// Shared timetable group form view-model builder.

const { normalizeTimeZone } = require('../../../../data/timetables');

const COMMON_TIME_ZONES = [
  'UTC',
  'Europe/London',
  'Europe/Dublin',
  'Europe/Paris',
  'Europe/Berlin',
  'Europe/Madrid',
  'America/New_York',
  'America/Chicago',
  'America/Denver',
  'America/Los_Angeles',
  'America/Toronto',
  'America/Vancouver',
  'America/Sao_Paulo',
  'Asia/Dubai',
  'Asia/Kolkata',
  'Asia/Singapore',
  'Asia/Tokyo',
  'Asia/Seoul',
  'Australia/Sydney',
  'Pacific/Auckland'
];

function buildDefaultTimetableGroup() {
  return {
    id: null,
    name: '',
    shortDescription: '',
    timezone: 'Europe/London'
  };
}

function formatDateTimeLocalValue(value, timeZone) {
  if (!value) {
    return '';
  }

  const date = new Date(value);
  if (Number.isNaN(date.getTime())) {
    return '';
  }

  const resolvedTimeZone = normalizeTimeZone(timeZone, 'Europe/London');
  const parts = new Intl.DateTimeFormat('en-GB', {
    timeZone: resolvedTimeZone,
    hour12: false,
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit',
    second: '2-digit'
  }).formatToParts(date).reduce(function (acc, part) {
    if (part && part.type && part.type !== 'literal') {
      acc[part.type] = part.value;
    }
    return acc;
  }, Object.create(null));

  if (!parts.year || !parts.month || !parts.day || !parts.hour || !parts.minute) {
    return '';
  }

  return [
    String(parts.year).padStart(4, '0'),
    '-',
    String(parts.month).padStart(2, '0'),
    '-',
    String(parts.day).padStart(2, '0'),
    'T',
    String(parts.hour).padStart(2, '0'),
    ':',
    String(parts.minute).padStart(2, '0')
  ].join('');
}

function buildTimetableGroupFormViewModel(timetableGroup, timetableEntries, message, currentUser, isEdit, options) {
  const viewTimetableGroup = Object.assign(buildDefaultTimetableGroup(), timetableGroup || {});
  viewTimetableGroup.timezone = normalizeTimeZone(viewTimetableGroup.timezone, 'Europe/London');
  const viewOptions = options || {};
  const viewTimetableEntries = Array.isArray(timetableEntries) && timetableEntries.length
    ? timetableEntries.map(function (entry) {
        return Object.assign({}, entry, {
          startValue: formatDateTimeLocalValue(entry.start_datetime, viewTimetableGroup.timezone),
          endValue: formatDateTimeLocalValue(entry.end_datetime, viewTimetableGroup.timezone)
        });
      })
    : [{ id: null, title: '', short_description: '', startValue: '', endValue: '', sort_order: 0 }];

  return {
    title: isEdit ? 'Edit timetable group' : 'Add timetable group',
    active: 'timetables',
    message: message,
    currentUser: currentUser || null,
    messageVariant: viewOptions.messageVariant || '',
    isEdit: Boolean(isEdit),
    timetableGroup: viewTimetableGroup,
    timeZoneOptions: COMMON_TIME_ZONES,
    timetableEntries: viewTimetableEntries,
    inUse: Boolean(viewTimetableGroup.inUse),
    showSaveSecondaryActions: true,
    cancelConfirmMessage: "You've made changes. Are you sure you want to leave this page?",
    deleteConfirmMessage: isEdit ? 'Delete this timetable group?' : '',
    deleteDisabled: !isEdit || Boolean(viewTimetableGroup.inUse),
    formAction: isEdit && viewTimetableGroup.id ? '/data-sources/timetables/' + viewTimetableGroup.id : '/data-sources/timetables',
    formAttrs: 'data-async-save' + (isEdit ? ' data-async-save-close-url="/data-sources/timetables"' : ' data-async-save-new-redirect="response-url"') + ' data-async-save-new-url="/data-sources/timetables/new"',
    cancelUrl: '/data-sources/timetables',
    deleteUrl: isEdit && viewTimetableGroup.id ? '/data-sources/timetables/' + viewTimetableGroup.id + '/delete' : '',
    assetVersion: Date.now().toString(36)
  };
}

module.exports = {
  buildTimetableGroupFormViewModel: buildTimetableGroupFormViewModel
};