'use strict';

/* ── tiny DOM helpers ─────────────────────────────────────── */
const $  = (sel, el = document) => el.querySelector(sel);
const $$ = (sel, el = document) => Array.from(el.querySelectorAll(sel));

const _post = (url, body) => fetch(url, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify(body),
}).then(async r => {
  if (!r.ok) {
    const j = await r.json().catch(() => ({ detail: r.statusText }));
    throw new Error(j.detail || `HTTP ${r.status}`);
  }
  return r.json();
});

const API = {
  meta:               ()     => fetch('/api/meta').then(r => r.json()),
  tensions:           ()     => fetch('/api/tensions').then(r => r.json()),
  rules:              ()     => fetch('/api/rules').then(r => r.json()),
  generate:           (body) => _post('/api/generate', body),
  productFromPrompt:  (body) => _post('/api/products/from_prompt', body),
  tensionFromPrompt:  (body) => _post('/api/tensions/from_prompt', body),
};

/* ── Persona presets — bright, varied, ad-friendly ─────────── */
const PERSONA_PRESETS = {
  newbie:        '첫 출근하는 25세 신입사원, 두근거림과 설렘',
  family:        '35세 부모, 아이와 함께하는 따뜻한 주말 일상',
  student:       '20세 대학생, 친구들과 도전하는 새 학기 첫 주',
  couple:        '신혼부부, 새 집에서 함께 만드는 첫 아침',
  friends:       '친구 4명, 오랜만에 모인 옥상 파티의 활기',
  solo:          '40대 1인 가구, 혼자만의 평온한 저녁 루틴',
  travel:        '28세 직장인, 첫 해외 여행 공항 게이트의 두근거림',
  senior:        '60대 어르신, 매일 동네에서 발견하는 작은 기쁨',
  parent_baby:   '30대 신생아 부모, 첫 아기와의 따뜻한 새벽',
  entrepreneur:  '32세 창업가, 첫 매출의 환희와 다음 도전',
  hobby:         '취미를 시작한 45세, 처음 만든 작품 앞의 미소',
  reunion:       '10년 만에 재회한 동창들, 다시 만난 반가움',
};

/* ── Preset prompt strings ─────────────────────────────────── */
const PROMPT_PRESETS = {
  watch:    '아날로그 손목시계 AETHER-A · 용두, 초침, 사파이어 크리스탈, 방수, 가죽 스트랩',
  coffee:   '수제 로스팅 원두 커피 NOVA-Bean · 원두, 그라인더, 필터, 추출수, 세라믹 잔',
  phone:    '스마트폰 AETHER-Phone · OLED 디스플레이, 트리플 카메라, 배터리, AI 칩셋, 진동모터',
  sneaker:  '러닝화 PULSE-Run · 미드솔 폼, 아웃솔 고무, 니트 어퍼, 레이스, TPU 뒤꿈치컵',
  beer:     '수제 IPA 맥주 HOP-Haru · 갈색 병, 크라운 캡, 헤드 거품, 라벨, 홉',
  cosmetic: '스킨케어 앰플 GLOW-Han · 유리 스포이드, 갈색 자외선 병, 세럼, 한방 허브 향, 한지 박스',
  car:      '전기차 SPIRA-EV · 바닥 배터리팩, 듀얼 마그넷 모터, 17인치 스크린, 요크 핸들, 800V 충전포트',
  laundry:  'O2O 프리미엄 세탁 서비스 MOON-Fold · 수거기사, 앱 실시간 알림, 비닐 커버, 향기 캡슐, 옷걸이',
  edu:      '온라인 코딩 부트캠프 CODE-Muze · 영상 강의, 과제 피드백, 1:1 코드리뷰, 슬랙 방, 수료증',
  banking:  '모바일 은행 앱 HANA-Flow · 홈 화면 위젯, 송금 버튼, 생체 인증, 알림 배너, 챗봇',
};

/* ── State ─────────────────────────────────────────────────── */
let TENSIONS = [];
let CHARTS = [];
let PIPELINE_TIMER = null;
let CURRENT_PRODUCT = null;    // {product_id, brand, category, atoms, ...}
let LAST_PRODUCT_PROMPT = null;
let CURRENT_TENSION = null;    // {id, name, greimas_square, emotional_payoff, description}
let LAST_TENSION_KEY = null;   // string — either preset id or "custom:<prompt>"
let LATEST_RESULTS = null;     // raw /api/generate result — for media handlers
let HAS_FAL = false;           // set from /api/meta
const MEDIA_STATE = {};        // MEDIA_STATE[seedIdx][beatIdx] = {image_url?, video_url?, status, message}

/* ── Boot ──────────────────────────────────────────────────── */
document.addEventListener('DOMContentLoaded', () => {
  try {
    wireInputs();
  } catch (e) {
    console.error('wireInputs failed:', e);
    showGlobalError(`초기화 실패: ${e.message || e}. 브라우저를 하드 리프레시하세요 (Ctrl+Shift+R).`);
  }
  Promise.all([loadMeta(), loadTensions(), loadRules()]).catch(e => {
    console.error('initial loads failed:', e);
  });
});

async function loadMeta() {
  try {
    const m = await API.meta();
    const vEl = $('#version'); if (vEl) vEl.textContent = m.version;
    const sel = $('#backendSel');
    if (!sel) return;
    sel.querySelectorAll('option').forEach(o => {
      if (o.value === 'claude' && !m.has_anthropic_key) {
        o.disabled = true; o.textContent += ' (no key)';
      }
      if (o.value === 'fireworks' && !m.has_fireworks_key) {
        o.disabled = true; o.textContent += ' (no key)';
      }
      if (o.value === 'hf' && !m.has_hf_token) {
        o.disabled = true; o.textContent += ' (no token)';
      }
    });
    sel.value = m.default_backend || 'claude';
    HAS_FAL = !!m.has_fal_key;
    syncBackendPlaceholder();
  } catch (e) { console.error('meta failed', e); }
}

async function loadTensions() {
  TENSIONS = await API.tensions();
  // Auto-select first tension as default without requiring user action
  if (!CURRENT_TENSION && TENSIONS.length > 0) {
    setTension(TENSIONS[0], TENSIONS[0].id);
  }
}

async function loadRules() {
  const rules = await API.rules();
  const rows = [
    `<div class="rule-row header">
       <div>rule_id</div><div>name</div><div>pattern</div><div>theoretical_anchor</div>
     </div>`,
  ];
  rules.forEach(r => {
    rows.push(`
      <div class="rule-row">
        <div class="rule-id">${r.rule_id}</div>
        <div><strong>${escapeHtml(r.name)}</strong></div>
        <div>${escapeHtml(r.pattern)}</div>
        <div class="rule-anchor">${escapeHtml(r.theoretical_anchor)}</div>
      </div>`);
  });
  const tbl = $('#rulesTable');
  if (tbl) tbl.innerHTML = rows.join('');
}

/* ── Wire up inputs defensively — any single null never breaks the rest ─ */
function wireInputs() {
  safeOn('#nSeeds', 'input', e => {
    const out = $('#nSeedsVal'); if (out) out.textContent = e.target.value;
  });
  safeOn('#topK', 'input', e => {
    const out = $('#topKVal'); if (out) out.textContent = e.target.value;
  });
  safeOn('#backendSel', 'change', syncBackendPlaceholder);
  safeOn('#genBtn', 'click', runGenerate);

  safeOn('#productPrompt', 'input', () => {
    if (!$('#productPrompt')) return;
    if ($('#productPrompt').value.trim() !== LAST_PRODUCT_PROMPT) {
      setStatus('#productStatus', 'idle', 'Generate를 누르면 Kimi-K2P6가 genome을 확장합니다.');
    }
  });

  safeOn('#tensionPrompt', 'input', () => {
    const val = $('#tensionPrompt').value.trim();
    if (!val) {
      setStatus('#tensionStatus', 'idle', '프리셋을 클릭하거나 텍스트를 입력하세요.');
      return;
    }
    const key = 'custom:' + val;
    if (key !== LAST_TENSION_KEY) {
      setStatus('#tensionStatus', 'idle', 'Generate 시 자유 입력을 Greimas 사각형으로 확장합니다.');
      // Clear current tension preview until expanded
      if (CURRENT_TENSION && LAST_TENSION_KEY && LAST_TENSION_KEY.startsWith('custom:')) {
        hideGreimasPreview();
      }
    }
  });

  $$('.product-presets .preset-chip-inline').forEach(btn => {
    btn.addEventListener('click', () => {
      const key = btn.dataset.preset;
      const val = PROMPT_PRESETS[key];
      const ta = $('#productPrompt');
      if (val && ta) {
        ta.value = val;
        ta.dispatchEvent(new Event('input'));
        ta.focus();
      }
    });
  });

  $$('.tension-presets .preset-chip-inline').forEach(btn => {
    btn.addEventListener('click', () => {
      const id = btn.dataset.tension;
      const t = TENSIONS.find(x => x.id === id);
      if (!t) return;
      // Clear the textarea so the preset takes priority
      const ta = $('#tensionPrompt'); if (ta) ta.value = '';
      setTension(t, id);
    });
  });

  $$('.persona-presets .preset-chip-inline').forEach(btn => {
    btn.addEventListener('click', () => {
      const key = btn.dataset.persona;
      const val = PERSONA_PRESETS[key];
      const ta = $('#personaIn');
      if (val && ta) { ta.value = val; ta.focus(); }
    });
  });
}

function safeOn(selector, ev, handler) {
  const el = $(selector);
  if (!el) { console.warn('element missing:', selector); return; }
  el.addEventListener(ev, handler);
}

function syncBackendPlaceholder() {
  const v = $('#backendSel') ? $('#backendSel').value : 'claude';
  const placeholders = {
    claude:    'claude-sonnet-4-6',
    fireworks: 'accounts/fireworks/models/kimi-k2p6',
    hf:        'Qwen/Qwen2.5-72B-Instruct',
    none:      '(not used)',
  };
  if ($('#modelIn')) $('#modelIn').placeholder = placeholders[v] || '';
}

/* ── Tension handling ─────────────────────────────────────── */
function setTension(t, key) {
  CURRENT_TENSION = t;
  LAST_TENSION_KEY = key;
  renderGreimasPreview(t);
  setStatus('#tensionStatus', 'ready',
    `✓ <strong>${escapeHtml(t.name)}</strong> · ${escapeHtml(t.emotional_payoff || '')}`);
}

function renderGreimasPreview(t) {
  if (!t || !t.greimas_square) return;
  const sq = t.greimas_square;
  const preview = $('#tensionPreview');
  if (preview) preview.hidden = false;
  if ($('[data-pos="s1"]'))  $('[data-pos="s1"]').textContent  = sq.S1;
  if ($('[data-pos="s2"]'))  $('[data-pos="s2"]').textContent  = sq.S2;
  if ($('[data-pos="ns1"]')) $('[data-pos="ns1"]').textContent = sq.not_S1;
  if ($('[data-pos="ns2"]')) $('[data-pos="ns2"]').textContent = sq.not_S2;
  const payoff = $('#tensionPayoff');
  if (payoff) {
    payoff.innerHTML =
      `${escapeHtml(t.description || '')}<br/><strong>payoff:</strong> ${escapeHtml(t.emotional_payoff || '')}`;
  }
}

function hideGreimasPreview() {
  const preview = $('#tensionPreview');
  if (preview) preview.hidden = true;
}

async function ensureTensionReady() {
  const customText = $('#tensionPrompt') ? $('#tensionPrompt').value.trim() : '';
  // Priority: if user typed custom text, use it (overrides any preset)
  if (customText) {
    const key = 'custom:' + customText;
    if (CURRENT_TENSION && LAST_TENSION_KEY === key) return CURRENT_TENSION;
    const backend = $('#backendSel').value === 'none' ? 'fireworks' : $('#backendSel').value;
    setStatus('#tensionStatus', 'loading', '🧬 Kimi-K2P6가 Greimas 사각형으로 확장 중… (10~20초)');
    try {
      const t = await API.tensionFromPrompt({ prompt: customText, backend });
      setTension(t, key);
      return t;
    } catch (e) {
      setStatus('#tensionStatus', 'error', `❌ ${escapeHtml(e.message || String(e))}`);
      throw e;
    }
  }
  if (CURRENT_TENSION) return CURRENT_TENSION;
  throw new Error('긴장 상황을 선택하거나 입력하세요.');
}

/* ── Product handling ─────────────────────────────────────── */
async function ensureProductReady() {
  const text = $('#productPrompt') ? $('#productPrompt').value.trim() : '';
  if (!text) throw new Error('제품 또는 서비스 설명을 입력하세요.');
  if (CURRENT_PRODUCT && LAST_PRODUCT_PROMPT === text) return CURRENT_PRODUCT;

  const backend = $('#backendSel').value === 'none' ? 'fireworks' : $('#backendSel').value;
  setStatus('#productStatus', 'loading', '🧬 Kimi-K2P6가 genome을 확장 중… (30~60초)');

  try {
    const product = await API.productFromPrompt({ prompt: text, backend });
    CURRENT_PRODUCT = product;
    LAST_PRODUCT_PROMPT = text;
    const atoms = (product.atoms || []).map(a => a.name).join(' · ');
    setStatus('#productStatus', 'ready',
      `✓ <strong>${escapeHtml(product.brand)}</strong> · ${escapeHtml(product.category)} · ${product.atom_count} atoms` +
      (atoms ? `<br/><span style="color: var(--text-subtle); font-size: 11px;">${escapeHtml(atoms)}</span>` : '')
    );
    return product;
  } catch (e) {
    setStatus('#productStatus', 'error', `❌ ${escapeHtml(e.message || String(e))}`);
    throw e;
  }
}

/* ── Generate ─────────────────────────────────────────────── */
async function runGenerate() {
  // ── Synchronous visual feedback FIRST (before any await).
  //    Without this, user sees NO change for a few ms after click,
  //    so they think the button is broken.
  setRunning(true);
  const err = $('#errBox'); if (err) { err.hidden = true; err.textContent = ''; }
  const empty = $('#emptyState'); if (empty) empty.style.display = 'none';
  animatePipeline();

  // Also immediately reflect prep state in the status dots
  if (!$('#productPrompt').value.trim()) {
    // Nothing to expand — will fail validation below, but show prep status anyway
    setStatus('#productStatus', 'loading', '⏳ 입력 확인 중…');
  } else if (!CURRENT_PRODUCT || LAST_PRODUCT_PROMPT !== $('#productPrompt').value.trim()) {
    setStatus('#productStatus', 'loading', '🧬 genome 확장 준비 중…');
  }
  if ($('#tensionPrompt').value.trim() &&
      (LAST_TENSION_KEY !== 'custom:' + $('#tensionPrompt').value.trim())) {
    setStatus('#tensionStatus', 'loading', '🧬 Greimas 사각형 준비 중…');
  }

  let tension, product;
  try {
    tension = await ensureTensionReady();
  } catch (e) {
    resetPipeline();
    showGlobalError(`❌ ${e.message || e}`);
    setRunning(false);
    if ($('#summaryBar') && $('#summaryBar').hidden && empty) empty.style.display = '';
    return;
  }
  try {
    product = await ensureProductReady();
  } catch (e) {
    resetPipeline();
    showGlobalError(`❌ ${e.message || e}`);
    setRunning(false);
    if ($('#summaryBar') && $('#summaryBar').hidden && empty) empty.style.display = '';
    return;
  }

  const durInput = $$('input[name="duration"]').find(r => r.checked);
  const body = {
    product_id: product.product_id,
    tension_id: tension.id,
    persona:    ($('#personaIn') && $('#personaIn').value.trim()) || '일반 소비자',
    duration:   durInput ? parseInt(durInput.value, 10) : 15,
    n_seeds:    $('#nSeeds') ? parseInt($('#nSeeds').value, 10) : 5,
    top_k:      $('#topK')   ? parseInt($('#topK').value, 10)   : 3,
    backend:    $('#backendSel').value,
    model:      ($('#modelIn') && $('#modelIn').value.trim()) || null,
    rng_seed:   $('#rngSeed') ? parseInt($('#rngSeed').value || '42', 10) : 42,
  };

  try {
    const r = await API.generate(body);
    completePipeline();
    renderResults(r);
  } catch (e) {
    resetPipeline();
    const msg = e && e.message ? e.message : String(e);
    showGlobalError(`❌ ${msg}`);
    if ($('#summaryBar') && $('#summaryBar').hidden && empty) empty.style.display = '';
    console.error(e);
  } finally {
    setRunning(false);
  }
}

function showGlobalError(msg) {
  const box = $('#errBox');
  if (box) { box.hidden = false; box.textContent = msg; }
  else     { alert(msg); }
}

function setStatus(sel, kind, html) {
  const box = $(sel);
  if (!box) return;
  const dot  = box.querySelector('.status-dot');
  const text = box.querySelector('.status-text');
  if (dot)  dot.className  = `status-dot status-${kind}`;
  if (text) text.innerHTML = html;
}

function setRunning(running) {
  const btn = $('#genBtn'); if (!btn) return;
  btn.disabled = running;
  const spin = btn.querySelector('.btn-spinner');
  const lbl  = btn.querySelector('.btn-label');
  if (spin) spin.hidden = !running;
  if (lbl)  lbl.textContent = running ? '생성 중…' : '⚡ Generate';
}

/* ── Pipeline animation ───────────────────────────────────── */
function animatePipeline() {
  resetPipeline();
  const stages = ['corpus', 'encoding', 'incubation', 'emergence', 'filtering'];
  let i = 0;
  const tick = () => {
    if (i > 0) {
      const prev = document.querySelector(`.stage[data-stage="${stages[i-1]}"]`);
      if (prev) { prev.classList.remove('active'); prev.classList.add('done'); }
    }
    if (i < stages.length) {
      const cur = document.querySelector(`.stage[data-stage="${stages[i]}"]`);
      if (cur) cur.classList.add('active');
      i++;
      PIPELINE_TIMER = setTimeout(tick, 1200);
    }
  };
  tick();
}

function completePipeline() {
  if (PIPELINE_TIMER) { clearTimeout(PIPELINE_TIMER); PIPELINE_TIMER = null; }
  $$('.stage').forEach(s => { s.classList.remove('active'); s.classList.add('done'); });
}

function resetPipeline() {
  if (PIPELINE_TIMER) { clearTimeout(PIPELINE_TIMER); PIPELINE_TIMER = null; }
  $$('.stage').forEach(s => s.classList.remove('active', 'done'));
}

/* ── Render results ───────────────────────────────────────── */
function renderResults(data) {
  LATEST_RESULTS = data;
  // Reset media state for a fresh run
  Object.keys(MEDIA_STATE).forEach(k => { delete MEDIA_STATE[k]; });

  const bar = $('#summaryBar'); if (bar) bar.hidden = false;
  if ($('#sumCount'))   $('#sumCount').textContent   = data.summary.count;
  if ($('#sumAvg'))     $('#sumAvg').textContent     = (data.summary.avg_final || 0).toFixed(3);
  if ($('#sumTop'))     $('#sumTop').textContent     = (data.summary.top_final || 0).toFixed(3);
  if ($('#sumBackend')) $('#sumBackend').textContent =
    data.summary.backend +
    (data.summary.model ? ' · ' + data.summary.model.split('/').pop() : '');

  CHARTS.forEach(c => { try { c.destroy(); } catch(_){} });
  CHARTS = [];
  const box = $('#seedsBox'); if (!box) return;
  box.innerHTML = '';
  data.seeds.forEach((s, idx) => {
    box.appendChild(renderSeedCard(s, idx + 1));
  });

  // Kick off the fal.ai auto-chain for the top 3 seeds' first beat
  if (HAS_FAL) {
    autoMediaChain(data.seeds);
  } else {
    showFalMissingBanner();
  }
}

function showFalMissingBanner() {
  // soft notice at top of seeds list
  const box = $('#seedsBox'); if (!box) return;
  const notice = document.createElement('div');
  notice.className = 'err';
  notice.style.marginBottom = '12px';
  notice.textContent = '⚠️ FAL_KEY 미설정 — 이미지/비디오 생성이 비활성됩니다 (Settings → Secrets → FAL_KEY).';
  box.prepend(notice);
}

function renderSeedCard(s, rank) {
  const seed  = s.seed;
  const score = s.score;
  const final = score.final;
  const color = final >= 0.5 ? '#10b981' : final >= 0.3 ? '#f59e0b' : '#ef4444';
  const R = 34, CIRC = 2 * Math.PI * R;
  const offset = CIRC * (1 - Math.max(0, Math.min(1, final)));

  const card = document.createElement('div');
  card.className = 'seed-card';
  card.innerHTML = `
    <div class="seed-head">
      <div class="seed-rank-block">
        <span class="seed-rank-label">Rank</span>
        <div class="seed-rank">#${rank}</div>
      </div>
      <div class="seed-info">
        <div class="seed-id">${escapeHtml(seed.seed_id)}</div>
        <div class="seed-rules">
          ${seed.rules_applied.map(r => `<span class="rule-pill">${escapeHtml(r)}</span>`).join('')}
        </div>
      </div>
      <div class="final-gauge" title="final score">
        <svg viewBox="0 0 80 80">
          <circle class="final-gauge-track" cx="40" cy="40" r="${R}"/>
          <circle class="final-gauge-fill"  cx="40" cy="40" r="${R}"
                  stroke="${color}"
                  stroke-dasharray="${CIRC}"
                  stroke-dashoffset="${offset}"/>
        </svg>
        <div class="final-gauge-text">
          <div>
            <div class="final-gauge-value">${final.toFixed(2)}</div>
            <div class="final-gauge-label">final</div>
          </div>
        </div>
      </div>
    </div>

    ${seed.scene_summary ? `
      <div class="scene-summary">
        <span class="scene-summary-badge">📜 한 줄 요약</span>
        <span class="scene-summary-text">${escapeHtml(seed.scene_summary)}</span>
      </div>` : ''}

    ${seed.wow_anchor ? `<div class="seed-anchor">${escapeHtml(seed.wow_anchor)}</div>` : ''}

    ${renderTournament(seed.tournament)}

    ${renderConstraints(seed.creative_constraints)}

    <div class="seed-section-title">Concept</div>
    <div class="seed-concept">${escapeHtml(seed.concept)}</div>

    <div class="seed-section-title">Pixar Story Spine · ${seed.duration}s · ${seed.beats.length} beats</div>
    <div class="timeline">
      <div class="timeline-bar">${renderBeatBar(seed.beats, seed.duration)}</div>
      <div class="timeline-scale">${renderTicks(seed.duration)}</div>
    </div>

    <div class="seed-section-title">Beats · 이미지/비디오</div>
    <div class="beats-detail">
      ${seed.beats.map((b, bi) => `
        <div class="beat-row">
          <div class="beat-row-time">${b.time_range[0]}–${b.time_range[1]}s</div>
          <div class="beat-row-name">${escapeHtml(b.beat)}</div>
          <div class="beat-row-content">${escapeHtml(b.content || '—')}</div>
          <div class="beat-media" data-media="${rank - 1}-${bi}"></div>
        </div>
      `).join('')}
    </div>

    <div data-stitch-host="${rank - 1}"></div>

    <div class="aether-provenance" title="AETHER 5-생성자가 내부에서 서로를 상생·상극으로 조율하여 이 하나의 장면을 합성했습니다.">
      ⚙️ AETHER 5-생성자 메타인지: 木(씨앗) → 火(증폭) → 土(지반) → 金(편집) → 水(통합)
    </div>

    ${renderAetherCritique(seed.aether_critique)}

    ${renderRawDetails(seed)}

    <div class="scores-section">
      <div class="radar-wrap"><canvas></canvas></div>
      <div class="scores-table">
        ${scoreItem('Novelty',      score.novelty)}
        ${scoreItem('Utility',      score.utility)}
        ${scoreItem('Affect',       score.affect)}
        ${scoreItem('Humor/Pathos', score.humor_or_pathos)}
        ${scoreItem('Surprise',     score.surprise)}
        ${scoreItem('Risk',         score.risk, { risk: true })}
        ${scoreItem('Gating',       (score.gating_passed || 0) + '/5', { raw: true })}
        ${scoreItem('Final',        score.final, { bold: true })}
      </div>
    </div>
  `;

  const canvas = $('canvas', card);
  const chart = new Chart(canvas.getContext('2d'), {
    type: 'radar',
    data: {
      labels: ['Novelty', 'Utility', 'Affect', 'Humor/Pathos', 'Surprise'],
      datasets: [{
        data: [
          score.novelty, score.utility, score.affect,
          score.humor_or_pathos, score.surprise,
        ],
        backgroundColor: 'rgba(79, 70, 229, 0.18)',
        borderColor: '#4f46e5',
        borderWidth: 2,
        pointBackgroundColor: '#4f46e5',
        pointBorderColor: '#ffffff',
        pointRadius: 3,
      }],
    },
    options: {
      responsive: true, maintainAspectRatio: false,
      plugins: { legend: { display: false } },
      scales: {
        r: {
          suggestedMin: 0, suggestedMax: 1,
          ticks:       { display: false, stepSize: 0.25 },
          grid:        { color: '#e6e9f0' },
          angleLines:  { color: '#e6e9f0' },
          pointLabels: { font: { size: 10, weight: '600' }, color: '#475569' },
        },
      },
    },
  });
  CHARTS.push(chart);

  // Initialize media slots AFTER DOM insertion — queued as a microtask so
  // the card is already in the tree when we query data-media attributes.
  queueMicrotask(() => {
    seed.beats.forEach((_, bi) => renderMediaSlot(rank - 1, bi));
    renderStitchSection(rank - 1);
  });

  return card;
}

function renderTournament(t) {
  if (!t || typeof t !== 'object') return '';
  const inv = (t.structural_invention || '').trim();
  const why = (t.why_winner || '').trim();
  const ru  = (t.runners_up || '').trim();
  if (!inv && !why) return '';
  return `
    <div class="tournament">
      <div class="tournament-head">
        <span class="tournament-badge">🏆 토너먼트 우승</span>
        <span class="tournament-label">LLM 판사가 ${escapeHtml(t.winner_index !== undefined ? '#' + (Number(t.winner_index) + 1) : '')} 후보를 구조적 창발 1위로 선정</span>
      </div>
      ${inv ? `
        <div class="tournament-row">
          <span class="tournament-key">구조적 발명</span>
          <span class="tournament-val tournament-val-invention">${escapeHtml(inv)}</span>
        </div>` : ''}
      ${why ? `
        <div class="tournament-row">
          <span class="tournament-key">결정적 이유</span>
          <span class="tournament-val">${escapeHtml(why)}</span>
        </div>` : ''}
      ${ru ? `
        <div class="tournament-row">
          <span class="tournament-key">차점자 약점</span>
          <span class="tournament-val tournament-val-muted">${escapeHtml(ru)}</span>
        </div>` : ''}
    </div>
  `;
}

function renderAetherCritique(c) {
  if (!c || typeof c !== 'object') return '';
  const verdict = (c.verdict || 'PASS').toUpperCase();
  const isRevise = verdict === 'REVISE';
  const verdictBadge = isRevise
    ? '<span class="critique-verdict critique-verdict-revise">REVISE → 재집필 적용됨</span>'
    : '<span class="critique-verdict critique-verdict-pass">PASS → 추가 수정 없음</span>';
  const rows = [
    ['🌳 木 직관',       c.wood,  '木 (Wood) — KEY VISUAL이 1년 뒤에도 기억나는가? 클리셰는?'],
    ['🔥 火 감정',       c.fire,  '火 (Fire) — 첫 3초가 손을 멈추게 하는가? 추상어로 도망친 곳은?'],
    ['🪨 土 논리·필연',  c.earth, '土 (Earth) — 다른 브랜드로 바꿔도 성립하는가?'],
    ['⚔️ 金 비판·절단',  c.metal, '金 (Metal) — 가장 약한 BEAT + 즉시 강해지는 대안.'],
    ['🌊 水 통찰',       c.water, '水 (Water) — 보지 못한 진실 + 톱 CF에 닿지 못한 결.'],
  ].filter(([, v]) => v && v.trim());
  if (!rows.length && !c.revision_brief) return '';
  const briefBlock = c.revision_brief && c.revision_brief.trim()
    ? `<div class="critique-brief"><span class="critique-brief-label">재집필 지시</span>
       <span class="critique-brief-text">${escapeHtml(c.revision_brief)}</span></div>`
    : '';
  return `
    <details class="critique" ${isRevise ? 'open' : ''}>
      <summary class="critique-summary">
        🧠 AETHER 메타인지 비평 ${verdictBadge}
      </summary>
      <div class="critique-body">
        <div class="critique-grid">
          ${rows.map(([k, v, tip]) => `
            <div class="critique-row" title="${escapeHtml(tip)}">
              <span class="critique-key">${k}</span>
              <span class="critique-val">${escapeHtml(v)}</span>
            </div>`).join('')}
        </div>
        ${briefBlock}
      </div>
    </details>
  `;
}

function renderConstraints(c) {
  if (!c) return '';
  const rows = [
    ['📦 오브제',     c.object],
    ['🎥 카메라',     c.shot],
    ['🔀 공감각',     c.synesthesia],
    ['🎬 장르 전환',  c.genre_twist],
    ['⏱ 시간 구조',  c.time],
    ['🔊 의성어',     c.onomatopoeia],
  ].filter(([, v]) => v);
  if (!rows.length) return '';
  return `
    <div class="constraints">
      <div class="constraints-head">창발 강제 조건 <small>· Kimi-K2P6에 하드 주입된 구체 제약</small></div>
      <div class="constraints-grid">
        ${rows.map(([k, v]) => `
          <div class="constraint-chip">
            <span class="constraint-key">${k}</span>
            <span class="constraint-val">${escapeHtml(v)}</span>
          </div>`).join('')}
      </div>
    </div>
  `;
}

/* ── Media (fal.ai images + Bytedance Seedance 2.0 video) ──────────────── */

const STITCH_STATE = {};         // legacy; not used by auto chain anymore
const FINAL_VIDEO_STATE = {};    // FINAL_VIDEO_STATE[seedIdx] = {status, video_url, target_seconds, message}

/** Auto-pipeline (top seed only):
 *   Phase 1 — generate images for ALL beats with sliding-window ref chain
 *   Phase 2 — ONE single i2v call (Seedance 2.0) using the first chained
 *             image + a combined multi-scene prompt → one full-spot video
 */
async function autoMediaChain(seeds) {
  if (!seeds || !seeds.length) return;
  const sIdx = 0;
  const beats = seeds[sIdx].seed.beats || [];
  if (!beats.length) return;

  // Phase 1 — image chain (same as before)
  for (let i = 0; i < beats.length; i++) {
    const ok = await _genImageForBeat(sIdx, i, /*useChain*/ true);
    if (!ok) break;
  }

  // Phase 2 — single full-spot Seedance video
  await generateFinalVideo(sIdx);
  renderStitchSection(sIdx);   // backward-compat: clears any old stitch UI
}

/** Build a single multi-scene prompt that walks Seedance through every beat. */
function buildCombinedScenePrompt(beats) {
  const total = beats[beats.length - 1]?.time_range?.[1] || 15;
  const lines = [
    `다음은 ${total}초 길이의 시네마틱 광고 영상이다. ${beats.length}개의 씬이 부드럽게 이어진다.`,
    "각 씬을 명시된 타임코드 동안 연출하고, 씬 사이에 자연스러운 컷·매치 컷·디졸브를 사용한다.",
    "",
  ];
  beats.forEach((b, i) => {
    lines.push(`Scene ${i + 1} (${b.time_range[0]}-${b.time_range[1]}초)`);
    if (b.content) lines.push(b.content);
    lines.push("");
  });
  lines.push("전체 영상은 영화적 연속성을 유지하며, 첫 컷의 인물·환경이 자연스럽게 발전한다. 자막·텍스트·로고 일체 없음.");
  return lines.join("\n");
}

function _isContentPolicyError(msg) {
  const m = String(msg || '').toLowerCase();
  return m.includes('content_policy_violation')
      || m.includes('content policy')
      || m.includes('likenesses of real people')
      || m.includes('private information');
}

/** Generate a single full-spot video (Seedance 2.0).
 *  Anchor = first chained image. If Seedance rejects on content policy,
 *  automatically retry with the next image in the chain. */
async function generateFinalVideo(sIdx, anchorBeatIdx = 0) {
  const seed = LATEST_RESULTS?.seeds?.[sIdx]?.seed;
  if (!seed) return;
  const beats = seed.beats || [];
  if (!beats.length) return;

  // Build candidate list (any beat with an image) starting from anchorBeatIdx
  const allCandidates = [];
  for (let i = 0; i < beats.length; i++) {
    const u = MEDIA_STATE[sIdx]?.[i]?.image_url;
    if (u) allCandidates.push({ beatIdx: i, url: u });
  }
  if (!allCandidates.length) {
    FINAL_VIDEO_STATE[sIdx] = {
      status: 'error',
      message: '이미지가 아직 생성되지 않아 비디오를 시작할 수 없습니다.',
    };
    renderFinalVideoSection(sIdx);
    return;
  }
  // Reorder so anchorBeatIdx comes first, then the rest in beat order
  const candidates = [
    ...allCandidates.filter(c => c.beatIdx === anchorBeatIdx),
    ...allCandidates.filter(c => c.beatIdx !== anchorBeatIdx),
  ];

  const totalSec = beats[beats.length - 1].time_range[1];
  const combinedScene = buildCombinedScenePrompt(beats);

  let lastErr = '';
  let policyRejections = 0;
  for (let attempt = 0; attempt < candidates.length; attempt++) {
    const cand = candidates[attempt];
    FINAL_VIDEO_STATE[sIdx] = {
      status: 'loading',
      target_seconds: totalSec,
      anchor_beat: cand.beatIdx,
      message: attempt === 0
        ? `🎬 Seedance 2.0이 ${totalSec}초 영상 생성 중… (앵커: 비트 ${cand.beatIdx + 1}, 3~6분)`
        : `⚠️ 정책 거부 ${policyRejections}회 — 비트 ${cand.beatIdx + 1} 이미지로 재시도 중…`,
    };
    renderFinalVideoSection(sIdx);

    try {
      const r = await fetch('/api/media/video', {
        method: 'POST',
        headers: {'Content-Type': 'application/json'},
        body: JSON.stringify({
          scene: combinedScene,
          image_url: cand.url,
          duration_seconds: totalSec,
        }),
      });
      const data = await r.json();
      if (!r.ok) throw new Error(data.detail || `HTTP ${r.status}`);
      FINAL_VIDEO_STATE[sIdx] = {
        status: 'ready',
        video_url: data.video_url,
        target_seconds: totalSec,
        anchor_beat: cand.beatIdx,
        policy_retries: policyRejections,
      };
      renderFinalVideoSection(sIdx);
      return;
    } catch (e) {
      const msg = e.message || String(e);
      lastErr = msg;
      if (_isContentPolicyError(msg)) {
        policyRejections += 1;
        continue;   // try next candidate
      }
      // non-policy error: stop, show
      FINAL_VIDEO_STATE[sIdx] = {
        status: 'error',
        target_seconds: totalSec,
        message: `비디오 생성 실패: ${msg}`,
      };
      renderFinalVideoSection(sIdx);
      return;
    }
  }
  // All candidates rejected by policy
  FINAL_VIDEO_STATE[sIdx] = {
    status: 'error',
    target_seconds: totalSec,
    message: `Seedance가 모든 이미지를 정책으로 거부 (${policyRejections}회). `
           + `이미지를 재생성한 뒤 (인물 정면 포트레이트 회피) 다시 시도하세요. ${lastErr.slice(0, 200)}`,
  };
  renderFinalVideoSection(sIdx);
}

/** Render the single-final-video section at the bottom of the seed card. */
function renderFinalVideoSection(sIdx) {
  const host = document.querySelector(`[data-stitch-host="${sIdx}"]`);
  if (!host) return;
  const seed = LATEST_RESULTS?.seeds?.[sIdx]?.seed;
  if (!seed) { host.innerHTML = ''; return; }
  const totalSec = seed.beats[seed.beats.length - 1]?.time_range?.[1] || 15;
  const st = FINAL_VIDEO_STATE[sIdx] || {};
  const beats = seed.beats || [];
  const imagesReady = beats.filter((_, i) => MEDIA_STATE[sIdx]?.[i]?.image_url).length;

  const html = [];
  html.push(`<div class="seed-section-title">🎬 최종 ${totalSec}초 광고 영상 (Bytedance Seedance 2.0)</div>`);
  html.push(`<div class="final-stitch">`);

  if (st.status === 'loading') {
    html.push(`<div class="media-status media-loading">${escapeHtml(st.message)}</div>`);
  } else if (st.status === 'error') {
    html.push(`<div class="media-status media-error-msg">${escapeHtml(st.message)}</div>`);
  }

  if (st.video_url) {
    const anchorIdx = (typeof st.anchor_beat === 'number') ? st.anchor_beat + 1 : 1;
    const retryNote = st.policy_retries
      ? ` · 정책 거부 ${st.policy_retries}회 후 재시도 성공`
      : '';
    html.push(`
      <div class="media-thumb stitch-thumb">
        <video src="${escapeAttr(st.video_url)}" controls playsinline preload="metadata"></video>
      </div>
      <div class="stitch-progress">
        ${totalSec}초 영상 · ${beats.length}개 씬 통합 i2v · 앵커 이미지: 비트 ${anchorIdx}${retryNote}
      </div>
      <div class="stitch-actions">
        <a class="btn-stitch-download"
           href="/api/media/download?url=${encodeURIComponent(st.video_url)}&filename=aether_final_seed${sIdx}_${totalSec}s.mp4"
           title="최종 영상 다운로드">↓ ${totalSec}초 광고 다운로드</a>
        <button type="button" class="btn-stitch" data-final-seed="${sIdx}">🔄 영상 재생성</button>
      </div>
    `);
  } else if (st.status !== 'loading') {
    const enough = imagesReady >= 1;
    const disabled = !enough ? 'disabled' : '';
    // If a previous run errored on policy, surface a "Try with another anchor" hint
    const anchorButtons = (st.status === 'error' && imagesReady > 1)
      ? beats.map((_, i) => MEDIA_STATE[sIdx]?.[i]?.image_url
            ? `<button type="button" class="btn-media" data-final-seed="${sIdx}" data-anchor-beat="${i}">🎯 비트 ${i + 1} 이미지로 재시도</button>`
            : ''
          ).join('')
      : '';
    html.push(`
      <div class="stitch-progress">
        이미지 ${imagesReady}/${beats.length} 준비
        ${enough ? `· ${totalSec}초 단일 영상 생성 가능` : '— 첫 비트 이미지부터 필요'}
      </div>
      <button type="button" class="btn-stitch" data-final-seed="${sIdx}" ${disabled}>
        🎬 ${totalSec}초 광고 영상 생성 (Seedance 2.0, 한 번 호출)
      </button>
      ${anchorButtons ? `<div class="media-controls" style="flex-direction:row;flex-wrap:wrap;">${anchorButtons}</div>` : ''}
    `);
  }

  html.push(`</div>`);
  host.innerHTML = html.join('');
}

/** Backward-compat: keep the old name pointing at the new section. */
function renderStitchSection(sIdx) {
  renderFinalVideoSection(sIdx);
}

/** Generate image for one beat. If useChain, attach last 3 prior images as refs. */
async function _genImageForBeat(sIdx, bIdx, useChain) {
  const beat = LATEST_RESULTS?.seeds?.[sIdx]?.seed?.beats?.[bIdx];
  if (!beat?.content) return false;
  const total = LATEST_RESULTS.seeds[sIdx].seed.beats.length;

  const refs = [];
  if (useChain) {
    for (let k = Math.max(0, bIdx - 3); k < bIdx; k++) {
      const u = MEDIA_STATE[sIdx]?.[k]?.image_url;
      if (u) refs.push(u);
    }
  }

  _setMediaState(sIdx, bIdx, {
    status: 'loading',
    kind: 'image',
    message: refs.length
      ? `🖼 이미지 ${bIdx + 1}/${total} (참조 ${refs.length})…`
      : `🖼 이미지 ${bIdx + 1}/${total} 생성 중…`,
  });
  try {
    const body = { scene: beat.content };
    if (refs.length) body.ref_image_urls = refs;
    const r = await fetch('/api/media/image', {
      method: 'POST',
      headers: {'Content-Type': 'application/json'},
      body: JSON.stringify(body),
    });
    const data = await r.json();
    if (!r.ok) throw new Error(data.detail || `HTTP ${r.status}`);
    _setMediaState(sIdx, bIdx, { image_url: data.image_url, status: 'ready' });
    return true;
  } catch (e) {
    _setMediaState(sIdx, bIdx, {
      status: 'error', kind: 'image',
      message: `이미지 실패: ${e.message || e}`,
    });
    return false;
  }
}

async function _genVideoForBeat(sIdx, bIdx) {
  const beat = LATEST_RESULTS?.seeds?.[sIdx]?.seed?.beats?.[bIdx];
  if (!beat?.content) return false;
  const imgUrl = MEDIA_STATE[sIdx]?.[bIdx]?.image_url;
  if (!imgUrl) return false;
  const total = LATEST_RESULTS.seeds[sIdx].seed.beats.length;

  _setMediaState(sIdx, bIdx, {
    status: 'loading', kind: 'video',
    message: `🎬 비디오 ${bIdx + 1}/${total} 생성 중… (60-180초)`,
  });
  try {
    const r = await fetch('/api/media/video', {
      method: 'POST',
      headers: {'Content-Type': 'application/json'},
      body: JSON.stringify({scene: beat.content, image_url: imgUrl}),
    });
    const data = await r.json();
    if (!r.ok) throw new Error(data.detail || `HTTP ${r.status}`);
    _setMediaState(sIdx, bIdx, { video_url: data.video_url, status: 'ready' });
    return true;
  } catch (e) {
    _setMediaState(sIdx, bIdx, {
      status: 'error', kind: 'video',
      message: `비디오 실패: ${e.message || e}`,
    });
    return false;
  }
}

/** Manual handlers — buttons call these. */
async function manualGenerateImage(sIdx, bIdx) {
  await _genImageForBeat(sIdx, bIdx, /*useChain*/ true);
  // re-render stitch in case state changed
  renderStitchSection(sIdx);
}

// manualGenerateVideo removed — single full-spot Seedance video replaces per-beat i2v.

/** Manual: text-to-image for any beat (no refs). */
async function manualGenerateImage(sIdx, bIdx) {
  const beat = LATEST_RESULTS?.seeds?.[sIdx]?.seed?.beats?.[bIdx];
  if (!beat || !beat.content) return;
  _setMediaState(sIdx, bIdx, {
    status: 'loading',
    kind: 'image',
    message: '🖼 이미지 생성 중…',
  });
  try {
    const r = await fetch('/api/media/image', {
      method: 'POST',
      headers: {'Content-Type': 'application/json'},
      body: JSON.stringify({scene: beat.content}),
    });
    const data = await r.json();
    if (!r.ok) throw new Error(data.detail || `HTTP ${r.status}`);
    _setMediaState(sIdx, bIdx, { image_url: data.image_url, status: 'ready' });
  } catch (e) {
    _setMediaState(sIdx, bIdx, {
      status: 'error',
      kind: 'image',
      message: `이미지 실패: ${e.message || e}`,
    });
  }
}

/* manualGenerateVideo: removed. Single Seedance 2.0 call replaces it. */

/** Merge partial state, then re-render the slot. */
function _setMediaState(sIdx, bIdx, patch) {
  MEDIA_STATE[sIdx] = MEDIA_STATE[sIdx] || {};
  MEDIA_STATE[sIdx][bIdx] = Object.assign(
    {},
    MEDIA_STATE[sIdx][bIdx] || {},
    patch,
  );
  renderMediaSlot(sIdx, bIdx);
}

function renderMediaSlot(sIdx, bIdx) {
  const slot = document.querySelector(`[data-media="${sIdx}-${bIdx}"]`);
  if (!slot) return;
  const st = (MEDIA_STATE[sIdx] || {})[bIdx] || {};
  const isAuto = bIdx === 0 && sIdx < 3;   // first beat of top 3 seeds is auto
  slot.innerHTML = mediaSlotHtml(sIdx, bIdx, st, isAuto);
}

function mediaSlotHtml(sIdx, bIdx, st, _isAuto) {
  const parts = [];
  // Status (loading / error) — image only; per-beat video is gone.
  if (st.status === 'loading' && st.message) {
    parts.push(`<div class="media-status media-loading">${escapeHtml(st.message)}</div>`);
  } else if (st.status === 'error' && st.message) {
    parts.push(`<div class="media-status media-error-msg">${escapeHtml(st.message)}</div>`);
  }
  const fname = (kind) => `aether_${sIdx}_${String(bIdx).padStart(2,'0')}.${kind}`;

  // Image preview
  if (st.image_url) {
    parts.push(`
      <div class="media-thumb">
        <img src="${escapeAttr(st.image_url)}" alt="scene ${bIdx + 1}" loading="lazy" />
        <a class="media-download"
           href="/api/media/download?url=${encodeURIComponent(st.image_url)}&filename=${encodeURIComponent(fname('jpg'))}"
           title="이미지 다운로드">↓</a>
      </div>
    `);
  }
  // (Per-beat video preview removed — single full-spot video lives at card bottom.)

  // Image-only controls — single i2v video is generated once for the whole spot.
  if (HAS_FAL) {
    const imgDisabled = st.status === 'loading' ? 'disabled' : '';
    const imgLabel = st.image_url ? '🔄 이미지 재생성' : '🖼 이미지 생성';
    parts.push(`
      <div class="media-controls">
        <button type="button" class="btn-media" data-media-btn="image"
                data-seed="${sIdx}" data-beat="${bIdx}" ${imgDisabled}>${imgLabel}</button>
      </div>
    `);
  }
  return parts.join('');
}

/* (Legacy renderStitchSection / stitchAllVideos removed — replaced by
 *  renderFinalVideoSection + generateFinalVideo defined earlier in this file.
 *  The forwarder near the top still exposes `renderStitchSection` for any
 *  call sites that haven't migrated yet.)
 */

function escapeAttr(s) {
  return String(s || '').replace(/"/g, '&quot;').replace(/</g, '&lt;');
}

/* Delegate clicks on per-beat image buttons + final-video regen + anchor retry. */
document.addEventListener('click', (e) => {
  // Final-video regen / try-another-anchor (.btn-media or .btn-stitch with data-final-seed)
  const finalEl = e.target.closest('[data-final-seed]');
  if (finalEl && !finalEl.disabled) {
    const sIdx = parseInt(finalEl.dataset.finalSeed ?? finalEl.dataset.stitchSeed, 10);
    const anchor = finalEl.dataset.anchorBeat;
    if (!Number.isNaN(sIdx)) {
      generateFinalVideo(sIdx, anchor !== undefined ? parseInt(anchor, 10) : 0);
    }
    return;
  }
  const finalBtn = e.target.closest('.btn-stitch');
  if (finalBtn && !finalBtn.disabled) {
    const sIdx = parseInt(finalBtn.dataset.stitchSeed, 10);
    if (!Number.isNaN(sIdx)) generateFinalVideo(sIdx);
    return;
  }
  const btn = e.target.closest('.btn-media');
  if (!btn) return;
  const sIdx = parseInt(btn.dataset.seed, 10);
  const bIdx = parseInt(btn.dataset.beat, 10);
  if (btn.dataset.mediaBtn === 'image') {
    manualGenerateImage(sIdx, bIdx);
  }
});


function renderRawDetails(seed) {
  const parts = [];
  if (seed.raw_collision) {
    parts.push(`
      <details class="raw-details">
        <summary>📝 모델 원본 출력 · Concept (참고자료)</summary>
        <pre class="raw-body">${escapeHtml(seed.raw_collision)}</pre>
      </details>
    `);
  }
  if (seed.raw_spine) {
    parts.push(`
      <details class="raw-details">
        <summary>📝 모델 원본 출력 · Pixar Spine (참고자료)</summary>
        <pre class="raw-body">${escapeHtml(seed.raw_spine)}</pre>
      </details>
    `);
  }
  return parts.join('');
}

function renderBeatBar(beats, duration) {
  return beats.map((b, i) => {
    const pct = ((b.time_range[1] - b.time_range[0]) / duration) * 100;
    const short = (b.beat || '').split('_')[0] || b.beat;
    return `
      <div class="beat-seg beat-color-${Math.min(i, 5)}" style="width: ${pct}%;"
           title="${escapeHtml(b.beat)} · ${b.time_range[0]}-${b.time_range[1]}s">
        <div class="beat-seg-name">${escapeHtml(short)}</div>
        <div class="beat-seg-time">${b.time_range[0]}-${b.time_range[1]}s</div>
      </div>
    `;
  }).join('');
}

function renderTicks(duration) {
  const ticks = duration === 15 ? [0, 3, 6, 9, 12, 15] : [0, 5, 10, 15, 20, 25, 30];
  return ticks.map(t => {
    const left = (t / duration) * 100;
    return `<span class="timeline-tick" style="left: ${left}%;">${t}s</span>`;
  }).join('');
}

function scoreItem(label, val, opts = {}) {
  const v = opts.raw ? val : (typeof val === 'number' ? val.toFixed(3) : val);
  const style = [];
  if (opts.risk && Number(val) > 0) style.push('color: var(--danger);');
  if (opts.bold)                    style.push('color: var(--primary); font-size: 15px;');
  return `
    <div class="score-item">
      <span class="score-item-label">${label}</span>
      <span class="score-item-value" style="${style.join(' ')}">${v}</span>
    </div>
  `;
}

function escapeHtml(s) {
  if (s == null) return '';
  return String(s).replace(/[&<>"']/g, ch => ({
    '&':'&amp;','<':'&lt;','>':'&gt;','"':'&quot;',"'":'&#39;',
  }[ch]));
}