export type DurationMsParseOptions = {
  defaultUnit?: "ms" | "s" | "m" | "h";
};

export function parseDurationMs(
  raw: string,
  opts?: DurationMsParseOptions,
): number {
  const trimmed = String(raw ?? "")
    .trim()
    .toLowerCase();
  if (!trimmed) throw new Error("invalid duration (empty)");

  const m = /^(\d+(?:\.\d+)?)(ms|s|m|h)?$/.exec(trimmed);
  if (!m) throw new Error(`invalid duration: ${raw}`);

  const value = Number(m[1]);
  if (!Number.isFinite(value) || value < 0) {
    throw new Error(`invalid duration: ${raw}`);
  }

  const unit = (m[2] ?? opts?.defaultUnit ?? "ms") as "ms" | "s" | "m" | "h";
  const multiplier =
    unit === "ms" ? 1 : unit === "s" ? 1000 : unit === "m" ? 60_000 : 3_600_000;
  const ms = Math.round(value * multiplier);
  if (!Number.isFinite(ms)) throw new Error(`invalid duration: ${raw}`);
  return ms;
}