// 数据模型与工具
const Models = (function () {
  function uuid() {
    return (crypto && crypto.randomUUID) ? crypto.randomUUID() : (
      Date.now() + '-' + Math.random().toString(36).slice(2)
    );
  }

  function nowISO() { return new Date().toISOString(); }

  function ensureEnd(startISO, endISO, allDay) {
    if (endISO) return endISO;
    const s = new Date(startISO);
    const e = new Date(s.getTime() + (allDay ? 24 * 3600_000 : 60 * 60_000));
    return e.toISOString();
  }

  function createEvent({ title, content, start, end, allDay, remindAt, recurrence, completed }) {
    const createdAt = nowISO();
    const ev = {
      id: uuid(),
      title: (title || '').trim(),
      content: (content || '').trim(),
      start,
      end: ensureEnd(start, end, !!allDay),
      allDay: !!allDay,
      remindAt: remindAt || '',
      recurrence: recurrence || '',
      completed: !!completed,
      createdAt,
      updatedAt: createdAt,
      deleted: false,
    };
    return ev;
  }

  function normalizeForUpdate(ev) {
    ev.updatedAt = nowISO();
    if (!ev.end) ev.end = ensureEnd(ev.start, ev.end, ev.allDay);
    ev.title = (ev.title || '').trim();
    ev.content = (ev.content || '').trim();
    ev.completed = !!ev.completed;
    return ev;
  }

  function isSameDay(isoA, isoB) {
    const a = new Date(isoA), b = new Date(isoB);
    return a.getUTCFullYear() === b.getUTCFullYear() &&
           a.getUTCMonth() === b.getUTCMonth() &&
           a.getUTCDate() === b.getUTCDate();
  }

  return { createEvent, normalizeForUpdate, isSameDay };
})();

window.Models = Models;