(function () {
  const STORAGE_KEY = "otb_theme";
  const root = document.documentElement;

  function getPreferredTheme() {
    const saved = localStorage.getItem(STORAGE_KEY);
    if (saved === "light" || saved === "dark") return saved;
    return "dark";
  }

  function applyTheme(theme) {
    root.setAttribute("data-theme", theme);
    const toggle = document.getElementById("otbThemeToggle");
    if (toggle) {
      toggle.checked = theme === "dark";
    }
  }

  function saveTheme(theme) {
    localStorage.setItem(STORAGE_KEY, theme);
  }

  function initThemeToggle() {
    const toggle = document.getElementById("otbThemeToggle");
    if (!toggle) return;

    toggle.addEventListener("change", function () {
      const theme = toggle.checked ? "dark" : "light";
      applyTheme(theme);
      saveTheme(theme);
    });
  }

  function init() {
    applyTheme(getPreferredTheme());
    initThemeToggle();
  }

  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", init);
  } else {
    init();
  }
})();