export const TARGET_2050 = Date.parse('2050-01-01T00:00:00-03:00');

export function remainingTime(now, target = TARGET_2050) {
  const total = Math.max(0, Math.ceil((target - now) / 1000));
  return {
    days: Math.floor(total / 86400),
    hours: Math.floor(total / 3600) % 24,
    minutes: Math.floor(total / 60) % 60,
    seconds: total % 60,
    complete: total === 0,
  };
}

if (typeof document !== 'undefined') {
  const clock = document.querySelector('[data-countdown]');
  if (clock) {
    const fields = [...clock.querySelectorAll('[data-unit]')];
    const indicator = document.querySelector('[data-countdown-status]');
    const yearLabel = document.querySelector('[data-current-year]');
    let interval;
    function render() {
      const now = Date.now();
      const remaining = remainingTime(now);
      for (const field of fields) {
        const value = remaining[field.dataset.unit];
        const text = field.dataset.unit === 'days'
          ? value.toLocaleString('pt-BR') : String(value).padStart(2, '0');
        if (field.textContent !== text) field.textContent = text;
      }
      if (yearLabel) yearLabel.textContent = new Intl.DateTimeFormat('pt-BR', {
        year: 'numeric', timeZone: 'America/Sao_Paulo',
      }).format(now) + ' / AGORA';
      indicator.textContent = remaining.complete ? '2050 COMEÇA AGORA' : 'CONTAGEM REGRESSIVA EM TEMPO REAL';
      if (remaining.complete) clearInterval(interval);
      return remaining.complete;
    }
    function resume() {
      clearInterval(interval);
      const complete = render();
      if (!document.hidden && !complete) interval = setInterval(render, 1000);
    }
    document.addEventListener('visibilitychange', resume);
    resume();
  }
}