) {
    any = true;
    total += Number(m[1]) * UNIT_MS[m[2]];
    consumed += m[0].length;
  }

  const stripped = s.replace(/\s+/g, "");
  if (!any || consumed !== stripped.length) return Number.NaN;
  return total;
}

export function formatDuration(ms: number): string {
  if (!Number.isFinite(ms) || ms <= 0) return "0s";
  const units: [string, number][] = [
    ["y", UNIT_MS.y],
    ["w", UNIT_MS.w],
    ["d", UNIT_MS.d],
    ["h", UNIT_MS.h],
    ["m", UNIT_MS.m],
    ["s", UNIT_MS.s],
  ];
  let remaining = ms;
  const parts: string[] = [];
  for (const [tag, unit] of units) {
    const n = Math.floor(remaining / unit);
    if (n > 0) {
      parts.push(`${n}${tag}`);
      remaining -= n * unit;
    }
    if (parts.length >= 2) break; // 2 components is plenty for display
  }
  return parts.length > 0 ? parts.join("") : "<1s";
}

/** Render an absolute unix-ms expiry as "in 7d" or "expired 3h ago". */
export function describeExpiry(expiryMs: number, now = Date.now()): string {
  const delta = expiryMs - now;
  if (delta <= 0) return `expired ${formatDuration(-delta)} ago`;
  return `in ${formatDuration(delta)}`;
}