09업로드 뒤 재정렬 — 완료된 칩을 손으로 다시 배열하는 마무리

<main class="stage">
<div class="rq" id="rq">
  <p class="rq__hint" id="rqHint">읽기가 끝난 파일들은 순서를 다시 꾸릴 수 있습니다 — 포인터로 집어 옮기면 끼워 넣을 칸을 계산합니다</p>
  <div class="rq__zone" id="rqZone" role="button" tabindex="0" aria-describedby="rqHint" aria-label="파일 드롭존">
    <input type="file" id="rqInput" multiple class="rq__file" aria-label="파일 선택">
    <svg class="rq__ic" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M208 32v192a16 16 0 0 1-16 16H64a16 16 0 0 1-16-16V32a16 16 0 0 1 16-16h128a16 16 0 0 1 16 16" opacity=".2"/><path d="M104 60a12 12 0 1 1-12-12a12 12 0 0 1 12 12m60 12a12 12 0 1 0-12-12a12 12 0 0 0 12 12m-72 44a12 12 0 1 0 12 12a12 12 0 0 0-12-12m72 0a12 12 0 1 0 12 12a12 12 0 0 0-12-12m-72 68a12 12 0 1 0 12 12a12 12 0 0 0-12-12m72 0a12 12 0 1 0 12 12a12 12 0 0 0-12-12"/></g></svg>
  </div>
  <ul class="rq__list" id="rqList" aria-label="읽기 완료 파일 목록"></ul>
  <div class="rq__meta">
    <span class="rq__tag" id="rqTag">done 0</span>
    <span class="rq__unit" id="rqUnit">order —</span>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;

$duration: 240ms;      // 칩 자리 이동(FLIP transform)
$easing: $ease-spring;
$color: $subject-ink;

// 파스텔 강조(채도 .34 · 명도 +.11)
$p-creamline: #f6eede;
$p-mint: #93d9c0;

@include stage($stage-yellow);

.rq {
  width: 100%;
  max-width: 380px;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}

.rq__hint {
  margin: 0;
  padding: 0 $sp-1;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.4;
  color: $subject-ink;
}

.rq__zone {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 44px;
  padding: $sp-2 $sp-3;
  border: 2px dashed rgba($subject-ink, .72);
  border-radius: $r-card;
  cursor: pointer;
  overflow: hidden;
  transition: border-color $dur-quick $ease-out, background $dur-quick $ease-out;
}

.rq__zone.is-over {
  border-color: $p-mint;
  background: rgba(147, 217, 192, .14);
}

.rq__file {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
}

.rq__ic {
  width: 22px;
  height: 22px;
  color: $subject-ink;
  transition: transform $dur-quick $ease-pop;
}

.rq__zone.is-over .rq__ic {
  transform: scale(1.15);
}

.rq__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: $sp-1;
  min-height: 76px;
}

.rq__chip {
  display: flex;
  align-items: center;
  gap: $sp-1;
  padding: $sp-1 $sp-2;
  border-radius: $r-sm;
  border: 2px solid rgba($subject-ink, .25);
  background: rgba($subject-ink, .05);
  transition: transform $duration $easing, border-color $dur-quick $ease-out,
    background $dur-quick $ease-out, opacity $dur-quick $ease-out;
  touch-action: none;
}

.rq__chip.is-done {
  border-color: $subject-ink;
  cursor: grab;
}

.rq__chip.is-drag {
  opacity: .85;
  border-color: $subject-blue-deep;
  background: rgba($subject-ink, .1);
  cursor: grabbing;
}

.rq__dot {
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  border-radius: 50%;
}

.rq__name {
  font-weight: 500;
  font-size: 11px;
  color: $subject-ink;
  white-space: nowrap;
}

.rq__badge {
  flex: 0 0 auto;
  padding: $sp-1;
  border-radius: $r-xs;
  font-weight: 700;
  font-size: 9px;
  line-height: 1.2;
  color: rgba($subject-ink, .72);
  background: rgba($subject-ink, .08);
}

.rq__chip.is-done .rq__badge {
  color: $p-creamline;
  background: $subject-ink;
}

.rq__meta {
  display: flex;
  align-items: baseline;
  gap: $sp-2;
  padding: 0 $sp-1;
}

.rq__tag {
  font-weight: 700;
  font-size: 12px;
  color: $subject-ink;
}

.rq__unit {
  min-width: 0;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  font-weight: 400;
  font-size: 10px;
  color: rgba($subject-ink, .72);
}

@media (max-width: 340px) {
  .rq { max-width: 270px; gap: $sp-1; }
  .rq__hint { font-size: 9px; line-height: 1.25; }
  .rq__zone { min-height: 28px; padding: $sp-1 $sp-2; }
  .rq__ic { width: 18px; height: 18px; }
  .rq__name { font-size: 10px; }
  .rq__list { min-height: 44px; gap: $sp-1; }
  .rq__chip { padding: $sp-1; }
}

@media (prefers-reduced-motion: reduce) {
  .rq__chip { transition: none; }
  .rq__zone, .rq__ic { transition: none; }
  .rq__zone.is-over .rq__ic { transform: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.rq {
  width: 100%;
  max-width: 380px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.rq__hint {
  margin: 0;
  padding: 0 4px;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.4;
  color: #17141a;
}

.rq__zone {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 44px;
  padding: 8px 12px;
  border: 2px dashed rgba(23, 20, 26, 0.72);
  border-radius: 16px;
  cursor: pointer;
  overflow: hidden;
  transition: border-color 220ms ease-out, background 220ms ease-out;
}

.rq__zone.is-over {
  border-color: #93d9c0;
  background: rgba(147, 217, 192, 0.14);
}

.rq__file {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
}

.rq__ic {
  width: 22px;
  height: 22px;
  color: #17141a;
  transition: transform 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}

.rq__zone.is-over .rq__ic {
  transform: scale(1.15);
}

.rq__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  min-height: 76px;
}

.rq__chip {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px 8px;
  border-radius: 8px;
  border: 2px solid rgba(23, 20, 26, 0.25);
  background: rgba(23, 20, 26, 0.05);
  transition: transform 240ms cubic-bezier(0.2, 0.8, 0.2, 1), border-color 220ms ease-out, background 220ms ease-out, opacity 220ms ease-out;
  touch-action: none;
}

.rq__chip.is-done {
  border-color: #17141a;
  cursor: grab;
}

.rq__chip.is-drag {
  opacity: 0.85;
  border-color: #0a4fe8;
  background: rgba(23, 20, 26, 0.1);
  cursor: grabbing;
}

.rq__dot {
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  border-radius: 50%;
}

.rq__name {
  font-weight: 500;
  font-size: 11px;
  color: #17141a;
  white-space: nowrap;
}

.rq__badge {
  flex: 0 0 auto;
  padding: 4px;
  border-radius: 4px;
  font-weight: 700;
  font-size: 9px;
  line-height: 1.2;
  color: rgba(23, 20, 26, 0.72);
  background: rgba(23, 20, 26, 0.08);
}

.rq__chip.is-done .rq__badge {
  color: #f6eede;
  background: #17141a;
}

.rq__meta {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 0 4px;
}

.rq__tag {
  font-weight: 700;
  font-size: 12px;
  color: #17141a;
}

.rq__unit {
  min-width: 0;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  font-weight: 400;
  font-size: 10px;
  color: rgba(23, 20, 26, 0.72);
}

@media (max-width: 340px) {
  .rq {
    max-width: 270px;
    gap: 4px;
  }
  .rq__hint {
    font-size: 9px;
    line-height: 1.25;
  }
  .rq__zone {
    min-height: 28px;
    padding: 4px 8px;
  }
  .rq__ic {
    width: 18px;
    height: 18px;
  }
  .rq__name {
    font-size: 10px;
  }
  .rq__list {
    min-height: 44px;
    gap: 4px;
  }
  .rq__chip {
    padding: 4px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .rq__chip {
    transition: none;
  }
  .rq__zone, .rq__ic {
    transition: none;
  }
  .rq__zone.is-over .rq__ic {
    transform: none;
  }
}

// 업로드 후 재정렬(09) — '읽기 완료' 상태가 된 파일 칩을 pointerdown 으로 집어 옮긴다.
// 포인터 x 와 각 칩 getBoundingClientRect().left+width/2 를 비교해 끼워 넣을 칸 인덱스를
// 계산하고, 순서 배열이 바뀌면 트랜지션으로 자리를 다시 꾸린다(FLIP: 이전·이후 위치 차이를
// transform 으로 되돌렸다 푼다). 드롭 → '읽는 중' 짧은 단계 → done 배지 → 재정렬 가능.
(function () {
  var zone = document.getElementById('rqZone');
  var input = document.getElementById('rqInput');
  var listEl = document.getElementById('rqList');
  var tagEl = document.getElementById('rqTag');
  var unitEl = document.getElementById('rqUnit');
  if (!zone || !input || !listEl || !tagEl || !unitEl) return;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  function mulberry32(a) {
    return function () {
      a |= 0; a = a + 0x6D2B79F5 | 0;
      var t = Math.imul(a ^ a >>> 15, 1 | a);
      t = t + Math.imul(t ^ t >>> 7, 61 | t) ^ t;
      return ((t ^ t >>> 14) >>> 0) / 4294967296;
    };
  }
  var rnd = mulberry32(909);
  var HEXES = ['#d6e1eb', '#93d9c0', '#b9a0ff', '#f6c6d3', '#f0dfae'];

  var NAMES = ['cover.png', 'hero.jpg', 'shot-03.png', 'inline.gif'];
  var chips = [];      // { name, state:'reading'|'done', el }
  var order = [];      // 현재 순서(인덱스)

  // FLIP: 재배치 전 각 칩의 위치를 기억 → DOM 순서 반영 → 차이만큼 transform 되돌리기 → 풀기
  function relayout() {
    var rects = order.map(function (i) { return chips[i].el.getBoundingClientRect(); });
    order.forEach(function (i, k) { listEl.appendChild(chips[i].el); });
    order.forEach(function (i, k) {
      var now = chips[i].el.getBoundingClientRect();
      var dx = rects[k].left - now.left;
      var el = chips[i].el;
      if (!dx) return;
      if (reduce) return;
      el.style.transition = 'none';
      el.style.transform = 'translateX(' + dx + 'px)';
      void el.offsetWidth;
      el.style.transition = '';
      el.style.transform = '';
    });
    unitEl.textContent = 'order ' + order.map(function (i) { return chips[i].name; }).join(' › ');
    var done = order.filter(function (i) { return chips[i].state === 'done'; }).length;
    tagEl.textContent = 'done ' + done + '/' + chips.length;
  }

  function insertionIndex(x) {
    var idx = order.length;
    for (var k = 0; k < order.length; k++) {
      var r = chips[order[k]].el.getBoundingClientRect();
      if (x < r.left + r.width / 2) { idx = k; break; }   // 각 칸 중점과 비교
    }
    return idx;
  }

  // 칩 집기 — pointerdown 으로 시작, 움직이면 끼워 넣을 칸을 계산해 순서를 바꾼다
  function armDrag(el, self) {
    el.addEventListener('pointerdown', function (e) {
      if (chips[self] && chips[self].state !== 'done') return;   // 읽는 중엔 잠김
      el.setPointerCapture(e.pointerId);
      el.classList.add('is-drag');
      var move = function (ev) {
        var to = insertionIndex(ev.clientX);
        var from = order.indexOf(self);
        if (to !== from && to !== from + 1) {
          order.splice(from, 1);
          order.splice(to > from ? to - 1 : to, 0, self);
          relayout();
        }
      };
      var up = function () {
        el.classList.remove('is-drag');
        el.removeEventListener('pointermove', move);
        el.removeEventListener('pointerup', up);
        el.removeEventListener('pointercancel', up);
      };
      el.addEventListener('pointermove', move);
      el.addEventListener('pointerup', up);
      el.addEventListener('pointercancel', up);
    });
  }

  function addChip(name) {
    if (chips.length >= 4) {
      var drop = order.shift();
      chips[drop].el.remove();
      chips[drop] = null;
    }
    var i = chips.length ? chips.length : 0;
    var li = document.createElement('li');
    li.className = 'rq__chip is-reading';
    li.setAttribute('role', 'listitem');
    var dot = document.createElement('span');
    dot.className = 'rq__dot';
    dot.style.background = HEXES[Math.floor(rnd() * HEXES.length)];
    var nm = document.createElement('span');
    nm.className = 'rq__name';
    nm.textContent = name;
    var badge = document.createElement('span');
    badge.className = 'rq__badge';
    badge.textContent = '읽는 중';
    li.appendChild(dot); li.appendChild(nm); li.appendChild(badge);
    listEl.appendChild(li);
    chips[i] = { name: name, state: 'reading', el: li };
    order.push(i);
    relayout();
    armDrag(li, i);
    var settle = function () {
      chips[i].state = 'done';
      li.classList.remove('is-reading');
      li.classList.add('is-done');
      badge.textContent = 'done';
      relayout();
    };
    if (reduce) settle();
    else setTimeout(settle, 500);
  }

  // 실제 드롭 — File 이름으로 같은 파이프라인
  zone.addEventListener('dragover', function (e) { e.preventDefault(); zone.classList.add('is-over'); });
  zone.addEventListener('dragleave', function () { zone.classList.remove('is-over'); });
  zone.addEventListener('drop', function (e) {
    e.preventDefault(); zone.classList.remove('is-over');
    var fs = e.dataTransfer && e.dataTransfer.files;
    if (fs && fs.length) {
      for (var i = 0; i < Math.min(fs.length, 2); i++) addChip(fs[i].name);
    }
  });
  input.addEventListener('change', function () {
    var fs = input.files;
    if (fs && fs.length) {
      for (var i = 0; i < Math.min(fs.length, 2); i++) addChip(fs[i].name);
    }
    input.value = '';
  });

  // 자동 시연 — 파일이 들어오고 done 이 되면 스스로 순서를 바꿔본다(같은 relayout 경로)
  if (reduce) {
    addChip(NAMES[0]); addChip(NAMES[1]);
    setTimeout(function () {
      order.reverse();
      relayout();
    }, 40);
  } else {
    var phase = 0, nextAt = 0;
    (function loop(now) {
      if (now >= nextAt) {
        if (phase < 4) {
          addChip(NAMES[phase]);
          nextAt = now + 640;
        } else {
          var from = Math.floor(rnd() * order.length);
          order.splice(0, 0, order.splice(from, 1)[0]);   // 무작위 칩을 맨 앞으로
          relayout();
          nextAt = now + 900;
        }
        phase++;
      }
      requestAnimationFrame(loop);
    })(0);
  }
})();

// DropReorderAfterUpload — vanilla 판(run/337/demo/09-drop-reorder-after-upload/index.html) 의
// React 포트. FLIP(First-Last-Invert-Play) 로 재배치를 부드럽게 잇는다: 재배치 전 각 칩의
// getBoundingClientRect() 를 먼저 찍고, DOM 순서를 바꾼 뒤 새 위치와의 차(dx)를 역방향
// transform 으로 즉시 걸어 리플로우로 확정한 다음 그 transform 을 지워 CSS 전환이 0 으로
// 되돌아가며 애니메이션되게 한다.
import { useEffect, useRef } from "react";
import styles from "./DropReorderAfterUpload.module.scss";

export type DropReorderAfterUploadProps = {
  duration?: string;
  easing?: string;
  color?: string;
};

type Box<T> = { current: T };

const HINT = "업로드 완료 뒤에도 드래그로 순서를 바꿀 수 있습니다 — FLIP 으로 위치 이동을 계산해 잇습니다";
const ARIA_LABEL = "업로드 후 재정렬 드롭존";

function mulberry32(a: number): () => number {
  return function (): number {
    a |= 0; a = a + 0x6d2b79f5 | 0;
    let t = Math.imul(a ^ a >>> 15, 1 | a);
    t = t + Math.imul(t ^ t >>> 7, 61 | t) ^ t;
    return ((t ^ t >>> 14) >>> 0) / 4294967296;
  };
}

const HEXES = ["#9fc9ec", "#93d9c0", "#b9a0ff", "#f6c6d3", "#cfd8f5"];
const NAMES = ["cover.png", "profile.jpg", "banner.png", "thumb.jpg"];
const MAX_CHIPS = 4;
const SETTLE_MS = 500;

type Chip = { name: string; state: "reading" | "done"; el: HTMLLIElement };

export default function DropReorderAfterUpload({
  duration = "240ms",
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#17141a"
}: DropReorderAfterUploadProps) {
  const zoneRef = useRef<HTMLDivElement | null>(null);
  const inputRef = useRef<HTMLInputElement | null>(null);
  const listRef = useRef<HTMLUListElement | null>(null);
  const tagRef = useRef<HTMLSpanElement | null>(null);
  const unitRef = useRef<HTMLSpanElement | null>(null);
  const rafRef = useRef(0) as Box<number>;

  useEffect(() => {
    const zone = zoneRef.current;
    const input = inputRef.current;
    const listEl = listRef.current;
    const tagEl = tagRef.current;
    const unitEl = unitRef.current;
    if (!zone || !input || !listEl || !tagEl || !unitEl) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const rnd = mulberry32(909);

    let chips: (Chip | null)[] = [];
    let order: number[] = [];
    const settleTimers: number[] = [];

    // FLIP — 재배치 전 rect 를 찍고, DOM 순서를 바꾼 뒤 이전 위치와의 차를 되돌려 걸었다가 지운다
    function relayout(): void {
      const rects = new Map<number, DOMRect>();
      order.forEach((idx) => {
        const c = chips[idx];
        if (c) rects.set(idx, c.el.getBoundingClientRect());
      });
      order.forEach((idx) => {
        const c = chips[idx];
        if (c) listEl!.appendChild(c.el);
      });
      order.forEach((idx) => {
        const c = chips[idx];
        if (!c) return;
        const before = rects.get(idx);
        if (!before) return;
        const now = c.el.getBoundingClientRect();
        const dx = before.left - now.left;
        if (Math.abs(dx) > 0.5 && !reduce) {
          c.el.style.transition = "none";
          c.el.style.transform = "translateX(" + dx + "px)";
          void c.el.offsetWidth;
          c.el.style.transition = "";
          c.el.style.transform = "";
        }
      });
      const doneCount = chips.filter((c) => c && c.state === "done").length;
      const alive = chips.filter((c): c is Chip => !!c);
      unitEl!.textContent = "order " + order.map((idx) => (chips[idx] ? chips[idx]!.name : "")).join(" › ");
      tagEl!.textContent = "done " + doneCount + "/" + alive.length;
    }

    function insertionIndex(x: number): number {
      for (let i = 0; i < order.length; i++) {
        const c = chips[order[i]];
        if (!c) continue;
        const r = c.el.getBoundingClientRect();
        const mid = r.left + r.width / 2;
        if (x < mid) return i;
      }
      return order.length;
    }

    function armDrag(el: HTMLLIElement, self: number): void {
      let dragging = false;
      function onDown(e: PointerEvent): void {
        const c = chips[self];
        if (!c || c.state !== "done") return;
        dragging = true;
        try { el.setPointerCapture(e.pointerId); } catch (err) { /* noop */ }
        el.classList.add(styles.chipDrag);
        el.addEventListener("pointermove", onMove as EventListener);
        el.addEventListener("pointerup", onUp as EventListener);
        el.addEventListener("pointercancel", onUp as EventListener);
      }
      function onMove(e: PointerEvent): void {
        if (!dragging) return;
        const to = insertionIndex(e.clientX);
        const from = order.indexOf(self);
        if (to !== from && to !== from + 1) {
          const moved = order.splice(from, 1)[0];
          const adj = to > from ? to - 1 : to;
          order.splice(adj, 0, moved);
          relayout();
        }
      }
      function onUp(): void {
        dragging = false;
        el.classList.remove(styles.chipDrag);
        el.removeEventListener("pointermove", onMove as EventListener);
        el.removeEventListener("pointerup", onUp as EventListener);
        el.removeEventListener("pointercancel", onUp as EventListener);
      }
      el.addEventListener("pointerdown", onDown as EventListener);
    }

    function addChip(name: string): void {
      if (chips.filter((c) => c).length >= MAX_CHIPS) {
        const oldestIdx = order.shift();
        if (oldestIdx !== undefined) {
          const old = chips[oldestIdx];
          if (old) old.el.remove();
          chips[oldestIdx] = null;
        }
      }
      const idx = chips.length;
      const li = document.createElement("li");
      li.className = styles.chip + " " + styles.chipReading;
      const dot = document.createElement("span");
      dot.className = styles.dot;
      dot.style.background = HEXES[Math.floor(rnd() * HEXES.length)];
      const nm = document.createElement("span");
      nm.className = styles.name;
      nm.textContent = name;
      const badge = document.createElement("span");
      badge.className = styles.badge;
      badge.textContent = "읽는 중";
      li.appendChild(dot); li.appendChild(nm); li.appendChild(badge);
      const chip: Chip = { name, state: "reading", el: li };
      chips.push(chip);
      order.push(idx);
      listEl!.appendChild(li);
      relayout();
      armDrag(li, idx);
      const settle = (): void => {
        chip.state = "done";
        li.className = styles.chip + " " + styles.chipDone;
        badge.textContent = "done";
        relayout();
      };
      if (reduce) settle();
      else settleTimers.push(window.setTimeout(settle, SETTLE_MS));
    }

    function onOver(e: DragEvent): void {
      e.preventDefault();
      zone!.classList.add(styles.zoneOver);
    }
    function onLeave(): void {
      zone!.classList.remove(styles.zoneOver);
    }
    function onDrop(e: DragEvent): void {
      e.preventDefault();
      zone!.classList.remove(styles.zoneOver);
      const files = e.dataTransfer && e.dataTransfer.files;
      if (files) Array.prototype.slice.call(files, 0, 2).forEach((f: File) => addChip(f.name));
    }
    function onChange(): void {
      const files = input!.files;
      if (files) Array.prototype.slice.call(files, 0, 2).forEach((f: File) => addChip(f.name));
      input!.value = "";
    }
    zone.addEventListener("dragover", onOver as EventListener);
    zone.addEventListener("dragleave", onLeave);
    zone.addEventListener("drop", onDrop as EventListener);
    input.addEventListener("change", onChange);

    if (reduce) {
      addChip(NAMES[0]);
      addChip(NAMES[1]);
      window.setTimeout(() => {
        order.reverse();
        relayout();
      }, 40);
    } else {
      let phase = 0;
      let nextAt = 0;
      const step = (now: number): void => {
        if (now >= nextAt) {
          if (phase < 4) {
            nextAt = now + 640;
            addChip(NAMES[phase % NAMES.length]);
            phase++;
          } else {
            nextAt = now + 900;
            const alive = order.filter((idx) => chips[idx]);
            if (alive.length > 1) {
              const from = 1 + Math.floor(rnd() * (order.length - 1));
              const moved = order.splice(from, 1)[0];
              order.splice(0, 0, moved);
              relayout();
            }
            phase++;
          }
        }
        rafRef.current = requestAnimationFrame(step);
      };
      rafRef.current = requestAnimationFrame(step);
    }

    return () => {
      cancelAnimationFrame(rafRef.current);
      settleTimers.forEach((id) => window.clearTimeout(id));
      zone.removeEventListener("dragover", onOver as EventListener);
      zone.removeEventListener("dragleave", onLeave);
      zone.removeEventListener("drop", onDrop as EventListener);
      input.removeEventListener("change", onChange);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.rq}>
        <p className={styles.hint} id="rqHintReact">{HINT}</p>
        <div
          className={styles.zone}
          ref={zoneRef}
          role="button"
          tabIndex={0}
          aria-describedby="rqHintReact"
          aria-label={ARIA_LABEL}
        >
          <input type="file" multiple className={styles.file} ref={inputRef} aria-label="파일 선택" />
          <svg className={styles.ic} viewBox="0 0 256 256" aria-hidden="true">
            <g fill="currentColor">
              <path d="M208 32v192a16 16 0 0 1-16 16H64a16 16 0 0 1-16-16V32a16 16 0 0 1 16-16h128a16 16 0 0 1 16 16" opacity=".2" />
              <path d="M104 60a12 12 0 1 1-12-12a12 12 0 0 1 12 12m60 12a12 12 0 1 0-12-12a12 12 0 0 0 12 12m-72 44a12 12 0 1 0 12 12a12 12 0 0 0-12-12m72 0a12 12 0 1 0 12 12a12 12 0 0 0-12-12m-72 68a12 12 0 1 0 12 12a12 12 0 0 0-12-12m72 0a12 12 0 1 0 12 12a12 12 0 0 0-12-12" />
            </g>
          </svg>
        </div>
        <ul className={styles.list} ref={listRef} aria-live="polite" />
        <p className={styles.meta}>
          <span className={styles.tag} ref={tagRef} style={{ color }}>done 0/0</span>
          <span className={styles.unit} ref={unitRef}>order</span>
        </p>
      </div>
    </main>
  );
}