/**
 * LLM 论文图书馆 — 前端 JS
 * 页面加载检测 arXiv/HF 连通性 → 底部状态条
 * 点击论文：arXiv 连通? → iframe 直连 arXiv → 5s 超时 → HK 兜底
 * IDM 拦就拦，不额外对抗
 */

const API = '/api';

let modules = {};
let moduleData = {};
let pdfTimeout = null;
let networkStatus = {};

const $  = (sel) => document.querySelector(sel);
const $$ = (sel) => document.querySelectorAll(sel);
const TAG_CLASS = { '起点':'tag-start','关键节点':'tag-milestone','前沿':'tag-frontier','前瞻':'tag-forward','支线':'tag-branch' };

// ══════════════════ INIT ═══════════════════════════════
async function init() {
  buildStatusBar();
  try {
    const resp = await fetch(`${API}/modules`);
    const mods = await resp.json();
    for (const m of mods) modules[m.id] = m;
    renderCards(mods);
    attachGlowTracking();
  } catch (e) { console.error(e); }
  checkSources();
  document.addEventListener('keydown', e => {
    if (e.key === 'Escape') {
      if ($('#pdfOverlay')?.classList.contains('open')) closePdf();
      else if ($('#overlay').classList.contains('open')) closeModal();
    }
  });
}

// ══════════════════ STATUS BAR ════════════════════════
function buildStatusBar() {
  const bar = document.createElement('div');
  bar.id = 'statusBar'; bar.className = 'status-bar';
  bar.innerHTML = `<span class="status-label">连通性检测</span>
    <span class="status-item" id="status-arxiv"><span class="status-dot"></span> arXiv <span class="status-ms" id="ms-arxiv">—</span></span>
    <span class="status-item" id="status-hf"><span class="status-dot"></span> HuggingFace <span class="status-ms" id="ms-hf">—</span></span>`;
  document.body.appendChild(bar);
}

function setStatus(id, ok, ms, aborted) {
  networkStatus[id.replace('status-','')] = ok;
  const el = document.getElementById(id); if (!el) return;
  el.querySelector('.status-dot').className = 'status-dot ' + (ok ? 'status-ok' : 'status-fail');
  const msEl = document.getElementById('ms-'+id.replace('status-',''));
  if (msEl) {
    if (aborted) msEl.textContent = '超时';
    else if (ok) msEl.textContent = ms+'ms';
    else          msEl.textContent = '—';
  }
}

async function checkSource(name, url, statusId) {
  const start = performance.now();
  let aborted = false;
  const probeUrl = url + '?_=' + Date.now();
  try {
    const ctrl = new AbortController();
    setTimeout(() => { aborted = true; ctrl.abort(); }, 4000);
    await fetch(probeUrl, { mode: 'no-cors', signal: ctrl.signal, cache: 'no-store' });
    const ms = Math.round(performance.now() - start);
    setStatus(statusId, true, ms, false);
  } catch {
    const ms = Math.round(performance.now() - start);
    setStatus(statusId, false, ms, aborted);
  }
}

function checkSources() {
  checkSource('arxiv', 'https://arxiv.org/favicon.ico', 'status-arxiv');
  checkSource('hf',   'https://huggingface.co/favicon.ico', 'status-hf');
}

// ══════════════════ GLOW ══════════════════════════════
function attachGlowTracking() {
  $$('.card').forEach(card => {
    card.addEventListener('mousemove', e => {
      const r = card.getBoundingClientRect();
      card.style.setProperty('--mx', (e.clientX-r.left)/r.width*100+'%');
      card.style.setProperty('--my', (e.clientY-r.top)/r.height*100+'%');
    });
  });
}

// ══════════════════ CARDS → MODAL → PAPERS ═══════════
function renderCards(mods) {
  $('#moduleGrid').innerHTML = mods.map(m =>
    `<div class="card card-${m.id}" onclick="openModule('${m.id}')">
      <div class="card-header"><span class="card-icon">${m.icon}</span> ${m.name}</div>
      <div class="card-desc">${m.desc}</div>
      <div class="card-badge">${m.area_count} 子领域 · ${m.paper_count} 篇</div>
    </div>`).join('');
}

async function openModule(modId) {
  let data = moduleData[modId];
  if (!data) {
    try { data = await (await fetch(`${API}/modules/${modId}`)).json(); moduleData[modId]=data; }
    catch { return; }
  }
  const mod = modules[modId];
  $('#modalTitle').innerHTML = `<span class="card-icon">${mod?.icon||''}</span> ${data.name}`;
  $('#modalSubtitle').textContent = data.desc||'';
  const areas = data.areas||[];
  $('#modalTabs').innerHTML = areas.map((a,i)=>`<button class="tab ${i?'':'active'}" onclick="switchArea(${i})">${a.name}</button>`).join('');
  if (areas.length) { $('#modalTabs').dataset.areaIdx='0'; renderPapers(areas[0]); }
  $('#overlay').classList.add('open');
}

function switchArea(idx) {
  const data = Object.values(moduleData).find(d => d.areas && d.areas[idx]);
  if (!data) return;
  $$('#modalTabs .tab').forEach((t,i)=>t.classList.toggle('active',i===idx));
  renderPapers(data.areas[idx]);
}

function closeModal() { $('#overlay').classList.remove('open'); }

function renderPapers(area) {
  const s = (l, ps, c) => ps.length ? `<div class="section-label ${c}">${l}</div>`+ps.map(renderPaper).join('') : '';
  $('#modalContent').innerHTML =
    s('📌 主线论文', area.mainline||[],'mainline') +
    s('🌿 支线论文', area.branches||[],'branch') +
    s('🔮 前瞻探索', area.forward||[],'forward') ||
    '<p style="color:var(--text-dim);padding:20px;">暂无论文数据</p>';
}

function renderPaper(p) {
  const pdfUrl = getPdfLink(p);
  const tags = (p.tags||[]).map(t=>`<span class="paper-tag ${TAG_CLASS[t]||'tag-branch'}">${t}</span>`).join(' ');
  const links = [];
  if (pdfUrl) links.push(`<button class="paper-link" data-pdf="${encodeURIComponent(pdfUrl)}" data-title="${encodeURIComponent(p.title)}" onclick="openPdfBtn(this)">📄 阅读</button>`);
  else if (p.arxiv) links.push(`<a class="paper-link" href="https://arxiv.org/abs/${p.arxiv}" target="_blank">📋 arXiv</a>`);
  return `<div class="paper-item"><div class="paper-year">${p.year||'—'}</div><div class="paper-body">
    <div class="paper-title">${p.title}</div>
    <div class="paper-meta"><span>${p.authors||''}</span>${p.venue?`<span class="paper-venue">${p.venue}</span>`:''}${tags}</div>
    <div class="paper-links">${links.join('')}</div>
  </div></div>`;
}

function getPdfLink(p) {
  // 有 pdf 字段 → 返回外部源 URL（arxiv 直连 / HF 直连）
  if (p.pdf) return p.pdf;
  // 只有 arxiv id → arXiv 直连
  if (p.arxiv) return `https://arxiv.org/pdf/${p.arxiv}.pdf`;
  return null;
}

function openPdfBtn(btn) { openPdf(btn.dataset.pdf, btn.dataset.title); }

// ══════════════════ PDF VIEWER ════════════════════════
function getLocalUrl(extUrl) {
  // arXiv
  const am = extUrl.match(/arxiv\.org\/pdf\/(\d+\.\d+)/);
  if (am) return `/papers/arxiv/${am[1]}.pdf`;
  // HuggingFace
  if (extUrl.includes('huggingface.co')) {
    const name = decodeURIComponent(extUrl).split('/').pop().replace('.pdf','');
    return `/papers/hf/${name}.pdf`;
  }
  return null;
}

function openPdf(url, title) {
  const decodedUrl = decodeURIComponent(url);
  const decodedTitle = decodeURIComponent(title);

  // 构建 overlay
  if (!$('#pdfOverlay')) {
    const div = document.createElement('div'); div.id='pdfOverlay'; div.className='pdf-overlay';
    div.innerHTML = `<div class="pdf-container" id="pdfContainer">
      <div class="pdf-toolbar"><span id="pdfTitle">PDF</span><span id="pdfStatus" style="color:var(--orange);font-size:0.8em;margin-left:8px;"></span>
        <button onclick="window.open($('#pdfFrame').src || currentPdf,'_blank')">🔗 新窗口</button>
        <button class="pdf-close" onclick="closePdf()">&times;</button></div>
      <iframe class="pdf-frame" id="pdfFrame" src=""></iframe></div>`;
    document.body.appendChild(div);
    div.addEventListener('click', e => { if (e.target===div) closePdf(); });
  }

  if (pdfTimeout) { clearTimeout(pdfTimeout); pdfTimeout=null; }
  $('#pdfTitle').textContent = decodedTitle;
  $('#pdfStatus').textContent = '';
  const frame = $('#pdfFrame');
  let loaded = false;
  frame.src = 'about:blank';
  frame.onload = ()=>{ loaded=true; if(pdfTimeout){clearTimeout(pdfTimeout);pdfTimeout=null;} $('#pdfStatus').textContent=''; };

  const hkLocalUrl = getLocalUrl(decodedUrl);
  const isArxiv = decodedUrl.includes('arxiv.org');
  const isHF = decodedUrl.includes('huggingface.co');
  const isRemote = isArxiv || isHF;
  const sourceOk = isArxiv ? networkStatus['arxiv'] !== false
                : isHF     ? networkStatus['hf'] !== false
                : false;

  // 弹框先出
  $('#pdfOverlay').classList.add('open');

  if (isRemote && sourceOk) {
    // 远程源 iframe 直连
    loaded = false;
    $('#pdfStatus').textContent = isArxiv ? '🌐 arXiv 加载中...' : '🤗 HuggingFace 加载中...';
    frame.src = decodedUrl;

    pdfTimeout = setTimeout(() => {
      if (loaded) return;
      if (!hkLocalUrl) { $('#pdfStatus').textContent='⚠️ 超时'; return; }
      $('#pdfStatus').textContent = '⏳ 超时，走 HK 服务器...';
      frame.src = hkLocalUrl;
    }, 5000);
  } else {
    // 直接走 HK
    $('#pdfStatus').textContent = hkLocalUrl ? '📂 HK 服务器加载中...' : '⏳ 加载中...';
    frame.src = hkLocalUrl || decodedUrl;
  }
}

function closePdf() {
  if (pdfTimeout) { clearTimeout(pdfTimeout); pdfTimeout=null; }
  $('#pdfOverlay').classList.remove('open');
  $('#pdfFrame').src = '';
}

// ══════════════════ SEARCH ════════════════════════════
function searchPapers(q) {
  q=(q||'').toLowerCase().trim();
  if (q.length<2) { $$('.card').forEach(c=>c.style.outline=''); return; }
  fetch(`${API}/papers?q=${encodeURIComponent(q)}&limit=10`).then(r=>r.json()).then(ps=>{
    const matched = new Set(ps.map(p=>p.module_id));
    $$('.card').forEach(c=>{
      const m=[...c.classList].find(x=>x.startsWith('card-'))?.replace('card-','');
      c.style.outline=matched.has(m)?'2px solid var(--green)':'';
    });
  });
}

// ══════════════════ EVENTS ════════════════════════════
if (typeof document !== 'undefined') {
  document.addEventListener('DOMContentLoaded', () => {
    init();
    $('.search-input').addEventListener('input', e => searchPapers(e.target.value));
    $('#modalClose').addEventListener('click', closeModal);
    $('#overlay').addEventListener('click', e => { if (e.target===$('#overlay')) closeModal(); });
  });
}