(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 isError = type === 'error';
    const timeoutMs = isError ? 6000 : 3500;

    const toast = document.createElement('div');
    toast.className = `toast toast-${type}`;
    // status (polite) for info/success/warning; alert (assertive) for errors.
    toast.setAttribute('role', isError ? 'alert' : 'status');
    toast.setAttribute('aria-live', isError ? 'assertive' : 'polite');
    toast.setAttribute('aria-atomic', 'true');

    const messageEl = document.createElement('span');
    messageEl.className = 'toast-message';
    messageEl.textContent = message;
    toast.appendChild(messageEl);

    const closeBtn = document.createElement('button');
    closeBtn.type = 'button';
    closeBtn.className = 'toast-close';
    closeBtn.setAttribute('aria-label', 'Dismiss');
    closeBtn.textContent = '×';
    toast.appendChild(closeBtn);

    // Auto-dismiss with hover-to-pause.
    let remaining = timeoutMs;
    let startedAt = 0;
    let timer = null;

    function dismiss() {
      if (timer) clearTimeout(timer);
      timer = null;
      if (toast.parentNode) toast.remove();
    }

    function scheduleDismiss() {
      startedAt = Date.now();
      timer = setTimeout(dismiss, remaining);
    }

    function pauseDismiss() {
      if (!timer) return;
      clearTimeout(timer);
      timer = null;
      remaining -= Date.now() - startedAt;
    }

    closeBtn.addEventListener('click', dismiss);
    toast.addEventListener('mouseenter', pauseDismiss);
    toast.addEventListener('mouseleave', scheduleDismiss);
    toast.addEventListener('focusin', pauseDismiss);
    toast.addEventListener('focusout', scheduleDismiss);

    document.getElementById('toast-container').appendChild(toast);
    scheduleDismiss();
  }

  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));
  }

  // ---------- Modal focus management ----------

  const FOCUSABLE_SELECTOR = [
    'a[href]',
    'button:not([disabled])',
    'input:not([disabled]):not([type="hidden"])',
    'select:not([disabled])',
    'textarea:not([disabled])',
    '[tabindex]:not([tabindex="-1"])'
  ].join(',');

  function getFocusableElements(container) {
    return Array.from(container.querySelectorAll(FOCUSABLE_SELECTOR))
      .filter(el => !el.hasAttribute('inert') && el.offsetParent !== null);
  }

  // Per-modal teardown state; WeakMap keys by modal element to support many.
  const modalState = new WeakMap();

  function openModal(modalEl, options = {}) {
    if (!modalEl) return;
    if (modalState.has(modalEl)) return; // already open

    const previouslyFocused = document.activeElement;
    modalEl.classList.remove('hidden');

    // Find something to focus. Prefer options.initialFocus, then first field, then modal card.
    const card = modalEl.querySelector('.modal-card') || modalEl;
    if (!card.hasAttribute('tabindex')) card.setAttribute('tabindex', '-1');
    const initial = options.initialFocus
      ? modalEl.querySelector(options.initialFocus)
      : getFocusableElements(modalEl)[0] || card;
    initial?.focus();

    const onKeydown = (e) => {
      if (e.key === 'Escape') {
        e.preventDefault();
        closeModal(modalEl);
        options.onClose?.();
        return;
      }
      if (e.key !== 'Tab') return;
      const focusables = getFocusableElements(modalEl);
      if (focusables.length === 0) {
        e.preventDefault();
        card.focus();
        return;
      }
      const first = focusables[0];
      const last = focusables[focusables.length - 1];
      if (e.shiftKey && document.activeElement === first) {
        e.preventDefault();
        last.focus();
      } else if (!e.shiftKey && document.activeElement === last) {
        e.preventDefault();
        first.focus();
      }
    };
    modalEl.addEventListener('keydown', onKeydown);

    modalState.set(modalEl, { previouslyFocused, onKeydown });
  }

  function closeModal(modalEl) {
    if (!modalEl) return;
    const state = modalState.get(modalEl);
    modalEl.classList.add('hidden');
    if (!state) return;
    modalEl.removeEventListener('keydown', state.onKeydown);
    modalState.delete(modalEl);
    const target = state.previouslyFocused;
    if (target && typeof target.focus === 'function' && document.body.contains(target)) {
      target.focus();
    } else {
      document.body.focus?.();
    }
  }

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