const reveals = document.querySelectorAll(".reveal");

const observer = new IntersectionObserver(
  (entries) => {
    entries.forEach((entry) => {
      if (entry.isIntersecting) {
        entry.target.classList.add("on");
        observer.unobserve(entry.target);
      }
    });
  },
  { threshold: 0.18 }
);

reveals.forEach((item, idx) => {
  item.style.transitionDelay = `${Math.min(idx * 45, 280)}ms`;
  observer.observe(item);
});

const navLinks = document.querySelectorAll(".main-nav a");

const sectionObserver = new IntersectionObserver(
  (entries) => {
    entries.forEach((entry) => {
      if (entry.isIntersecting) {
        navLinks.forEach((link) => {
          link.classList.toggle("active", link.getAttribute("href") === `#${entry.target.id}`);
        });
      }
    });
  },
  { threshold: 0.55 }
);

["approach", "services", "cases", "contacts"].forEach((id) => {
  const section = document.getElementById(id);
  if (section) {
    sectionObserver.observe(section);
  }
});