const mode = localStorage.getItem("theme") || "auto";
document.documentElement.dataset.theme = mode;

document.addEventListener("DOMContentLoaded", () => {
  const button = document.querySelector("#theme");
  const label = () =>
    button.setAttribute(
      "aria-label",
      `Theme: ${document.documentElement.dataset.theme}. Change theme`,
    );
  label();

  button.addEventListener("click", () => {
    const modes = ["auto", "light", "dark"];
    const next =
      modes[
        (modes.indexOf(document.documentElement.dataset.theme) + 1) %
          modes.length
      ];
    document.documentElement.dataset.theme = next;
    localStorage.setItem("theme", next);
    label();
  });
});