(function () {
  'use strict';

  var config = window.tt5Ldt || {};
  var btn = document.getElementById('tt5-ldt-toggle');
  if (!btn) return;

  var storageKey = config.storageKey || 'tt5_ldt_scheme';
  var cookieName = config.cookieName || 'tt5_ldt_scheme';
  var prefersDark = window.matchMedia('(prefers-color-scheme: dark)');

  function getStoredScheme() {
    try {
      var stored = localStorage.getItem(storageKey);
      if (stored === 'light' || stored === 'dark') {
        return stored;
      }
    } catch (e) {}

    var match = document.cookie.match(
      new RegExp('(?:^|; )' + cookieName.replace(/[.*+?^${}()|[\]\\]/g, '\\$&') + '=([^;]*)')
    );
    if (match) {
      var cookieVal = decodeURIComponent(match[1]);
      if (cookieVal === 'light' || cookieVal === 'dark') {
        return cookieVal;
      }
    }

    return null;
  }

  function getScheme() {
    var stored = getStoredScheme();
    if (stored) {
      return stored;
    }
    return document.documentElement.classList.contains('tt5-ldt-dark')
      ? 'dark'
      : 'light';
  }

  function setCookie(scheme) {
    var path = config.cookiePath || '/';
    var domain = config.cookieDomain ? '; domain=' + config.cookieDomain : '';
    var maxAge = 60 * 60 * 24 * 365;
    document.cookie =
      cookieName +
      '=' +
      encodeURIComponent(scheme) +
      ';path=' +
      path +
      domain +
      ';max-age=' +
      maxAge +
      ';SameSite=Lax';
  }

  function applyScheme(scheme, animate) {
    var root = document.documentElement;
    var isDark = scheme === 'dark';

    if (animate) {
      root.classList.add('tt5-ldt-animate');
      window.setTimeout(function () {
        root.classList.remove('tt5-ldt-animate');
      }, 300);
    }

    root.classList.toggle('tt5-ldt-dark', isDark);
    root.setAttribute('data-tt5-scheme', scheme);

    try {
      localStorage.setItem(storageKey, scheme);
    } catch (e) {}

    setCookie(scheme);
    updateButton(isDark);

    if (config.isLoggedIn && config.ajaxUrl && config.nonce) {
      var body = new FormData();
      body.append('action', 'tt5_ldt_save_scheme');
      body.append('nonce', config.nonce);
      body.append('scheme', scheme);
      fetch(config.ajaxUrl, { method: 'POST', body: body, credentials: 'same-origin' });
    }
  }

  function updateButton(isDark) {
    var i18n = config.i18n || {};
    btn.setAttribute('aria-pressed', isDark ? 'true' : 'false');
    btn.setAttribute(
      'aria-label',
      isDark ? i18n.light || 'Switch to light mode' : i18n.dark || 'Switch to dark mode'
    );
    btn.setAttribute(
      'title',
      isDark ? i18n.lightLabel || 'Light mode' : i18n.darkLabel || 'Dark mode'
    );

    var label = btn.querySelector('.tt5-ldt-toggle__label');
    if (label) {
      label.textContent = isDark ? i18n.lightLabel || 'Light' : i18n.darkLabel || 'Dark';
    }
  }

  btn.addEventListener('click', function () {
    var next = getScheme() === 'dark' ? 'light' : 'dark';
    applyScheme(next, true);
  });

  // First visit: no saved preference — follow system setting until user toggles.
  if (!getStoredScheme() && !document.documentElement.getAttribute('data-tt5-scheme')) {
    applyScheme(prefersDark.matches ? 'dark' : 'light', false);
  } else {
    updateButton(document.documentElement.classList.contains('tt5-ldt-dark'));
  }

  prefersDark.addEventListener('change', function (event) {
    if (getStoredScheme()) {
      return;
    }
    applyScheme(event.matches ? 'dark' : 'light', true);
  });
})();