(function () {
  var btn = document.getElementById("theme-toggle");
  var choices = Array.prototype.slice.call(document.querySelectorAll("[data-theme-choice]"));
  var media = window.matchMedia("(prefers-color-scheme: dark)");

  if (!btn && choices.length === 0) return;

  function storedTheme() {
    try {
      var value = localStorage.getItem("theme");
      return value === "dark" || value === "light" ? value : "system";
    } catch (_error) {
      return "system";
    }
  }

  var selectedTheme = storedTheme();

  function isDark() {
    var t = document.documentElement.getAttribute("data-theme");
    if (t) return t === "dark";
    return media.matches;
  }

  function icon(dark) {
    if (dark) {
      return '<svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><circle cx="12" cy="12" r="3.5"></circle><path d="M12 2.25v2.25M12 19.5v2.25M2.25 12H4.5M19.5 12h2.25M5.11 5.11 6.7 6.7M17.3 17.3l1.59 1.59M18.89 5.11 17.3 6.7M6.7 17.3l-1.59 1.59"></path></svg>';
    }
    return '<svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M20.25 15.17A8.5 8.5 0 0 1 8.83 3.75 8.5 8.5 0 1 0 20.25 15.17Z"></path></svg>';
  }

  function setTheme(theme) {
    if (theme !== "system" && theme !== "light" && theme !== "dark") return;
    selectedTheme = theme;

    if (theme === "system") {
      document.documentElement.removeAttribute("data-theme");
      try {
        localStorage.removeItem("theme");
      } catch (_error) {
        // The system preference still works when storage is unavailable.
      }
    } else {
      document.documentElement.setAttribute("data-theme", theme);
      try {
        localStorage.setItem("theme", theme);
      } catch (_error) {
        // The current document can still use the requested theme.
      }
    }
    update();
  }

  function update() {
    var dark = isDark();

    if (btn) {
      btn.innerHTML = icon(dark);
      btn.setAttribute("aria-label", dark ? "Use light theme" : "Use dark theme");
      btn.setAttribute("title", dark ? "Use light theme" : "Use dark theme");
    }

    choices.forEach(function (choice) {
      choice.setAttribute("aria-pressed", choice.getAttribute("data-theme-choice") === selectedTheme ? "true" : "false");
    });
  }

  if (btn) {
    btn.addEventListener("click", function () {
      setTheme(isDark() ? "light" : "dark");
    });
  }

  choices.forEach(function (choice) {
    choice.addEventListener("click", function () {
      setTheme(choice.getAttribute("data-theme-choice"));
    });
  });

  if (typeof media.addEventListener === "function") {
    media.addEventListener("change", function () {
      if (selectedTheme === "system") update();
    });
  }

  update();
})();