const UNITS: Record<string, number> = { ms: 1, s: 1_000, m: 60_000, h: 3_600_000, d: 86_400_000 };

export function parseDuration(input: string): number {
  const value = input.trim();
  if (!value) throw new Error("Duração vazia.");
  let total = 0;
  let end = 0;
  const pattern = /(\d+(?:\.\d+)?)(ms|s|m|h|d)/gy;
  while (end < value.length) {
    pattern.lastIndex = end;
    const match = pattern.exec(value);
    if (!match) throw new Error(`Duração inválida: ${input}`);
    const amount = Number(match[1]);
    if (!Number.isFinite(amount) || amount <= 0) throw new Error(`Duração deve ser positiva: ${input}`);
    total += amount * UNITS[match[2]];
    if (!Number.isSafeInteger(total) || total > 2_147_483_647) throw new Error(`Duração excede o limite suportado: ${input}`);
    end = pattern.lastIndex;
  }
  if (!Number.isInteger(total)) throw new Error(`Duração deve resultar em milissegundos inteiros: ${input}`);
  return total;
}

export function formatDuration(ms: number): string {
  if (ms <= 0) return "0s";
  const units: Array<[string, number]> = [["d", 86_400_000], ["h", 3_600_000], ["m", 60_000], ["s", 1_000], ["ms", 1]];
  let rest = Math.floor(ms);
  const parts: string[] = [];
  for (const [label, size] of units) {
    const amount = Math.floor(rest / size);
    if (amount) { parts.push(`${amount}${label}`); rest -= amount * size; }
  }
  return parts.join("");
}