/* Copyright (c) 2025-2026 马建军. All rights reserved.
 * 专有软件 — 未经授权禁止复制、传播、转售。
 * 详见 LICENSE.zh-CN.txt
 */
(function () {
    var toggle = document.getElementById('nav-toggle');
    var nav = document.getElementById('site-nav');
    var backdrop = document.getElementById('nav-backdrop');
    if (!toggle || !nav) return;

    function openNav() {
        nav.classList.add('open');
        if (backdrop) {
            backdrop.hidden = false;
            backdrop.classList.add('show');
        }
        toggle.setAttribute('aria-expanded', 'true');
        document.body.style.overflow = 'hidden';
    }

    function closeNav() {
        nav.classList.remove('open');
        if (backdrop) {
            backdrop.classList.remove('show');
            backdrop.hidden = true;
        }
        toggle.setAttribute('aria-expanded', 'false');
        document.body.style.overflow = '';
    }

    function isMobileNav() {
        return window.matchMedia('(max-width: 767px)').matches;
    }

    toggle.addEventListener('click', function () {
        if (nav.classList.contains('open')) closeNav();
        else openNav();
    });

    if (backdrop) {
        backdrop.addEventListener('click', closeNav);
    }

    function prefetchNav(href) {
        if (!href || href.indexOf(window.location.origin) !== 0) return;
        if (href === window.location.href) return;
        var links = document.head.querySelectorAll('link[rel="prefetch"]');
        for (var i = 0; i < links.length; i++) {
            if (links[i].href === href) return;
        }
        var link = document.createElement('link');
        link.rel = 'prefetch';
        link.href = href;
        document.head.appendChild(link);
    }

    nav.querySelectorAll('a[href]').forEach(function (link) {
        link.addEventListener('click', function () {
            if (isMobileNav()) closeNav();
        });
        link.addEventListener('mouseenter', function () {
            prefetchNav(link.href);
        });
        link.addEventListener('touchstart', function () {
            prefetchNav(link.href);
        }, { passive: true });
    });

    window.addEventListener('resize', function () {
        if (!isMobileNav()) closeNav();
    });

    document.addEventListener('keydown', function (e) {
        if (e.key === 'Escape') closeNav();
    });
})();