/**
 * YCat Theme System — LIGHT / DARK / AUTO
 * - 三态：light / dark / auto（跟随系统）
 * - 持久化到 localStorage('ycat-theme')
 * - 同步更新右上角 #themeToggle 按钮图标与文案
 * - 移除旧版「强制浅色」guard，允许暗色生效
 */
(function () {
  const STORAGE_KEY = 'ycat-theme';
  const MODES = ['light', 'dark', 'auto'];

  function sysPref() {
    try {
      return (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) ? 'dark' : 'light';
    } catch (e) { return 'light'; }
  }

  function apply(mode) {
    const eff = (mode === 'auto') ? sysPref() : mode;
    document.documentElement.setAttribute('data-theme', eff);
    try { localStorage.setItem(STORAGE_KEY, mode); } catch (e) {}
    const btn = document.getElementById('themeToggle');
    if (btn) {
      btn.dataset.mode = mode;
      const ic = btn.querySelector('i');
      if (ic) ic.className = 'fa-solid ' + (mode === 'light' ? 'fa-sun' : mode === 'dark' ? 'fa-moon' : 'fa-circle-half-stroke');
      btn.title = '主题：' + (mode === 'light' ? '浅色' : mode === 'dark' ? '深色' : '跟随系统');
    }
  }

  function current() {
    try { return localStorage.getItem(STORAGE_KEY) || 'light'; } catch (e) { return 'light'; }
  }

  window.setTheme = function (m) { if (MODES.indexOf(m) >= 0) apply(m); };
  window.cycleTheme = function () {
    const i = MODES.indexOf(current());
    apply(MODES[(i + 1) % MODES.length]);
  };
  window.getCurrentTheme = current;
  // 兼容旧调用
  window.toggleTheme = window.cycleTheme;

  let saved = current();
  apply(saved);

  // 跟随系统时实时切换
  if (window.matchMedia) {
    try {
      const mq = window.matchMedia('(prefers-color-scheme: dark)');
      const onChange = function () { if (current() === 'auto') apply('auto'); };
      if (mq.addEventListener) mq.addEventListener('change', onChange);
      else if (mq.addListener) mq.addListener(onChange);
    } catch (e) {}
  }

  // 移动端菜单（保留）
  window.toggleMobileMenu = function () {
    const nav = document.querySelector('.header-nav');
    if (nav) nav.classList.toggle('mobile-open');
  };
  document.addEventListener('click', function (e) {
    const nav = document.querySelector('.header-nav');
    if (nav && e.target.closest('.header-nav a')) nav.classList.remove('mobile-open');
  });
  document.addEventListener('click', function (e) {
    const nav = document.querySelector('.header-nav');
    if (nav && nav.classList.contains('mobile-open') &&
      !e.target.closest('.header-nav') && !e.target.closest('.mobile-menu-btn')) {
      nav.classList.remove('mobile-open');
    }
  });
})();