const API = location.origin;
let token = sessionStorage.getItem('adminToken');
function hdr() { return { 'X-Admin-Token': token }; }
function hdrJson() { return { 'Content-Type': 'application/json', 'X-Admin-Token': token }; }
function esc(s) { const d = document.createElement('div'); d.textContent = s; return d.innerHTML; }

// --- Auth check ---
async function checkAuth() {
  if (!token) { location.href = 'login.html'; return false; }
  try {
    const res = await fetch(`${API}/api/stats`, { headers: hdr() });
    if (!res.ok) { sessionStorage.removeItem('adminToken'); location.href = 'login.html'; return false; }
    return true;
  } catch { sessionStorage.removeItem('adminToken'); location.href = 'login.html'; return false; }
}

function doLogout() {
  sessionStorage.removeItem('adminToken');
  location.href = 'login.html';
}

// --- Sidebar ---
const NAV = [
  { page: 'dashboard', label: 'Дашборд' },
  { page: 'journal', label: 'Журнал' },
  { page: 'links', label: 'Ссылки' },
  { page: 'students', label: 'Ученики' },
  { page: 'groups', label: 'Группы' },
  { page: 'settings', label: 'Настройки' }
];
function buildSidebar(active) {
  const el = document.getElementById('sidebar');
  if (!el) return;
  el.innerHTML = `
    <div class="logo">Админ-панель</div>
    <nav>
      ${NAV.map(n => `<a href="${n.page}.html" class="${n.page === active ? 'active' : ''}">${n.label}</a>`).join('')}
    </nav>
    <div class="bottom">
      <a href="/">На главную</a>
      <a class="logout" onclick="doLogout()">Выйти</a>
    </div>`;
}

// --- Common UI ---
function showToast(msg) {
  const t = document.getElementById('toast');
  t.textContent = msg;
  t.classList.add('show');
  setTimeout(() => t.classList.remove('show'), 3000);
}

function showImg(src) {
  const img = document.getElementById('imgModalSrc');
  const m = document.getElementById('imgModal');
  if (img && m) { img.src = src; m.classList.add('open'); }
}

async function fillAutocomplete() {
  const res = await fetch(`${API}/api/students`);
  const students = await res.json();
  const names = students.map(s => s.name);
  const dlEdit = document.getElementById('studentEditList');
  if (dlEdit) {
    dlEdit.innerHTML = '';
    names.forEach(n => { const o = document.createElement('option'); o.value = n; dlEdit.appendChild(o); });
  }
  const dlAdd = document.getElementById('studentAddList');
  if (dlAdd) {
    dlAdd.innerHTML = '';
    names.forEach(n => { const o = document.createElement('option'); o.value = n; dlAdd.appendChild(o); });
  }
}

function copyStudentLink(name) {
  const url = `${location.origin}/?nameInput=${encodeURIComponent(name)}`;
  const done = () => showToast('Ссылка скопирована: ' + url);
  if (navigator.clipboard && window.isSecureContext) {
    navigator.clipboard.writeText(url).then(done).catch(() => fallbackCopy(url, done));
  } else {
    fallbackCopy(url, done);
  }
}

function fallbackCopy(text, done) {
  const ta = document.createElement('textarea');
  ta.value = text;
  ta.style.position = 'fixed';
  ta.style.opacity = '0';
  document.body.appendChild(ta);
  ta.select();
  try { document.execCommand('copy'); done(); } catch { prompt('Скопируйте вручную:', text); }
  document.body.removeChild(ta);
}

function copyText(text) {
  const done = () => showToast('Скопировано: ' + text);
  if (navigator.clipboard && window.isSecureContext) {
    navigator.clipboard.writeText(text).then(done).catch(() => fallbackCopy(text, done));
  } else {
    fallbackCopy(text, done);
  }
}

function renderPager(el, page, totalPages, onPage) {
  if (!el) return;
  if (totalPages <= 1) { el.innerHTML = ''; return; }
  let html = `<button ${page === 1 ? 'disabled' : ''} onclick="(${onPage})(${page - 1})">‹</button>`;
  for (let i = 1; i <= totalPages; i++) {
    if (totalPages > 9 && i > 2 && i < totalPages - 1 && Math.abs(i - page) > 2) {
      if (i === 3) html += `<button disabled>…</button>`;
      continue;
    }
    html += `<button class="${i === page ? 'active' : ''}" onclick="(${onPage})(${i})">${i}</button>`;
  }
  html += `<button ${page === totalPages ? 'disabled' : ''} onclick="(${onPage})(${page + 1})">›</button>`;
  el.innerHTML = html;
}