(function () {
  const counters = document.querySelectorAll('.counter');

  function animateCounter(el) {
    const target = +el.getAttribute('data-target');
    const duration = 1800;
    const steps = 60;
    const interval = duration / steps;
    let step = 0;

    // easeOutExpo for natural deceleration
    function easeOutExpo(t) {
      return t === 1 ? 1 : 1 - Math.pow(2, -10 * t);
    }

    const timer = setInterval(() => {
      step++;
      const progress = easeOutExpo(step / steps);
      const current = Math.ceil(progress * target);
      el.setAttribute('data-display', current + '+');

      // update text without breaking shimmer gradient
      el.textContent = current + '+';

      if (step >= steps) {
        clearInterval(timer);
        el.textContent = target + '+';
      }
    }, interval);
  }

  function resetAndAnimate() {
    counters.forEach(el => { el.textContent = '0+'; });
    setTimeout(() => counters.forEach(animateCounter), 300);
  }

  // Intersection Observer — animate on scroll into view
  const observer = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
      if (entry.isIntersecting) {
        counters.forEach(animateCounter);
        observer.disconnect();
      }
    });
  }, { threshold: 0.3 });

  const section = document.querySelector('.achieve-section');
  if (section) observer.observe(section);

  // Loop every 8s
  setInterval(resetAndAnimate, 8000);
})();