(function () {
  var SESSION_KEY = "ageConfirmed";
  var mask = document.getElementById("eightPop");
  if (!mask) return;

  function getSessionValue(key) {
    try {
      return window.sessionStorage.getItem(key) || "";
    } catch (e) {
      return "";
    }
  }

  function setSessionValue(key, value) {
    try {
      window.sessionStorage.setItem(key, value);
    } catch (e) {
      // sessionStorage 不可用时，本页仍允许正常确认并关闭弹窗。
    }
  }

  function openDialog() {
    mask.hidden = false;
    mask.removeAttribute("hidden");
    mask.classList.add("is-open");
    document.body.style.overflow = "hidden";
  }

  function closeDialog() {
    mask.classList.remove("is-open");
    mask.hidden = true;
    mask.setAttribute("hidden", "");
    document.body.style.overflow = "";
    document.dispatchEvent(new CustomEvent("eightpop:closed"));
  }

  function confirmAge() {
    setSessionValue(SESSION_KEY, "1");
    closeDialog();
  }

  function exitSite() {
    try {
      window.location.replace("about:blank");
    } catch (e) {
      window.location.href = "about:blank";
    }
  }

  // 确认按钮和右下角关闭按钮（X）都视为确认年龄并进入网站。
  var confirmBtns = mask.querySelectorAll("[data-eight-pop-confirm]");
  var exitBtns = mask.querySelectorAll("[data-eight-pop-exit]");
  confirmBtns.forEach(function (button) {
    button.addEventListener("click", confirmAge);
  });
  exitBtns.forEach(function (button) {
    button.addEventListener("click", exitSite);
  });

  if (getSessionValue(SESSION_KEY) !== "1") {
    openDialog();
  }
})();