(() => {
  const formSelector = "form[data-submit-once]";

  function progressIndicator() {
    return document.getElementById("submit-progress");
  }

  function resetForm(form) {
    form.removeAttribute("aria-busy");
    delete form.dataset.submitting;

    const button = form.querySelector("[data-submit-button]");
    if (!button) {
      return;
    }
    button.disabled = false;
    button.removeAttribute("aria-disabled");
    if (button.dataset.idleLabel) {
      button.textContent = button.dataset.idleLabel;
      delete button.dataset.idleLabel;
    }
  }

  document.addEventListener("submit", (event) => {
    const form = event.target.closest(formSelector);
    if (!form) {
      return;
    }
    if (form.dataset.submitting === "true") {
      event.preventDefault();
      return;
    }

    form.dataset.submitting = "true";
    form.setAttribute("aria-busy", "true");

    const button = event.submitter || form.querySelector("[data-submit-button]");
    if (button) {
      button.dataset.idleLabel = button.textContent;
      button.textContent = form.dataset.submittingLabel || "Posting…";
      button.disabled = true;
      button.setAttribute("aria-disabled", "true");
    }

    const progress = progressIndicator();
    if (progress) {
      progress.hidden = false;
    }
  });

  window.addEventListener("pageshow", () => {
    document.querySelectorAll(formSelector).forEach(resetForm);
    const progress = progressIndicator();
    if (progress) {
      progress.hidden = true;
    }
  });
})();