(function () {
  'use strict';

  let csrfToken = '';

  async function fetchCsrfToken() {
    const res = await fetch('/api/csrf-token', { credentials: 'same-origin' });
    if (!res.ok) throw new Error('Failed to fetch CSRF token');
    const data = await res.json();
    csrfToken = data.csrfToken;
    return csrfToken;
  }

  function csrfHeaders(base = {}) {
    return { ...base, 'x-csrf-token': csrfToken };
  }

  function showToast(message, type = 'success') {
    const toast = document.createElement('div');
    toast.className = `toast toast-${type}`;
    toast.textContent = message;
    document.getElementById('toast-container').appendChild(toast);
    setTimeout(() => toast.remove(), 3500);
  }

  function formatLocalDateTime(d) {
    const pad = n => String(n).padStart(2, '0');
    return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`;
  }

  const MOBILE_BREAKPOINT = 900;

  function isMobileViewport() {
    return window.innerWidth <= MOBILE_BREAKPOINT;
  }

  function setSidebarOpen(open) {
    document.body.classList.toggle('sidebar-open', open);
    const toggle = document.getElementById('menu-toggle');
    if (toggle) toggle.setAttribute('aria-expanded', String(open));
  }

  window.Util = {
    fetchCsrfToken,
    csrfHeaders,
    showToast,
    formatLocalDateTime,
    isMobileViewport,
    setSidebarOpen,
    MOBILE_BREAKPOINT
  };
})();