// doc/page_utils.js
// Small helpers shared by documentation demo pages (3rd column).

(function () {
  function qs(sel) { return document.querySelector(sel); }
  function qsa(sel) { return Array.from(document.querySelectorAll(sel)); }

  function showToast(msg) {
    const el = document.getElementById('toast');
    if (!el) return;
    el.textContent = msg;
    el.classList.add('show');
    clearTimeout(el._t);
    el._t = setTimeout(() => el.classList.remove('show'), 900);
  }

  async function copyActiveCode() {
    const active = qs('.code-view.active, .html-view.active, .css-view.active');
    const text = active ? active.innerText.trimEnd() : '';
    if (!text) return;
    try {
      await navigator.clipboard.writeText(text);
      showToast('Copied');
    } catch (e) {
      // Fallback
      const ta = document.createElement('textarea');
      ta.value = text;
      ta.style.position = 'fixed';
      ta.style.opacity = '0';
      document.body.appendChild(ta);
      ta.select();
      document.execCommand('copy');
      ta.remove();
      showToast('Copied');
    }
  }

  function switchTab(tab) {
    const tabs = qsa('.tabs .tab');
    tabs.forEach(t => t.classList.remove('active'));
    qsa('.code-view, .html-view, .css-view').forEach(v => v.classList.remove('active'));

    const t = String(tab || 'js').toLowerCase();
    const idx = (t === 'js') ? 0 : (t === 'html') ? 1 : 2;
    const tabEls = [tabs[0], tabs[1], tabs[2]];
    const viewEls = [
      document.getElementById('js-code'),
      document.getElementById('html-code'),
      document.getElementById('css-code')
    ];

    tabEls.forEach((el, i) => {
      if (!el) return;
      const active = i === idx;
      el.classList.toggle('active', active);
      el.setAttribute('aria-selected', active ? 'true' : 'false');
      el.tabIndex = active ? 0 : -1;
    });
    const view = viewEls[idx];
    if (view) view.classList.add('active');
  }

  function enableTabKeyboardNav() {
    document.addEventListener('keydown', (e) => {
      const focused = document.activeElement;
      if (!focused || !focused.classList.contains('tab')) return;
      if (e.key !== 'ArrowLeft' && e.key !== 'ArrowRight') return;
      e.preventDefault();

      const tabs = qsa('.tabs .tab');
      const idx = Math.max(0, tabs.indexOf(focused));
      const nextIdx = (e.key === 'ArrowRight')
        ? (idx + 1) % tabs.length
        : (idx - 1 + tabs.length) % tabs.length;
      const next = tabs[nextIdx];
      const label = (next?.textContent || '').toLowerCase();
      const lang = label.includes('html') ? 'html' : label.includes('css') ? 'css' : 'js';
      switchTab(lang);
      qs('.tab.active')?.focus();
    });
  }

  function syncPrevNext(currentUrl) {
    try {
      const pn = window.parent?.docGetPrevNext?.(currentUrl);
      const prevEl = document.getElementById('prev-title');
      const nextEl = document.getElementById('next-title');
      const centerEl = document.getElementById('nav-center');
      if (centerEl) centerEl.textContent = pn?.current?.group || centerEl.textContent || '';
      if (prevEl) prevEl.textContent = pn?.prev?.title || '—';
      if (nextEl) nextEl.textContent = pn?.next?.title || '—';
    } catch {}
  }

  function syncMiddleActive(currentUrl) {
    try { window.parent?.setMiddleActive?.(currentUrl); } catch {}
  }

  // Expose
  window.DocPage = {
    showToast,
    copyActiveCode,
    switchTab,
    enableTabKeyboardNav,
    syncPrevNext,
    syncMiddleActive
  };
}());