const form = document.getElementById('rsvp-form');
const statusNode = document.getElementById('form-status');
const attendanceFields = document.getElementById('attendance-fields');
const attendanceInputs = Array.from(document.querySelectorAll('input[name="attendance"]'));
const successModal = document.getElementById('success-modal');
const successOkButton = document.getElementById('success-ok');
const closeModalNodes = Array.from(document.querySelectorAll('[data-close-modal]'));
const googleCalendarLink = document.getElementById('google-calendar-link');
const iCalDownloadButton = document.getElementById('ical-download');
const copyIbanButton = document.getElementById('copy-iban');
const ibanFeedback = document.getElementById('iban-feedback');
const giftHolder = document.getElementById('gift-holder');
const giftIban = document.getElementById('gift-iban');
const giftCausal = document.getElementById('gift-causal');
const giftNote = document.getElementById('gift-note');

// Modifica qui i dati del calendario evento.
const EVENT_CALENDAR = {
  title: 'Il Gianquarantesimo',
  location: 'Lost Paradise Beach Club, Bacoli',
  description: 'Conferma la tua presenza per i 40 anni del Gianca.',
  date: '2026-04-25',
  startTime: '12:00',
  durationHours: 6,
  timezone: 'Europe/Rome'
};

// Modifica qui i dati regalo / quota viaggio.
const GIFT_DETAILS = {
  holder: 'Flygo S.r.l',
  iban: 'IT 34 O 02008 03450 000011029239',
  causal: 'Lista Compleanno Giancarlo Esposito da parte di ...',
  note: 'Nota facoltativa: un pensiero semplice e sempre gradito.'
};

function updateAttendanceFields() {
  const selected = document.querySelector('input[name="attendance"]:checked');
  const attending = selected?.value === 'si';

  attendanceFields.classList.toggle('attendance-fields--hidden', !attending);

  attendanceFields.querySelectorAll('input, select, textarea').forEach((field) => {
    field.disabled = !attending;
    if (!attending && field.tagName === 'TEXTAREA') field.value = '';
    if (!attending && field.tagName === 'SELECT') field.value = '0';
  });
}

function openSuccessModal() {
  if (!successModal) return;
  successModal.classList.add('success-modal--open');
  successModal.setAttribute('aria-hidden', 'false');
  document.body.classList.add('modal-open');
  successOkButton?.focus();
}

function closeSuccessModal() {
  if (!successModal) return;
  successModal.classList.remove('success-modal--open');
  successModal.setAttribute('aria-hidden', 'true');
  document.body.classList.remove('modal-open');
}

function pad(value) {
  return String(value).padStart(2, '0');
}

function createFloatingDateTime(date, time, plusHours = 0) {
  const [year, month, day] = date.split('-').map(Number);
  const [hours, minutes] = time.split(':').map(Number);
  const normalizedDate = new Date(Date.UTC(year, month - 1, day, hours, minutes, 0));
  normalizedDate.setUTCHours(normalizedDate.getUTCHours() + plusHours);

  return `${normalizedDate.getUTCFullYear()}${pad(normalizedDate.getUTCMonth() + 1)}${pad(normalizedDate.getUTCDate())}T${pad(normalizedDate.getUTCHours())}${pad(normalizedDate.getUTCMinutes())}00`;
}

function buildGoogleCalendarUrl(eventData) {
  const start = createFloatingDateTime(eventData.date, eventData.startTime, 0);
  const end = createFloatingDateTime(eventData.date, eventData.startTime, eventData.durationHours);
  const params = new URLSearchParams({
    action: 'TEMPLATE',
    text: eventData.title,
    details: eventData.description,
    location: eventData.location,
    ctz: eventData.timezone,
    dates: `${start}/${end}`
  });
  return `https://calendar.google.com/calendar/render?${params.toString()}`;
}

function escapeIcsText(value) {
  return value
    .replace(/\\/g, '\\\\')
    .replace(/\n/g, '\\n')
    .replace(/,/g, '\\,')
    .replace(/;/g, '\\;');
}

function buildIcsContent(eventData) {
  const start = createFloatingDateTime(eventData.date, eventData.startTime, 0);
  const end = createFloatingDateTime(eventData.date, eventData.startTime, eventData.durationHours);
  const stamp = `${createFloatingDateTime(eventData.date, eventData.startTime, 0)}Z`;
  const uid = `gianca-40-${start}@gianca-event`;

  return [
    'BEGIN:VCALENDAR',
    'VERSION:2.0',
    'PRODID:-//Gianca40//Event Landing//IT',
    'CALSCALE:GREGORIAN',
    'BEGIN:VEVENT',
    `UID:${uid}`,
    `DTSTAMP:${stamp}`,
    `DTSTART;TZID=${eventData.timezone}:${start}`,
    `DTEND;TZID=${eventData.timezone}:${end}`,
    `SUMMARY:${escapeIcsText(eventData.title)}`,
    `LOCATION:${escapeIcsText(eventData.location)}`,
    `DESCRIPTION:${escapeIcsText(eventData.description)}`,
    'END:VEVENT',
    'END:VCALENDAR'
  ].join('\r\n');
}

function triggerIcsDownload() {
  const content = buildIcsContent(EVENT_CALENDAR);
  const blob = new Blob([content], { type: 'text/calendar;charset=utf-8' });
  const downloadUrl = URL.createObjectURL(blob);
  const link = document.createElement('a');
  link.href = downloadUrl;
  link.download = 'i-40-anni-del-gianca.ics';
  document.body.append(link);
  link.click();
  link.remove();
  URL.revokeObjectURL(downloadUrl);
}

function setIbanFeedback(message) {
  if (!ibanFeedback) return;
  ibanFeedback.textContent = message;
}

async function copyIbanToClipboard() {
  if (!copyIbanButton) return;
  const ibanNodeId = copyIbanButton.dataset.copyTarget;
  const ibanText = document.getElementById(ibanNodeId || '')?.textContent?.trim();
  if (!ibanText) return;

  try {
    await navigator.clipboard.writeText(ibanText);
    setIbanFeedback('IBAN copiato negli appunti.');
  } catch (error) {
    const fallbackField = document.createElement('input');
    fallbackField.value = ibanText;
    document.body.append(fallbackField);
    fallbackField.select();
    const copied = document.execCommand('copy');
    fallbackField.remove();
    setIbanFeedback(copied ? 'IBAN copiato negli appunti.' : 'Copia non riuscita. Riprova.');
  }
}

attendanceInputs.forEach((input) => input.addEventListener('change', updateAttendanceFields));
closeModalNodes.forEach((node) => node.addEventListener('click', closeSuccessModal));
successOkButton?.addEventListener('click', closeSuccessModal);
iCalDownloadButton?.addEventListener('click', triggerIcsDownload);
copyIbanButton?.addEventListener('click', async () => {
  await copyIbanToClipboard();
  window.clearTimeout(copyIbanButton.dataset.feedbackTimeoutId);
  const timeoutId = window.setTimeout(() => setIbanFeedback(''), 2500);
  copyIbanButton.dataset.feedbackTimeoutId = String(timeoutId);
});
document.addEventListener('keydown', (event) => {
  if (event.key === 'Escape' && successModal?.classList.contains('success-modal--open')) {
    closeSuccessModal();
  }
});
updateAttendanceFields();
if (googleCalendarLink) {
  googleCalendarLink.href = buildGoogleCalendarUrl(EVENT_CALENDAR);
}
if (giftHolder) giftHolder.textContent = GIFT_DETAILS.holder;
if (giftIban) giftIban.textContent = GIFT_DETAILS.iban;
if (giftCausal) giftCausal.textContent = GIFT_DETAILS.causal;
if (giftNote) giftNote.textContent = GIFT_DETAILS.note;

function encode(data) {
  return new URLSearchParams(data).toString();
}

form?.addEventListener('submit', async (event) => {
  event.preventDefault();

  if (!form.reportValidity()) return;

  const submitButton = form.querySelector('button[type="submit"]');
  const formData = new FormData(form);

  submitButton.disabled = true;
  statusNode.textContent = 'Invio in corso...';

  try {
    const response = await fetch('/', {
      method: 'POST',
      headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      body: encode(formData)
    });

    if (!response.ok) {
      throw new Error('Submission failed');
    }

    form.reset();
    updateAttendanceFields();
    statusNode.textContent = '';
    openSuccessModal();
  } catch (error) {
    statusNode.textContent = 'C’è stato un problema nell’invio. Riprova tra poco.';
  } finally {
    submitButton.disabled = false;
  }
});