const webinarUtils = {
  getTimestamp: (dateString) => new Date(dateString).getTime(),

  addDaysToTimestamp: (dateString, days) => {
    const date = new Date(dateString);
    date.setDate(date.getDate() + days);
    return date.getTime();
  },

  setValueAndTrigger: (element, value) => {
    if (!element) return;
    element.value = value.toString();
    element.dispatchEvent(new Event("change", { bubbles: true }));
  },

  extractPrefix: (name) => name.replace(/_webinar_date_list$/, ""),

  updateRemindDate: (doc, prefix, baseDate, index) => {
    const spanEl = doc.querySelector(
      `[name="${prefix}_webinar_remind_span_${index}"]`
    );
    const remindEl = doc.querySelector(
      `[name="${prefix}_webinar_remind_${index}"]`
    );
    if (!spanEl || !remindEl || !baseDate) return;

    const days = parseInt(spanEl.value, 10) || 0; // Treat NaN as 0
    const timestamp = webinarUtils.addDaysToTimestamp(baseDate, -days);
    webinarUtils.setValueAndTrigger(remindEl, timestamp);
  },
};

const initializeWebinarForm = (doc) => {
  const dateListElements = doc.querySelectorAll('[name$="_webinar_date_list"]');
  if (dateListElements.length === 0) return false;

  const prefixes = [
    ...new Set(
      Array.from(dateListElements).map((el) => webinarUtils.extractPrefix(el.name))
    ),
  ];

  prefixes.forEach((prefix) => {
    const dateEl = doc.querySelector(`[name="${prefix}_webinar_date"]`);
    const radioButtons = doc.querySelectorAll(
      `[name="${prefix}_webinar_date_list"]`
    );

    const now = new Date();
    const oneMonthLater = new Date();
    oneMonthLater.setMonth(oneMonthLater.getMonth() + 1);

    radioButtons.forEach((radio) => {
      const radioDate = new Date(radio.value);
      if (radioDate < now || radioDate > oneMonthLater) {
        const parentLabel = radio.closest("label") || radio.parentElement;
        if (parentLabel) {
          parentLabel.style.display = "none";
        }
      }

      radio.addEventListener("change", () => {
        if (!radio.checked) return;

        const selectedValue = radio.value;
        const timestamp = webinarUtils.getTimestamp(selectedValue);

        // Set webinar date
        webinarUtils.setValueAndTrigger(dateEl, timestamp);

        // Set remind dates
        [1, 2].forEach((i) => webinarUtils.updateRemindDate(doc, prefix, selectedValue, i));
      });
    });
  });

  return true;
};