/* global window, document, fetch, URLSearchParams */

(function () {
  'use strict';

  var Luxtools = window.Luxtools || (window.Luxtools = {});

  function findCalendarRoot(target) {
    var el = target;
    while (el && el !== document) {
      if (el.classList && el.classList.contains('luxtools-calendar') && el.getAttribute('data-luxtools-calendar') === '1') {
        return el;
      }
      el = el.parentNode;
    }
    return null;
  }

  function getNextMonth(year, month, direction) {
    var cursor = new Date(year, month - 1, 1);
    cursor.setMonth(cursor.getMonth() + direction);
    return {
      year: cursor.getFullYear(),
      month: cursor.getMonth() + 1
    };
  }

  function parseCalendarFromHtml(html) {
    if (!html) return null;

    var wrapper = document.createElement('div');
    wrapper.innerHTML = html;

    return wrapper.querySelector('div.luxtools-calendar[data-luxtools-calendar="1"]');
  }

  function setCalendarBusy(calendar, busy) {
    if (!calendar) return;

    if (busy) {
      calendar.setAttribute('data-luxtools-loading', '1');
    } else {
      calendar.removeAttribute('data-luxtools-loading');
    }

    var buttons = calendar.querySelectorAll('button.luxtools-calendar-nav-button, button.luxtools-calendar-today-button');
    for (var i = 0; i < buttons.length; i++) {
      buttons[i].disabled = !!busy;
    }
  }

  function getCalendarStateKey(calendar) {
    var baseNs = calendar.getAttribute('data-base-ns') || 'chronological';
    return 'luxtools_calendar_month_' + baseNs.replace(/[^a-zA-Z0-9]/g, '_');
  }

  function shouldPersistCalendarMonth(calendar) {
    return (calendar.getAttribute('data-luxtools-size') || 'large') === 'small';
  }

  function getCookieValue(name) {
    var match = document.cookie.match('(^|;)\\s*' + name.replace(/[.*+?^${}()|[\]\\]/g, '\\$&') + '\\s*=\\s*([^;]+)');
    return match ? decodeURIComponent(match[2]) : null;
  }

  function setCookie(name, value) {
    var date = new Date();
    date.setFullYear(date.getFullYear() + 1);
    document.cookie = name + '=' + encodeURIComponent(value) + '; expires=' + date.toUTCString() + '; path=/; SameSite=Lax';
  }

  function deleteCookie(name) {
    document.cookie = name + '=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/; SameSite=Lax';
  }

  function readSavedCalendarMonth(calendar) {
    if (!shouldPersistCalendarMonth(calendar)) return null;

    try {
      var raw = getCookieValue(getCalendarStateKey(calendar));
      if (!raw) return null;

      var parsed = JSON.parse(raw);
      var year = parseInt(parsed && parsed.year, 10);
      var month = parseInt(parsed && parsed.month, 10);
      if (!year || month < 1 || month > 12) return null;

      return { year: year, month: month };
    } catch (e) {
      return null;
    }
  }

  function saveCalendarMonth(calendar) {
    if (!shouldPersistCalendarMonth(calendar)) return;

    var year = parseInt(calendar.getAttribute('data-current-year') || '', 10);
    var month = parseInt(calendar.getAttribute('data-current-month') || '', 10);
    if (!year || month < 1 || month > 12) return;

    setCookie(getCalendarStateKey(calendar), JSON.stringify({ year: year, month: month }));
  }

  function clearSavedCalendarMonth(calendar) {
    if (!shouldPersistCalendarMonth(calendar)) return;
    deleteCookie(getCalendarStateKey(calendar));
  }

  function fetchCalendarMonth(calendar, year, month) {
    var ajaxUrl = calendar.getAttribute('data-luxtools-ajax-url') || '';
    if (!ajaxUrl) return Promise.reject(new Error('Missing calendar ajax url'));

    var baseNs = calendar.getAttribute('data-base-ns') || 'chronological';
    var size = calendar.getAttribute('data-luxtools-size') || 'large';
    var showTimes = calendar.getAttribute('data-luxtools-show-times') || '1';
    var params = new URLSearchParams({
      call: 'luxtools_calendar_month',
      year: String(year),
      month: String(month),
      base: baseNs,
      size: size,
      show_times: showTimes
    });

    var url = ajaxUrl + (ajaxUrl.indexOf('?') >= 0 ? '&' : '?') + params.toString();

    return fetch(url, {
      method: 'GET',
      credentials: 'same-origin',
      headers: {
        'X-Requested-With': 'XMLHttpRequest'
      }
    }).then(function (response) {
      if (!response.ok) {
        throw new Error('Calendar request failed: ' + response.status);
      }
      return response.text();
    });
  }

  function pad2(num) {
    return num < 10 ? '0' + num : String(num);
  }

  function syncCalendarToday(calendar) {
    if (!calendar) return;

    var todayCells = calendar.querySelectorAll('td.luxtools-calendar-day-today');
    for (var i = 0; i < todayCells.length; i++) {
      todayCells[i].classList.remove('luxtools-calendar-day-today');
    }

    var now = new Date();
    var year = parseInt(calendar.getAttribute('data-current-year') || '', 10);
    var month = parseInt(calendar.getAttribute('data-current-month') || '', 10);
    if (!year || !month) return;

    var currentYear = now.getFullYear();
    var currentMonth = now.getMonth() + 1;
    if (year !== currentYear || month !== currentMonth) return;

    var dateIso = String(currentYear) + '-' + pad2(currentMonth) + '-' + pad2(now.getDate());
    var todayCell = calendar.querySelector('td.luxtools-calendar-day[data-luxtools-date="' + dateIso + '"]');
    if (todayCell) {
      todayCell.classList.add('luxtools-calendar-day-today');
    }
  }

  function replaceCalendar(calendar, replacement, persistState) {
    if (persistState !== false) {
      saveCalendarMonth(replacement);
    }
    syncCalendarToday(replacement);
    calendar.replaceWith(replacement);
    if (Luxtools.initChronologicalEventTimes) {
      Luxtools.initChronologicalEventTimes();
    }
  }

  function loadCalendarMonth(calendar, targetYear, targetMonth, persistState) {
    setCalendarBusy(calendar, true);

    fetchCalendarMonth(calendar, targetYear, targetMonth)
      .then(function (html) {
        var replacement = parseCalendarFromHtml(html);
        if (!replacement) {
          throw new Error('Calendar markup missing in response');
        }

        replaceCalendar(calendar, replacement, persistState);
      })
      .catch(function () {
        window.location.reload();
      })
      .finally(function () {
        setCalendarBusy(calendar, false);
      });
  }

  function navigateCalendarMonth(calendar, direction, persistState) {
    var year = parseInt(calendar.getAttribute('data-current-year') || '', 10);
    var month = parseInt(calendar.getAttribute('data-current-month') || '', 10);
    if (!year || !month) return;

    var next = getNextMonth(year, month, direction);
    loadCalendarMonth(calendar, next.year, next.month, persistState);
  }

  function navigateCalendarToday(calendar) {
    clearSavedCalendarMonth(calendar);

    var now = new Date();
    var year = parseInt(calendar.getAttribute('data-current-year') || '', 10);
    var month = parseInt(calendar.getAttribute('data-current-month') || '', 10);
    if (!year || !month) return;

    var targetYear = now.getFullYear();
    var targetMonth = now.getMonth() + 1;
    var direction = ((targetYear - year) * 12) + (targetMonth - month);
    if (!direction) {
      syncCalendarToday(calendar);
      return;
    }

    navigateCalendarMonth(calendar, direction, false);
  }

  function restoreCalendarMonth(calendar) {
    if (!shouldPersistCalendarMonth(calendar)) return;

    var year = parseInt(calendar.getAttribute('data-current-year') || '', 10);
    var month = parseInt(calendar.getAttribute('data-current-month') || '', 10);
    if (!year || !month) return;

    var saved = readSavedCalendarMonth(calendar);
    if (!saved) {
      var now = new Date();
      var todayYear = now.getFullYear();
      var todayMonth = now.getMonth() + 1;
      if (year !== todayYear || month !== todayMonth) {
        loadCalendarMonth(calendar, todayYear, todayMonth, false);
      }
      return;
    }

    if (saved.year === year && saved.month === month) return;

    loadCalendarMonth(calendar, saved.year, saved.month, true);
  }

  function onCalendarClick(event) {
    var target = event.target;
    if (!target || !target.classList) return;
    if (!target.classList.contains('luxtools-calendar-nav-button') && !target.classList.contains('luxtools-calendar-today-button')) return;

    var calendar = findCalendarRoot(target);
    if (!calendar) return;

    event.preventDefault();

    if (target.getAttribute('data-luxtools-today') === '1') {
      navigateCalendarToday(calendar);
      return;
    }

    var direction = parseInt(target.getAttribute('data-luxtools-dir') || '0', 10);
    if (!direction) return;

    navigateCalendarMonth(calendar, direction, true);
  }

  function updateClientDateCookie() {
    var now = new Date();
    setCookie('luxtools_client_month', JSON.stringify({
      year: now.getFullYear(),
      month: now.getMonth() + 1
    }));
  }

  function initCalendarWidgets() {
    updateClientDateCookie();

    var calendars = document.querySelectorAll('div.luxtools-calendar[data-luxtools-calendar="1"]');
    for (var i = 0; i < calendars.length; i++) {
      syncCalendarToday(calendars[i]);
      restoreCalendarMonth(calendars[i]);
    }

    document.addEventListener('click', onCalendarClick, false);
  }

  Luxtools.CalendarWidget = {
    init: initCalendarWidgets
  };
})();