// 联系人自动补全模块
const _acCache = {};

async function acFetchNames(field) {
  if (_acCache[field] && Date.now() - _acCache[field].ts < 60000) return _acCache[field].data;
  try {
    const res = await fetch(API + '/api/contacts?field=' + field, { headers: headers() });
    if (!res.ok) return [];
    const data = await res.json();
    _acCache[field] = { data, ts: Date.now() };
    return data;
  } catch { return []; }
}

function acInvalidateCache(field) {
  if (field) delete _acCache[field];
  else Object.keys(_acCache).forEach(k => delete _acCache[k]);
}

function acSetup(inputId, field) {
  const input = document.getElementById(inputId);
  if (!input || input._acBound) return;
  input._acBound = true;
  input.setAttribute('autocomplete', 'off');

  const wrap = document.createElement('div');
  wrap.className = 'ac-wrap';
  input.parentNode.insertBefore(wrap, input);
  wrap.appendChild(input);

  const list = document.createElement('div');
  list.className = 'ac-list';
  wrap.appendChild(list);

  let names = [];
  let activeIdx = -1;

  async function loadNames() {
    names = await acFetchNames(field);
  }

  function render(query) {
    const q = query.trim().toLowerCase();
    const filtered = q ? names.filter(n => n.toLowerCase().includes(q)) : names;
    if (filtered.length === 0) { list.classList.remove('show'); return; }
    activeIdx = -1;
    list.innerHTML = filtered.slice(0, 10).map((n, i) => {
      let display = n;
      if (q) {
        const idx = n.toLowerCase().indexOf(q);
        if (idx >= 0) {
          display = n.slice(0, idx) + '<span class="ac-highlight">' + n.slice(idx, idx + q.length) + '</span>' + n.slice(idx + q.length);
        }
      }
      return `<div class="ac-item" data-idx="${i}" data-value="${n.replace(/"/g, '&quot;')}">${display}</div>`;
    }).join('');
    list.classList.add('show');
  }

  function pick(value) {
    input.value = value;
    list.classList.remove('show');
    input.dispatchEvent(new Event('input', { bubbles: true }));
  }

  input.addEventListener('focus', async () => {
    await loadNames();
    render(input.value);
  });

  input.addEventListener('input', () => { render(input.value); });

  input.addEventListener('keydown', (e) => {
    const items = list.querySelectorAll('.ac-item');
    if (!list.classList.contains('show') || items.length === 0) return;
    if (e.key === 'ArrowDown') {
      e.preventDefault();
      activeIdx = Math.min(activeIdx + 1, items.length - 1);
      items.forEach((el, i) => el.classList.toggle('active', i === activeIdx));
      items[activeIdx].scrollIntoView({ block: 'nearest' });
    } else if (e.key === 'ArrowUp') {
      e.preventDefault();
      activeIdx = Math.max(activeIdx - 1, 0);
      items.forEach((el, i) => el.classList.toggle('active', i === activeIdx));
      items[activeIdx].scrollIntoView({ block: 'nearest' });
    } else if (e.key === 'Enter' && activeIdx >= 0) {
      e.preventDefault();
      pick(items[activeIdx].dataset.value);
    } else if (e.key === 'Escape') {
      list.classList.remove('show');
    }
  });

  list.addEventListener('mousedown', (e) => {
    e.preventDefault(); // 防止 input 失焦
    const item = e.target.closest('.ac-item');
    if (item) pick(item.dataset.value);
  });

  document.addEventListener('click', (e) => {
    if (!wrap.contains(e.target)) list.classList.remove('show');
  });
}