09여러 계산을 한 패널에 모은 댓글 목록 히어로 장면

<main class="stage">
<div class="hero is-demo" id="heroRoot">
  <ul class="hero__list" role="list" id="heroList">
    <li class="hero__cmt" data-depth="0" data-id="h1">
      <span class="hero__avatar" aria-hidden="true"></span>
      <div class="hero__body">
        <p class="hero__meta"><strong class="hero__name">노을빛선장</strong></p>
        <p class="hero__text">세 가지 움직임이 한 패널에 섞였어요.</p>
        <button type="button" class="hero__likeBtn" id="heroLike1" aria-pressed="false" aria-label="좋아요">
          <svg class="hero__heart" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M232 102c0 66-104 122-104 122S24 168 24 102a54 54 0 0 1 54-54c22.59 0 41.94 12.31 50 32c8.06-19.69 27.41-32 50-32a54 54 0 0 1 54 54" opacity=".2"/><path d="M178 40c-20.65 0-38.73 8.88-50 23.89C116.73 48.88 98.65 40 78 40a62.07 62.07 0 0 0-62 62c0 70 103.79 126.66 108.21 129a8 8 0 0 0 7.58 0C136.21 228.66 240 172 240 102a62.07 62.07 0 0 0-62-62m-50 174.8c-18.26-10.64-96-59.11-96-112.8a46.06 46.06 0 0 1 46-46c19.45 0 35.78 10.36 42.6 27a8 8 0 0 0 14.8 0c6.82-16.67 23.15-27 42.6-27a46.06 46.06 0 0 1 46 46c0 53.61-77.76 102.15-96 112.8"/></g></svg>
          <span class="hero__count" id="heroCount1">187</span>
        </button>
        <button type="button" class="hero__delBtn" id="heroDel1" aria-label="댓글 삭제">
          <svg class="hero__icon" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M200 56v152a8 8 0 0 1-8 8H64a8 8 0 0 1-8-8V56Z" opacity=".2"/><path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16M96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0m48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0"/></g></svg>
        </button>
      </div>
    </li>
    <li class="hero__cmt" data-depth="1" data-id="h2">
      <span class="hero__guide" aria-hidden="true"></span>
      <span class="hero__avatar hero__avatar--sm" aria-hidden="true"></span>
      <div class="hero__body">
        <p class="hero__meta"><strong class="hero__name">무지개다리</strong></p>
        <p class="hero__text">답글 들여쓰기가 깊이에 비례해서 밀리네요.</p>
      </div>
    </li>
    <li class="hero__cmt" data-depth="2" data-id="h3">
      <span class="hero__guide" aria-hidden="true"></span>
      <span class="hero__avatar hero__avatar--sm" aria-hidden="true"></span>
      <div class="hero__body">
        <p class="hero__meta"><strong class="hero__name">이슬털기</strong></p>
        <p class="hero__text">대댓글 안내선은 위에서 아래로 그려지고.</p>
      </div>
    </li>
    <li class="hero__cmt" data-depth="0" data-id="h4">
      <span class="hero__avatar" aria-hidden="true"></span>
      <div class="hero__body">
        <p class="hero__meta"><strong class="hero__name">바위틈새</strong></p>
        <p class="hero__text">이 댓글을 삭제하면 아래가 스프링으로 올라와요.</p>
        <button type="button" class="hero__likeBtn" id="heroLike4" aria-pressed="false" aria-label="좋아요">
          <svg class="hero__heart" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M232 102c0 66-104 122-104 122S24 168 24 102a54 54 0 0 1 54-54c22.59 0 41.94 12.31 50 32c8.06-19.69 27.41-32 50-32a54 54 0 0 1 54 54" opacity=".2"/><path d="M178 40c-20.65 0-38.73 8.88-50 23.89C116.73 48.88 98.65 40 78 40a62.07 62.07 0 0 0-62 62c0 70 103.79 126.66 108.21 129a8 8 0 0 0 7.58 0C136.21 228.66 240 172 240 102a62.07 62.07 0 0 0-62-62m-50 174.8c-18.26-10.64-96-59.11-96-112.8a46.06 46.06 0 0 1 46-46c19.45 0 35.78 10.36 42.6 27a8 8 0 0 0 14.8 0c6.82-16.67 23.15-27 42.6-27a46.06 46.06 0 0 1 46 46c0 53.61-77.76 102.15-96 112.8"/></g></svg>
          <span class="hero__count" id="heroCount4">94</span>
        </button>
        <button type="button" class="hero__delBtn" id="heroDel4" aria-label="댓글 삭제">
          <svg class="hero__icon" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M200 56v152a8 8 0 0 1-8 8H64a8 8 0 0 1-8-8V56Z" opacity=".2"/><path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16M96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0m48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0"/></g></svg>
        </button>
      </div>
    </li>
  </ul>
  <button type="button" class="hero__resetBtn" id="heroReset">되돌리기</button>
  <p class="hero__sr" id="heroStatus" aria-live="polite"></p>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);

.hero {
  position: relative;
  width: min(92vw, calc(160vh - 12.8vw));
  aspect-ratio: 480 / 300;
  margin: 0 auto;
  border-radius: $r-card;
  overflow: hidden;
  box-shadow: $shadow-raised;
  background: $tick-panel;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  box-sizing: border-box;
  padding: $sp-4;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}

.hero__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
  flex: 1;
}

.hero__cmt {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: $sp-2;
  padding: $sp-2 $sp-3;
  background: rgba(255, 255, 255, .05);
  border-radius: $r-sm;
  will-change: transform, height;
}

.hero__guide {
  position: absolute;
  left: -12px;
  top: 0;
  width: 2px;
  height: 100%;
  background: $subject-blue-light;
  opacity: .55;
  border-radius: $r-pill;
  transform: scaleY(0);
  transform-origin: top;
}

.hero__avatar {
  flex: none;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: linear-gradient(160deg, $subject-mint, $subject-blue-light);

  &--sm {
    width: 20px;
    height: 20px;
    background: linear-gradient(160deg, $subject-sky, $subject-lilac);
  }
}

.hero__body { min-width: 0; flex: 1; }
.hero__meta { margin: 0 0 4px; }
.hero__name { color: #fff; font-size: 12px; font-weight: 700; }
.hero__text { margin: 0 0 $sp-1; color: rgba(255, 255, 255, .86); font-size: 12px; line-height: 1.5; }

.hero__likeBtn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 0;
  background: rgba(255, 255, 255, .06);
  color: rgba(255, 255, 255, .7);
  padding: 4px $sp-2;
  border-radius: $r-pill;
  font-size: 11px;
  font-weight: 700;
  cursor: pointer;
  margin-right: $sp-1;

  &:focus-visible { outline: 2px solid $subject-blue-light; outline-offset: 2px; }
  &.is-liked {
    color: $subject-pink;
    background: rgba(255, 158, 187, .14);
  }
}

.hero__heart { width: 13px; height: 13px; }
.hero__count { font-variant-numeric: tabular-nums; }

.hero__delBtn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 0;
  background: rgba(255, 255, 255, .07);
  color: rgba(255, 255, 255, .55);
  width: 24px;
  height: 24px;
  border-radius: $r-xs;
  cursor: pointer;

  &:hover { color: $error; background: rgba(194, 54, 26, .14); }
  &:focus-visible { outline: 2px solid $subject-blue-light; outline-offset: 2px; }
}

.hero__icon { width: 13px; height: 13px; }

.hero__resetBtn {
  align-self: flex-end;
  border: 0;
  background: rgba(255, 255, 255, .07);
  color: $subject-blue-light;
  font-size: 11.5px;
  font-weight: 600;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  cursor: pointer;

  &:focus-visible { outline: 2px solid $subject-blue-light; outline-offset: 2px; }
}

.hero__sr {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

@media (max-width: 340px) {
  .hero { padding: $sp-3; }
  .hero__text, .hero__name { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .hero__guide, .hero__cmt { transition: none !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.hero {
  position: relative;
  width: min(92vw, 160vh - 12.8vw);
  aspect-ratio: 480/300;
  margin: 0 auto;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  background: #231f28;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  box-sizing: border-box;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.hero__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex: 1;
}

.hero__cmt {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 8px 12px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 8px;
  will-change: transform, height;
}

.hero__guide {
  position: absolute;
  left: -12px;
  top: 0;
  width: 2px;
  height: 100%;
  background: #5b8cf8;
  opacity: 0.55;
  border-radius: 999px;
  transform: scaleY(0);
  transform-origin: top;
}

.hero__avatar {
  flex: none;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: linear-gradient(160deg, #4cd4a6, #5b8cf8);
}
.hero__avatar--sm {
  width: 20px;
  height: 20px;
  background: linear-gradient(160deg, #6ec8ff, #b9a0ff);
}

.hero__body {
  min-width: 0;
  flex: 1;
}

.hero__meta {
  margin: 0 0 2px;
}

.hero__name {
  color: #fff;
  font-size: 12px;
  font-weight: 700;
}

.hero__text {
  margin: 0 0 4px;
  color: rgba(255, 255, 255, 0.86);
  font-size: 12px;
  line-height: 1.5;
}

.hero__likeBtn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  border: 0;
  background: rgba(255, 255, 255, 0.06);
  color: rgba(255, 255, 255, 0.7);
  padding: 3px 8px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  cursor: pointer;
  margin-right: 4px;
}
.hero__likeBtn:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}
.hero__likeBtn.is-liked {
  color: #ff9ebb;
  background: rgba(255, 158, 187, 0.14);
}

.hero__heart {
  width: 13px;
  height: 13px;
}

.hero__count {
  font-variant-numeric: tabular-nums;
}

.hero__delBtn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 0;
  background: rgba(255, 255, 255, 0.07);
  color: rgba(255, 255, 255, 0.55);
  width: 24px;
  height: 24px;
  border-radius: 4px;
  cursor: pointer;
}
.hero__delBtn:hover {
  color: #c2361a;
  background: rgba(194, 54, 26, 0.14);
}
.hero__delBtn:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.hero__icon {
  width: 13px;
  height: 13px;
}

.hero__resetBtn {
  align-self: flex-end;
  border: 0;
  background: rgba(255, 255, 255, 0.07);
  color: #5b8cf8;
  font-size: 11.5px;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: 999px;
  cursor: pointer;
}
.hero__resetBtn:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.hero__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

@media (max-width: 340px) {
  .hero {
    padding: 12px;
  }
  .hero__text, .hero__name {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .hero__guide, .hero__cmt {
    transition: none !important;
  }
}

(function () {
  // 기법: 하나의 패널에 세 계산이 겹친다. ① 들여쓰기 — data-depth × HERO_REPLY_INDENT_STEP_PX
  // 로 margin-left 를 계산하고 안내선은 scaleY(0→1) 로 위에서 아래로 그린다.
  // ② 좋아요 — 이전/이후 개수 diff 로 자릿수 굴림 방향과 탄성 튐 폭을 계산한다.
  // ③ 삭제 — 행 높이를 실측해 그만큼 접고, 아래 행은 빈 거리를 HERO 스프링 강성으로 메운다.
  var HERO_REPLY_INDENT_STEP_PX = 20;
  var HERO_DELETE_SHIFT_SPRING_STIFFNESS = 220;
  var HERO_LIKE_POP_AMPLITUDE = 1.16;

  // $ease-lerp-settle 곡선(site/static/demo-tokens.scss)과 같은 샘플 — 1 을 넘겼다가(최대 1.126) 되독아온다.
  var SPRING_SETTLE_EASING = 'linear(0.0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1)';

  var root = document.getElementById('heroRoot');
  var list = document.getElementById('heroList');
  var status = document.getElementById('heroStatus');

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (reduce) root.classList.remove('is-demo');

  // ① 들여쓰기 계산
  function applyIndents() {
    var rows = list.querySelectorAll('.hero__cmt');
    for (var i = 0; i < rows.length; i += 1) {
      var depth = parseInt(rows[i].getAttribute('data-depth'), 10);
      rows[i].style.marginLeft = (depth * HERO_REPLY_INDENT_STEP_PX) + 'px';
    }
  }

  function drawGuides(animate, baseDelay) {
    var guides = list.querySelectorAll('.hero__guide');
    for (var i = 0; i < guides.length; i += 1) {
      if (!animate || reduce) {
        guides[i].style.transform = 'scaleY(1)';
        continue;
      }
      guides[i].animate(
        [{ transform: 'scaleY(0)' }, { transform: 'scaleY(1)' }],
        { duration: 440, delay: baseDelay + i * 180, easing: 'ease-out', fill: 'forwards' }
      );
    }
  }

  // ② 좋아요 자릿수 굴림 + 탄성 튐
  function like(btnId, countId, animate, delayMs) {
    var btn = document.getElementById(btnId);
    var countEl = document.getElementById(countId);
    var liked = btn.getAttribute('aria-pressed') === 'true';
    var oldV = parseInt(countEl.textContent, 10);
    var newV = liked ? oldV - 1 : oldV + 1;
    var diff = newV - oldV;

    btn.setAttribute('aria-pressed', String(!liked));
    btn.classList.toggle('is-liked', !liked);
    countEl.textContent = String(newV);
    status.textContent = (!liked ? '좋아요를 눌렀습니다. 좋아요 ' : '좋아요를 취소했습니다. 좋아요 ') + newV + '개';

    if (!animate || reduce) return;

    countEl.animate(
      [
        { transform: 'translateY(0)', opacity: 1 },
        { transform: 'translateY(' + (diff > 0 ? '-70%' : '70%') + ')', opacity: 0 },
        { transform: 'translateY(' + (diff > 0 ? '70%' : '-70%') + ')', opacity: 0, offset: 0.5 },
        { transform: 'translateY(0)', opacity: 1 }
      ],
      { duration: 340, delay: delayMs || 0, easing: 'ease-out' }
    );
    btn.animate(
      [
        { transform: 'scale(1)' },
        { transform: 'scale(' + HERO_LIKE_POP_AMPLITUDE + ')' },
        { transform: 'scale(0.95)' },
        { transform: 'scale(1)' }
      ],
      { duration: 400, delay: delayMs || 0, easing: 'ease-out' }
    );
    // 계산: 좋아요 행 전체에도 diff 크기만큼 옅은 배경 펄스를 얹어 버튼 주변을 넘어선
    // 면적으로 값을 전파한다(item 04 like-pop 의 rowPulse 와 같은 원리).
    var likeRow = btn.closest('.hero__cmt');
    if (likeRow) {
      var pulseAmp = Math.min(0.2, 0.08 + Math.abs(diff) * 0.04);
      likeRow.animate(
        [
          { backgroundColor: 'rgba(255,158,187,0)' },
          { backgroundColor: 'rgba(255,158,187,' + pulseAmp + ')' },
          { backgroundColor: 'rgba(255,158,187,0)' }
        ],
        { duration: 560, delay: delayMs || 0, easing: 'ease-out' }
      );
    }
  }

  // ③ 삭제 접기 + 아래 행 스프링 시프트
  function heroShiftDuration(gapPx) {
    return Math.round(60 + 100000 / HERO_DELETE_SHIFT_SPRING_STIFFNESS + Math.min(220, gapPx * 0.5));
  }

  function removeRow(id, animate, delayMs) {
    var row = list.querySelector('.hero__cmt[data-id="' + id + '"]');
    if (!row || row.getBoundingClientRect().height === 0) return;

    var all = list.querySelectorAll('.hero__cmt');
    var seen = false;
    var below = [];
    for (var i = 0; i < all.length; i += 1) {
      if (all[i] === row) { seen = true; continue; }
      if (seen && all[i].getBoundingClientRect().height > 0) below.push(all[i]);
    }

    var gap = row.offsetHeight + 6;

    if (!animate || reduce) {
      row.style.display = 'none';
      status.textContent = '댓글을 삭제했습니다.';
      return;
    }

    var h = row.offsetHeight;
    row.style.height = h + 'px';
    row.style.overflow = 'hidden';
    row.style.boxSizing = 'border-box';
    row.animate(
      [
        { height: h + 'px', opacity: 1, backgroundColor: 'rgba(194,54,26,0)' },
        { height: h + 'px', opacity: 1, backgroundColor: 'rgba(194,54,26,.16)', offset: 0.4 },
        { height: '0px', opacity: 0, backgroundColor: 'rgba(194,54,26,0)' }
      ],
      { duration: 240, delay: delayMs || 0, easing: 'ease-in', fill: 'forwards' }
    ).onfinish = function () { row.style.display = 'none'; };

    var dur = heroShiftDuration(gap);
    below.forEach(function (el) {
      el.animate(
        [
          { transform: 'translateY(0px)' },
          { transform: 'translateY(' + gap + 'px)' },
          { transform: 'translateY(0px)' }
        ],
        { duration: dur, delay: (delayMs || 0) + 240, easing: SPRING_SETTLE_EASING, fill: 'both' }
      );
      // 계산: 스프링으로 밀려 올라오는 행에도 빈 거리(gap)에 비례한 옅은 배경 결이
      // 같은 시간 동안 함께 지나가 "채워졌다"는 느낌을 면적으로도 보여준다.
      el.animate(
        [
          { backgroundColor: 'rgba(94,234,212,0)' },
          { backgroundColor: 'rgba(94,234,212,' + Math.min(0.18, gap * 0.002) + ')' },
          { backgroundColor: 'rgba(94,234,212,0)' }
        ],
        { duration: dur, delay: (delayMs || 0) + 240, easing: 'ease-out' }
      );
    });
    status.textContent = '댓글을 삭제했습니다.';
  }

  function restoreRows() {
    var rows = list.querySelectorAll('.hero__cmt');
    for (var i = 0; i < rows.length; i += 1) {
      rows[i].getAnimations().forEach(function (a) { a.cancel(); });
      rows[i].style.display = '';
      rows[i].style.height = '';
      rows[i].style.overflow = '';
    }
    status.textContent = '되돌렸습니다.';
  }

  function bindLike(btnId, countId) {
    var btn = document.getElementById(btnId);
    btn.addEventListener('click', function () {
      root.classList.remove('is-demo');
      like(btnId, countId, true, 0);
    });
    btn.addEventListener('keydown', function (e) {
      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); btn.click(); }
    });
  }

  function bindDelete(btnId, targetId) {
    var btn = document.getElementById(btnId);
    btn.addEventListener('click', function () {
      root.classList.remove('is-demo');
      removeRow(targetId, true, 0);
    });
    btn.addEventListener('keydown', function (e) {
      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); btn.click(); }
    });
  }

  bindLike('heroLike1', 'heroCount1');
  bindLike('heroLike4', 'heroCount4');
  bindDelete('heroDel1', 'h1');
  bindDelete('heroDel4', 'h4');

  var reset = document.getElementById('heroReset');
  reset.addEventListener('click', function () {
    root.classList.remove('is-demo');
    restoreRows();
  });
  reset.addEventListener('keydown', function (e) {
    if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); reset.click(); }
  });

  applyIndents();

  if (reduce) {
    drawGuides(false, 0);
  } else {
    // 데모 시퀀스: 안내선 그리기(220ms~) → 좋아요 튐(900ms~) → 삭제 접힘(1150ms~, 스프링까지 2s 안에 담기게)
    drawGuides(true, 220);
    like('heroLike1', 'heroCount1', true, 900);
    removeRow('h4', true, 1150);
  }
})();

import { useEffect, useRef } from "react";
import styles from "./CommentThreadHeroPanelScene.module.scss";

// 기법: 하나의 패널에 세 계산이 겹친다. ① 들여쓰기 — data-depth × HERO_REPLY_INDENT_STEP_PX
// 로 margin-left 를 계산하고 안내선은 scaleY(0→1) 로 위에서 아래로 그린다.
// ② 좋아요 — 이전/이후 개수 diff 로 자릿수 굴림 방향과 탄성 튐 폭을 계산한다.
// ③ 삭제 — 행 높이를 실측해 그만큼 접고, 아래 행은 빈 거리를 HERO 스프링 강성으로 메운다.
const HERO_REPLY_INDENT_STEP_PX = 20;
const HERO_DELETE_SHIFT_SPRING_STIFFNESS = 220;
const HERO_LIKE_POP_AMPLITUDE = 1.16;

// $ease-lerp-settle 곡선(site/static/demo-tokens.scss)과 같은 샘플 — 1 을 넘겼다가(최대 1.126) 되독아온다.
const SPRING_SETTLE_EASING =
  "linear(0.0, 0.051, 0.176, 0.341, 0.518, 0.685, 0.831, 0.947, 1.032, 1.087, 1.117, 1.126, 1.121, 1.105, 1.085, 1.062, 1.041, 1.022, 1.008, 0.997, 1)";

const HEART_SVG = (
  <svg className={styles.hero__heart} viewBox="0 0 256 256" aria-hidden="true">
    <g fill="currentColor">
      <path d="M232 102c0 66-104 122-104 122S24 168 24 102a54 54 0 0 1 54-54c22.59 0 41.94 12.31 50 32c8.06-19.69 27.41-32 50-32a54 54 0 0 1 54 54" opacity=".2" />
      <path d="M178 40c-20.65 0-38.73 8.88-50 23.89C116.73 48.88 98.65 40 78 40a62.07 62.07 0 0 0-62 62c0 70 103.79 126.66 108.21 129a8 8 0 0 0 7.58 0C136.21 228.66 240 172 240 102a62.07 62.07 0 0 0-62-62m-50 174.8c-18.26-10.64-96-59.11-96-112.8a46.06 46.06 0 0 1 46-46c19.45 0 35.78 10.36 42.6 27a8 8 0 0 0 14.8 0c6.82-16.67 23.15-27 42.6-27a46.06 46.06 0 0 1 46 46c0 53.61-77.76 102.15-96 112.8" />
    </g>
  </svg>
);

const TRASH_SVG = (
  <svg className={styles.hero__icon} viewBox="0 0 256 256" aria-hidden="true">
    <g fill="currentColor">
      <path d="M200 56v152a8 8 0 0 1-8 8H64a8 8 0 0 1-8-8V56Z" opacity=".2" />
      <path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16M96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0m48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0" />
    </g>
  </svg>
);

export default function CommentThreadHeroPanelScene() {
  const rootRef = useRef<HTMLDivElement>(null);
  const listRef = useRef<HTMLUListElement>(null);
  const statusRef = useRef<HTMLParagraphElement>(null);
  const likeRefs = useRef<Record<string, HTMLButtonElement | null>>({});
  const countRefs = useRef<Record<string, HTMLSpanElement | null>>({});

  useEffect(() => {
    const root = rootRef.current;
    const list = listRef.current;
    const status = statusRef.current;
    if (!root || !list || !status) return;

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (reduce) root.classList.remove("is-demo");

    function applyIndents() {
      const rows = list!.querySelectorAll<HTMLElement>(".hero__cmt");
      rows.forEach((row) => {
        const depth = parseInt(row.getAttribute("data-depth")!, 10);
        row.style.marginLeft = `${depth * HERO_REPLY_INDENT_STEP_PX}px`;
      });
    }

    function drawGuides(animate: boolean, baseDelay: number) {
      const guides = list!.querySelectorAll<HTMLElement>(".hero__guide");
      guides.forEach((g, i) => {
        if (!animate || reduce) {
          g.style.transform = "scaleY(1)";
          return;
        }
        g.animate(
          [{ transform: "scaleY(0)" }, { transform: "scaleY(1)" }],
          { duration: 440, delay: baseDelay + i * 180, easing: "ease-out", fill: "forwards" }
        );
      });
    }

    function like(key: string, animate: boolean, delayMs: number) {
      const btn = likeRefs.current![key];
      const countEl = countRefs.current![key];
      if (!btn || !countEl) return;
      const liked = btn.getAttribute("aria-pressed") === "true";
      const oldV = parseInt(countEl.textContent!, 10);
      const newV = liked ? oldV - 1 : oldV + 1;
      const diff = newV - oldV;

      btn.setAttribute("aria-pressed", String(!liked));
      btn.classList.toggle("is-liked", !liked);
      countEl.textContent = String(newV);
      status!.textContent = (!liked ? "좋아요를 눌렀습니다. 좋아요 " : "좋아요를 취소했습니다. 좋아요 ") + newV + "개";

      if (!animate || reduce) return;

      countEl.animate(
        [
          { transform: "translateY(0)", opacity: 1 },
          { transform: `translateY(${diff > 0 ? "-70%" : "70%"})`, opacity: 0 },
          { transform: `translateY(${diff > 0 ? "70%" : "-70%"})`, opacity: 0, offset: 0.5 },
          { transform: "translateY(0)", opacity: 1 },
        ],
        { duration: 340, delay: delayMs, easing: "ease-out" }
      );
      btn.animate(
        [
          { transform: "scale(1)" },
          { transform: `scale(${HERO_LIKE_POP_AMPLITUDE})` },
          { transform: "scale(0.95)" },
          { transform: "scale(1)" },
        ],
        { duration: 400, delay: delayMs, easing: "ease-out" }
      );
      // 계산: 좋아요 행 전체에도 diff 크기만큼 옅은 배경 펄스를 얹어 버튼 주변을 넘어선
      // 면적으로 값을 전파한다(item 04 like-pop 의 rowPulse 와 같은 원리).
      const likeRow = btn.closest<HTMLElement>(".hero__cmt");
      if (likeRow) {
        const pulseAmp = Math.min(0.2, 0.08 + Math.abs(diff) * 0.04);
        likeRow.animate(
          [
            { backgroundColor: "rgba(255,158,187,0)" },
            { backgroundColor: `rgba(255,158,187,${pulseAmp})` },
            { backgroundColor: "rgba(255,158,187,0)" },
          ],
          { duration: 560, delay: delayMs, easing: "ease-out" }
        );
      }
    }

    function heroShiftDuration(gapPx: number): number {
      return Math.round(60 + 100000 / HERO_DELETE_SHIFT_SPRING_STIFFNESS + Math.min(220, gapPx * 0.5));
    }

    function removeRow(id: string, animate: boolean, delayMs: number) {
      const row = list!.querySelector<HTMLElement>(`.hero__cmt[data-id="${id}"]`);
      if (!row || row.getBoundingClientRect().height === 0) return;

      const all = Array.from(list!.querySelectorAll<HTMLElement>(".hero__cmt"));
      const seen = all.indexOf(row);
      const below = all.slice(seen + 1).filter((el) => el.getBoundingClientRect().height > 0);

      const gap = row.offsetHeight + 6;

      if (!animate || reduce) {
        row.style.display = "none";
        status!.textContent = "댓글을 삭제했습니다.";
        return;
      }

      const h = row.offsetHeight;
      row.style.height = h + "px";
      row.style.overflow = "hidden";
      row.style.boxSizing = "border-box";
      const collapse = row.animate(
        [
          { height: h + "px", opacity: 1, backgroundColor: "rgba(194,54,26,0)" },
          { height: h + "px", opacity: 1, backgroundColor: "rgba(194,54,26,.16)", offset: 0.4 },
          { height: "0px", opacity: 0, backgroundColor: "rgba(194,54,26,0)" },
        ],
        { duration: 240, delay: delayMs, easing: "ease-in", fill: "forwards" }
      );
      collapse.onfinish = () => { row.style.display = "none"; };

      const dur = heroShiftDuration(gap);
      below.forEach((el) => {
        el.animate(
          [
            { transform: "translateY(0px)" },
            { transform: `translateY(${gap}px)` },
            { transform: "translateY(0px)" },
          ],
          { duration: dur, delay: delayMs + 240, easing: SPRING_SETTLE_EASING, fill: "both" }
        );
        // 계산: 스프링으로 밀려 올라오는 행에도 빈 거리(gap)에 비례한 옅은 배경 결이
        // 같은 시간 동안 함께 지나가 "채워졌다"는 느낌을 면적으로도 보여준다.
        el.animate(
          [
            { backgroundColor: "rgba(94,234,212,0)" },
            { backgroundColor: `rgba(94,234,212,${Math.min(0.18, gap * 0.002)})` },
            { backgroundColor: "rgba(94,234,212,0)" },
          ],
          { duration: dur, delay: delayMs + 240, easing: "ease-out" }
        );
      });
      status!.textContent = "댓글을 삭제했습니다.";
    }

    function restoreRows() {
      const rows = list!.querySelectorAll<HTMLElement>(".hero__cmt");
      rows.forEach((row) => {
        row.getAnimations().forEach((a) => a.cancel());
        row.style.display = "";
        row.style.height = "";
        row.style.overflow = "";
      });
      status!.textContent = "되돌렸습니다.";
    }

    function bindLike(key: string) {
      const btn = likeRefs.current![key];
      if (!btn) return;
      const onActivate = () => { root!.classList.remove("is-demo"); like(key, true, 0); };
      btn.addEventListener("click", onActivate);
      btn.addEventListener("keydown", (e) => {
        if (e.key === "Enter" || e.key === " ") { e.preventDefault(); onActivate(); }
      });
    }

    function bindDelete(btnId: string, targetId: string) {
      const btn = document.getElementById(btnId);
      if (!btn) return;
      const onActivate = () => { root!.classList.remove("is-demo"); removeRow(targetId, true, 0); };
      btn.addEventListener("click", onActivate);
      btn.addEventListener("keydown", (e) => {
        if (e.key === "Enter" || e.key === " ") { e.preventDefault(); onActivate(); }
      });
    }

    bindLike("h1");
    bindLike("h4");
    bindDelete("heroDel1", "h1");
    bindDelete("heroDel4", "h4");
    const reset = document.getElementById("heroReset");
    const onReset = () => { root!.classList.remove("is-demo"); restoreRows(); };
    reset?.addEventListener("click", onReset);
    reset?.addEventListener("keydown", (e) => {
      if (e.key === "Enter" || e.key === " ") { e.preventDefault(); onReset(); }
    });

    applyIndents();

    if (reduce) {
      drawGuides(false, 0);
    } else {
      drawGuides(true, 220);
      like("h1", true, 900);
      removeRow("h4", true, 1150);
    }
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.hero} is-demo`} ref={rootRef}>
        <ul className={styles.hero__list} role="list" ref={listRef}>
          <li className={`hero__cmt ${styles.hero__cmt}`} data-depth="0" data-id="h1">
            <span className={styles.hero__avatar} aria-hidden="true" />
            <div className={styles.hero__body}>
              <p className={styles.hero__meta}><strong className={styles.hero__name}>노을빛선장</strong></p>
              <p className={styles.hero__text}>세 가지 움직임이 한 패널에 섞였어요.</p>
              <button type="button" className={`hero__likeBtn ${styles.hero__likeBtn}`} ref={(el: HTMLButtonElement | null) => { likeRefs.current!["h1"] = el; }} aria-pressed="false" aria-label="좋아요">
                {HEART_SVG}
                <span className={styles.hero__count} ref={(el: HTMLSpanElement | null) => { countRefs.current!["h1"] = el; }}>187</span>
              </button>
              <button type="button" className={`hero__delBtn ${styles.hero__delBtn}`} id="heroDel1" aria-label="댓글 삭제">
                {TRASH_SVG}
              </button>
            </div>
          </li>
          <li className={`hero__cmt ${styles.hero__cmt}`} data-depth="1" data-id="h2">
            <span className={`hero__guide ${styles.hero__guide}`} aria-hidden="true" />
            <span className={`${styles.hero__avatar} ${styles["hero__avatar--sm"]}`} aria-hidden="true" />
            <div className={styles.hero__body}>
              <p className={styles.hero__meta}><strong className={styles.hero__name}>무지개다리</strong></p>
              <p className={styles.hero__text}>답글 들여쓰기가 깊이에 비례해서 밀리네요.</p>
            </div>
          </li>
          <li className={`hero__cmt ${styles.hero__cmt}`} data-depth="2" data-id="h3">
            <span className={`hero__guide ${styles.hero__guide}`} aria-hidden="true" />
            <span className={`${styles.hero__avatar} ${styles["hero__avatar--sm"]}`} aria-hidden="true" />
            <div className={styles.hero__body}>
              <p className={styles.hero__meta}><strong className={styles.hero__name}>이슬털기</strong></p>
              <p className={styles.hero__text}>대댓글 안내선은 위에서 아래로 그려지고.</p>
            </div>
          </li>
          <li className={`hero__cmt ${styles.hero__cmt}`} data-depth="0" data-id="h4">
            <span className={styles.hero__avatar} aria-hidden="true" />
            <div className={styles.hero__body}>
              <p className={styles.hero__meta}><strong className={styles.hero__name}>바위틈새</strong></p>
              <p className={styles.hero__text}>이 댓글을 삭제하면 아래가 스프링으로 올라와요.</p>
              <button type="button" className={`hero__likeBtn ${styles.hero__likeBtn}`} ref={(el: HTMLButtonElement | null) => { likeRefs.current!["h4"] = el; }} aria-pressed="false" aria-label="좋아요">
                {HEART_SVG}
                <span className={styles.hero__count} ref={(el: HTMLSpanElement | null) => { countRefs.current!["h4"] = el; }}>94</span>
              </button>
              <button type="button" className={`hero__delBtn ${styles.hero__delBtn}`} id="heroDel4" aria-label="댓글 삭제">
                {TRASH_SVG}
              </button>
            </div>
          </li>
        </ul>
        <button type="button" className={styles.hero__resetBtn} id="heroReset">되돌리기</button>
        <p className={styles.hero__sr} ref={statusRef} aria-live="polite" />
      </div>
    </main>
  );
}