/**
 * Keep database waits and long scans visible without logging every record.
 * update() also checks elapsed time when a synchronous loop delays timers.
 */
export function createProgress({ log = console.log, intervalMs = 5000, now = Date.now } = {}) {
  if (!Number.isSafeInteger(intervalMs) || intervalMs < 1) throw new Error('进度输出间隔必须为正整数毫秒');
  let message = '';
  let startedAt;
  let lastOutput;
  let closed = false;

  function output(force = false) {
    if (closed || !message) return;
    const current = now();
    if (!force && lastOutput !== undefined && current - lastOutput < intervalMs) return;
    lastOutput = current;
    const seconds = Math.max(0, Math.floor((current - startedAt) / 1000));
    log(message + '（已用时 ' + seconds + ' 秒）');
  }

  const timer = setInterval(() => output(), intervalMs);
  timer.unref?.();

  return {
    stage(value) {
      if (closed) return;
      message = String(value ?? '').trim();
      startedAt = now();
      output(true);
    },
    update(value) {
      if (closed) return;
      message = String(value ?? '').trim();
      if (startedAt === undefined) startedAt = now();
      output();
    },
    close() {
      if (closed) return;
      closed = true;
      clearInterval(timer);
    },
  };
}