(() => {
  "use strict";

  const toggle = document.querySelector("[data-nav-toggle]");
  const nav = document.getElementById("site-nav");
  const scrim = document.querySelector("[data-nav-scrim]");

  function setOpen(open) {
    if (!nav || !toggle) return;
    nav.dataset.open = open ? "true" : "false";
    toggle.setAttribute("aria-expanded", open ? "true" : "false");
    if (scrim) scrim.hidden = !open;
    document.body.style.overflow = open ? "hidden" : "";
    if (open) {
      const first = nav.querySelector("a");
      if (first) first.focus({ preventScroll: true });
    } else {
      toggle.focus({ preventScroll: true });
    }
  }

  function isOpen() {
    return !!nav && nav.dataset.open === "true";
  }

  if (toggle && nav) {
    if (nav.dataset.open !== "true") nav.dataset.open = "false";
    toggle.addEventListener("click", () => setOpen(!isOpen()));
    document.addEventListener("keydown", (event) => {
      if (event.key === "Escape" && isOpen()) setOpen(false);
    });
  }
  if (scrim) scrim.addEventListener("click", () => setOpen(false));

  // Active nav item for the current path (progressive enhancement only).
  try {
    const here = new URL(window.location.href).pathname.replace(/\/$/, "") || "/";
    document.querySelectorAll(".site-nav a[href]").forEach((link) => {
      const target = new URL(link.getAttribute("href"), window.location.origin).pathname.replace(/\/$/, "") || "/";
      if (target === here) link.setAttribute("aria-current", "page");
    });
  } catch {
    /* keep server-rendered navigation as is */
  }

  // Footer year (progressive enhancement only).
  const year = document.querySelector("[data-year]");
  if (year) year.textContent = String(new Date().getFullYear());
})();