// Shared site chrome behavior: sticky header, accessible mobile menu, hero parallax.
(function () {
  "use strict";

  // ── Sticky header ──────────────────────────────────────────────
  const header = document.getElementById("site-header");
  if (header) {
    const onScroll = () => header.classList.toggle("scrolled", window.scrollY > 40);
    window.addEventListener("scroll", onScroll, { passive: true });
    onScroll();
  }

  // ── Accessible mobile menu (dialog semantics) ──────────────────
  const hamburger = document.getElementById("hamburger");
  const mobileMenu = document.getElementById("mobile-menu");
  const menuClose = document.getElementById("menu-close");

  if (hamburger && mobileMenu && menuClose) {
    const focusable = () =>
      mobileMenu.querySelectorAll('a[href], button:not([disabled])');

    const openMenu = () => {
      mobileMenu.classList.add("open");
      hamburger.setAttribute("aria-expanded", "true");
      menuClose.focus();
      document.addEventListener("keydown", onKeydown);
    };

    const closeMenu = () => {
      mobileMenu.classList.remove("open");
      hamburger.setAttribute("aria-expanded", "false");
      document.removeEventListener("keydown", onKeydown);
      hamburger.focus();
    };

    const onKeydown = (e) => {
      if (e.key === "Escape") {
        closeMenu();
        return;
      }
      if (e.key !== "Tab") return;
      // Focus trap
      const items = focusable();
      if (!items.length) return;
      const first = items[0];
      const last = items[items.length - 1];
      if (e.shiftKey && document.activeElement === first) {
        e.preventDefault();
        last.focus();
      } else if (!e.shiftKey && document.activeElement === last) {
        e.preventDefault();
        first.focus();
      }
    };

    hamburger.addEventListener("click", openMenu);
    menuClose.addEventListener("click", closeMenu);
    mobileMenu.querySelectorAll("a").forEach((a) =>
      a.addEventListener("click", closeMenu)
    );
  }

  // ── Hero parallax (homepage only), rAF-throttled ───────────────
  const heroBg = document.getElementById("hero-bg");
  if (heroBg) {
    let ticking = false;
    const update = () => {
      if (window.scrollY < window.innerHeight) {
        heroBg.style.transform = `scale(1.03) translateY(${window.scrollY * 0.18}px)`;
      }
      ticking = false;
    };
    window.addEventListener(
      "scroll",
      () => {
        if (!ticking) {
          window.requestAnimationFrame(update);
          ticking = true;
        }
      },
      { passive: true }
    );
  }
})();