'use strict';

(() => {
  const monthImage = document.getElementById('month-image');
  const monthPeriod = document.getElementById('month-period');
  const decadeDay = document.getElementById('decade-day');
  const republicanDate = document.getElementById('republican-date');
  const republicanYear = document.getElementById('republican-year');
  const sextileBadge = document.getElementById('sextile-badge');
  const gregorianEquivalentValue = document.getElementById('gregorian-equivalent-value');
  const monthName = document.getElementById('month-name');
  const monthSeasonSuffix = document.getElementById('month-season-suffix');
  const monthEtymology = document.getElementById('month-etymology');
  const monthDescription = document.getElementById('month-description');

  const dateInput = document.getElementById('date-input');
  const convertForm = document.getElementById('convert-form');
  const todayButton = document.getElementById('today-button');
  const formError = document.getElementById('form-error');

  const viewHome = document.getElementById('view-home');
  const viewCalendar = document.getElementById('view-calendar');
  const viewAbout = document.getElementById('view-about');
  const aboutTitle = document.getElementById('about-title');
  const aboutContent = document.getElementById('about-content');

  const posterGrid = document.getElementById('poster-grid');
  const posterFeasts = document.getElementById('poster-feasts');
  const monthDialog = document.getElementById('month-dialog');
  const dialogImage = document.getElementById('dialog-image');
  const dialogName = document.getElementById('dialog-name');
  const dialogPeriod = document.getElementById('dialog-period');
  const dialogEtymology = document.getElementById('dialog-etymology');
  const dialogDescription = document.getElementById('dialog-description');

  const menuToggle = document.getElementById('menu-toggle');
  const mainNav = document.getElementById('main-nav');
  const navBackdrop = document.getElementById('nav-backdrop');
  const langSwitch = document.getElementById('lang-switch');

  const ABOUT_ROUTES = {
    'about/history': 'history',
    'about/leap-years': 'leapYears',
    'about/complementary-days': 'complementaryDays',
  };

  // Season columns of the full calendar; `image` is the month plate shown in the arch,
  // `focus` its vertical crop position so that the face stays in the arch.
  const SEASONS = [
    { key: 'autumn', image: 'vendemiaire', focus: '23%', months: ['vendemiaire', 'brumaire', 'frimaire'] },
    { key: 'winter', image: 'nivose', focus: '18%', months: ['nivose', 'pluviose', 'ventose'] },
    { key: 'spring', image: 'floreal', focus: '18%', months: ['germinal', 'floreal', 'prairial'] },
    { key: 'summer', image: 'messidor', focus: '18%', months: ['messidor', 'thermidor', 'fructidor'] },
  ];

  const DECADE_DAY_KEYS = [
    'primidi', 'duodi', 'tridi', 'quartidi', 'quintidi',
    'sextidi', 'septidi', 'octidi', 'nonidi', 'decadi',
  ];

  const COMPLEMENTARY_DAY_KEYS = ['virtue', 'genius', 'labour', 'opinion', 'rewards', 'revolution'];

  let lastRepublicanResult = null;
  let dayNames = {};

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

  function toIsoDate({ year, month, day }) {
    return `${String(year).padStart(4, '0')}-${pad(month)}-${pad(day)}`;
  }

  function formatGregorian({ year, month, day }, weekdayKey) {
    const weekdayLabel = I18N.t(`weekdays.${weekdayKey}`, '');
    return `${weekdayLabel} ${pad(day)}/${pad(month)}/${year}`.trim();
  }

  function createElement(tag, className, text) {
    const element = document.createElement(tag);
    if (className) element.className = className;
    if (text !== undefined) element.textContent = text;
    return element;
  }

  function closeMenu() {
    mainNav.classList.remove('open');
    mainNav.setAttribute('aria-hidden', 'true');
    navBackdrop.hidden = true;
    menuToggle.setAttribute('aria-expanded', 'false');
  }

  function openMenu() {
    mainNav.classList.add('open');
    mainNav.setAttribute('aria-hidden', 'false');
    navBackdrop.hidden = false;
    menuToggle.setAttribute('aria-expanded', 'true');
  }

  function renderRepublicanResult(result) {
    lastRepublicanResult = result;
    const months = I18N.months.months || {};
    const decadeDays = I18N.months.decadeDays || {};
    const complementary = I18N.months.complementaryDays || { days: {} };

    sextileBadge.hidden = !result.isSextile;
    gregorianEquivalentValue.textContent = formatGregorian(result.gregorianDate, result.gregorianWeekdayKey);
    republicanYear.textContent = `${I18N.t('home.yearLabel')} ${result.republicanYearRoman} (${result.republicanYear})`;

    if (result.isComplementaryDay) {
      const day = complementary.days[result.complementaryDayKey] || {};
      decadeDay.textContent = complementary.title || '';
      republicanDate.textContent = day.name || '';
      monthImage.src = 'assets/complementary.svg';
      monthImage.alt = day.name || '';
      monthPeriod.textContent = '';
      monthName.textContent = day.name || '';
      monthSeasonSuffix.textContent = '';
      monthEtymology.textContent = '';
      monthDescription.textContent = day.description || '';
    } else {
      const month = months[result.monthKey] || {};
      const seasonSuffix = (I18N.months.seasonSuffix || {})[month.season] || '';
      decadeDay.textContent = decadeDays[result.decadeDayKey] || '';
      republicanDate.textContent = `${result.dayOfMonth} ${month.name || ''}`.trim();
      monthImage.src = `assets/months/${result.monthKey}.jpg`;
      monthImage.alt = month.name || '';
      monthPeriod.textContent = month.period || '';
      monthName.textContent = month.name || '';
      monthSeasonSuffix.textContent = seasonSuffix;
      monthEtymology.textContent = month.etymology || '';
      monthDescription.textContent = month.description || '';
    }
    markToday();
  }

  /** Highlights the displayed republican date inside the full calendar. */
  function markToday() {
    posterGrid.querySelectorAll('.today, .today-row, .is-current').forEach((element) => {
      element.classList.remove('today', 'today-row', 'is-current');
    });
    posterFeasts.querySelectorAll('.today').forEach((element) => element.classList.remove('today'));

    const result = lastRepublicanResult;
    if (!result) return;

    if (result.isComplementaryDay) {
      const feast = posterFeasts.querySelector(`[data-feast="${result.complementaryDayKey}"]`);
      if (feast) feast.classList.add('today');
      return;
    }

    const cell = posterGrid.querySelector(
      `td[data-month="${result.monthKey}"][data-day="${result.dayOfMonth}"]`
    );
    if (cell) {
      cell.classList.add('today');
      cell.parentElement.firstElementChild.classList.add('today-row');
    }
    const monthButton = posterGrid.querySelector(`.month-button[data-month="${result.monthKey}"]`);
    if (monthButton) monthButton.classList.add('is-current');
  }

  function buildSeasonTable(season) {
    const months = I18N.months.months || {};
    const decadeDays = I18N.months.decadeDays || {};
    const decades = I18N.t('calendar.decades', []);

    const table = createElement('table', 'season-table');
    const colgroup = table.appendChild(document.createElement('colgroup'));
    colgroup.appendChild(createElement('col', 'col-day'));
    season.months.forEach(() => colgroup.appendChild(document.createElement('col')));

    const headRow = table.createTHead().insertRow();
    headRow.appendChild(createElement('th', 'day-head', I18N.t('calendar.dayColumn')));
    season.months.forEach((monthKey) => {
      const th = createElement('th');
      th.scope = 'col';
      const button = createElement('button', 'month-button', (months[monthKey] || {}).name || monthKey);
      button.type = 'button';
      button.dataset.month = monthKey;
      th.appendChild(button);
      headRow.appendChild(th);
    });

    const body = table.createTBody();
    for (let decade = 0; decade < 3; decade += 1) {
      const decadeRow = body.insertRow();
      decadeRow.className = 'decade-row';
      const decadeHead = createElement('th', '', decades[decade] || '');
      decadeHead.colSpan = season.months.length + 1;
      decadeRow.appendChild(decadeHead);

      for (let index = 0; index < 10; index += 1) {
        const day = decade * 10 + index + 1;
        const row = body.insertRow();
        if (index === 9) row.className = 'decade-end';

        const dayHead = createElement('th');
        dayHead.scope = 'row';
        dayHead.appendChild(createElement('span', 'day-number', String(day)));
        const decadeDayName = decadeDays[DECADE_DAY_KEYS[index]] || '';
        const abbreviation = createElement('abbr', '', `${decadeDayName.slice(0, 3)}.`);
        abbreviation.title = decadeDayName;
        dayHead.appendChild(abbreviation);
        row.appendChild(dayHead);

        season.months.forEach((monthKey) => {
          const cell = createElement('td', '', (dayNames[monthKey] || [])[day - 1] || '');
          cell.dataset.month = monthKey;
          cell.dataset.day = String(day);
          row.appendChild(cell);
        });
      }
    }
    return table;
  }

  function buildSeason(season) {
    const section = createElement('section', 'season');
    const arch = createElement('div', 'arch');
    const image = createElement('img');
    image.src = `assets/months/${season.image}.jpg`;
    image.alt = '';
    image.loading = 'lazy';
    image.style.objectPosition = `50% ${season.focus}`;
    arch.appendChild(image);
    section.appendChild(arch);
    section.appendChild(createElement('h2', 'season-title', I18N.t(`calendar.seasons.${season.key}`)));
    section.appendChild(buildSeasonTable(season));
    return section;
  }

  function buildPosterCenter() {
    const center = createElement('aside', 'poster-center');
    const medallion = createElement('div', 'medallion');
    const inner = createElement('div', 'medallion-inner');
    const fasces = createElement('img');
    fasces.src = 'assets/fasces.svg';
    fasces.alt = '';
    inner.appendChild(fasces);
    medallion.appendChild(inner);
    center.appendChild(medallion);

    const explanation = createElement('div', 'explanation');
    explanation.appendChild(createElement('h2', '', I18N.t('calendar.explanationTitle')));
    I18N.t('calendar.explanation', []).forEach((paragraph) => {
      explanation.appendChild(createElement('p', '', paragraph));
    });
    center.appendChild(explanation);
    return center;
  }

  function buildFeasts() {
    const complementary = I18N.months.complementaryDays || { days: {} };
    const decadeDays = I18N.months.decadeDays || {};
    posterFeasts.replaceChildren();
    COMPLEMENTARY_DAY_KEYS.forEach((key, index) => {
      const feast = createElement('p', 'feast');
      feast.dataset.feast = key;
      feast.appendChild(createElement('span', 'feast-day', decadeDays[DECADE_DAY_KEYS[index]] || ''));
      feast.appendChild(createElement('span', 'feast-name', (complementary.days[key] || {}).name || ''));
      if (key === 'revolution') {
        feast.appendChild(createElement('span', 'feast-note', I18N.t('calendar.sextileOnly')));
      }
      posterFeasts.appendChild(feast);
    });
  }

  function renderCalendarView() {
    posterGrid.replaceChildren(...SEASONS.map(buildSeason), buildPosterCenter());
    buildFeasts();
    markToday();
  }

  function openMonthDialog(monthKey) {
    const month = (I18N.months.months || {})[monthKey];
    if (!month) return;
    dialogImage.src = `assets/months/${monthKey}.jpg`;
    dialogImage.alt = month.name;
    dialogName.textContent = month.name;
    dialogPeriod.textContent = month.period || '';
    dialogEtymology.textContent = month.etymology || '';
    dialogDescription.textContent = month.description || '';
    monthDialog.showModal();
  }

  async function loadDayNames() {
    try {
      const response = await fetch('data/day-names.json');
      dayNames = await response.json();
    } catch (error) {
      dayNames = {};
    }
  }

  function showFormError(messageKey) {
    formError.textContent = I18N.t(messageKey);
    formError.hidden = false;
  }

  function hideFormError() {
    formError.hidden = true;
    formError.textContent = '';
  }

  async function fetchAndRender(url) {
    hideFormError();
    const response = await fetch(url);
    const payload = await response.json();
    if (!payload.ok) {
      if (payload.error === 'BEFORE_EPOCH') {
        showFormError('form.errorBeforeEpoch');
      } else if (payload.error === 'INVALID_DATE') {
        showFormError('form.errorInvalid');
      } else {
        showFormError('form.errorGeneric');
      }
      return;
    }
    renderRepublicanResult(payload.republicanDate);
    dateInput.value = toIsoDate(payload.republicanDate.gregorianDate);
  }

  async function loadToday() {
    try {
      await fetchAndRender('/api/today');
    } catch (error) {
      showFormError('form.errorGeneric');
    }
  }

  async function handleConvertSubmit(event) {
    event.preventDefault();
    const value = dateInput.value; // yyyy-mm-dd from <input type="date">
    if (!value) return;
    const [year, month, day] = value.split('-').map((part) => Number.parseInt(part, 10));
    try {
      await fetchAndRender(`/api/convert?year=${year}&month=${month}&day=${day}`);
    } catch (error) {
      showFormError('form.errorGeneric');
    }
  }

  function renderAboutView(sectionKey) {
    const section = I18N.about[sectionKey];
    if (!section) return;
    aboutTitle.textContent = section.title;
    aboutContent.innerHTML = '';
    (section.sections || []).forEach((block) => {
      const heading = document.createElement('h2');
      heading.textContent = block.heading;
      aboutContent.appendChild(heading);
      (block.paragraphs || []).forEach((paragraph) => {
        const p = document.createElement('p');
        p.textContent = paragraph;
        aboutContent.appendChild(p);
      });
    });
  }

  function route() {
    const hash = window.location.hash.replace(/^#\/?/, '');
    closeMenu();

    document.querySelectorAll('.nav-link').forEach((link) => link.classList.remove('active'));

    viewHome.hidden = true;
    viewCalendar.hidden = true;
    viewAbout.hidden = true;

    let activeHref = '#/';
    if (hash === 'calendar') {
      viewCalendar.hidden = false;
      activeHref = '#/calendar';
    } else if (hash in ABOUT_ROUTES) {
      viewAbout.hidden = false;
      renderAboutView(ABOUT_ROUTES[hash]);
      activeHref = `#/${hash}`;
    } else {
      viewHome.hidden = false;
    }
    const activeLink = document.querySelector(`.nav-link[href="${activeHref}"]`);
    if (activeLink) activeLink.classList.add('active');
  }

  function bindEvents() {
    menuToggle.addEventListener('click', () => {
      if (mainNav.classList.contains('open')) {
        closeMenu();
      } else {
        openMenu();
      }
    });
    navBackdrop.addEventListener('click', closeMenu);
    window.addEventListener('hashchange', route);

    posterGrid.addEventListener('click', (event) => {
      const button = event.target.closest('.month-button');
      if (button) openMonthDialog(button.dataset.month);
    });
    // A click on the ::backdrop targets the dialog itself, outside its box.
    monthDialog.addEventListener('click', (event) => {
      const box = monthDialog.getBoundingClientRect();
      const inside = event.clientX >= box.left && event.clientX <= box.right
        && event.clientY >= box.top && event.clientY <= box.bottom;
      if (!inside) monthDialog.close();
    });

    convertForm.addEventListener('submit', handleConvertSubmit);
    todayButton.addEventListener('click', () => {
      loadToday();
    });

    langSwitch.addEventListener('click', async () => {
      const nextLang = I18N.currentLang === 'fr' ? 'en' : 'fr';
      await I18N.setLang(nextLang);
    });

    I18N.onChange((lang) => {
      langSwitch.textContent = lang.toUpperCase();
      renderCalendarView();
      if (lastRepublicanResult) {
        renderRepublicanResult(lastRepublicanResult);
      }
      if (!viewAbout.hidden) {
        const hash = window.location.hash.replace(/^#\/?/, '');
        if (hash in ABOUT_ROUTES) renderAboutView(ABOUT_ROUTES[hash]);
      }
    });
  }

  async function init() {
    bindEvents();
    const initialLang = I18N.detectInitialLang();
    await loadDayNames();
    await I18N.load(initialLang);
    langSwitch.textContent = initialLang.toUpperCase();
    route();
    await loadToday();
  }

  init();
})();