04대기열 순서 값 재배치 — 아직 시작하지 않은 항목들의 순서 값이 사용자가 정한 차례로 바뀌는 방식

<main class="stage">
<div class="dqr is-demo" id="dqr">
  <div class="dqr__item" data-order="0" id="dqrItem0">대기 A</div>
  <div class="dqr__item" data-order="1" id="dqrItem1">대기 B</div>
  <div class="dqr__item" data-order="2" id="dqrItem2">대기 C</div>
  <div class="dqr__item" data-order="3" id="dqrItem3">대기 D</div>
</div>
</main>

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

// 계산 겹: 순서 값 → 목표 위치, 실제 위치는 매 프레임 남은 거리의 18%씩 다가가는 보간(lerp) — index.html tickLerp() 참조
@include stage($stage-ink);

.dqr {
  position: relative;
  width: 100%;
  max-width: 220px;
  height: 160px; // 4 × ROW_H(40px)
}

.dqr__item {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 32px;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  padding: 0 $sp-3;
  border-radius: $r-sm;
  background: $subject-blue-light;
  color: $stage-ink;
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: grab;
  touch-action: none;
  user-select: none;
  will-change: transform;
}

.dqr__item--drag {
  cursor: grabbing;
  background: $subject-cream;
  box-shadow: $shadow-raised;
  z-index: 2;
}

@media (max-width: 340px) {
  .dqr { max-width: 190px; }
  .dqr__item { height: 30px; font-size: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  .dqr__item { transition: none; }
}

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);
}

.dqr {
  position: relative;
  width: 100%;
  max-width: 220px;
  height: 160px;
}

.dqr__item {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 32px;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  padding: 0 12px;
  border-radius: 8px;
  background: #5b8cf8;
  color: #17141a;
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: grab;
  touch-action: none;
  user-select: none;
  will-change: transform;
}

.dqr__item--drag {
  cursor: grabbing;
  background: #fff7e6;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  z-index: 2;
}

@media (max-width: 340px) {
  .dqr {
    max-width: 190px;
  }
  .dqr__item {
    height: 30px;
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .dqr__item {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('dqr');
  var items = [document.getElementById('dqrItem0'), document.getElementById('dqrItem1'), document.getElementById('dqrItem2'), document.getElementById('dqrItem3')];

  // 상수: 항목 높이(px, gap 포함) · 순서→위치 보간 속도(1프레임당 남은 거리의 비율)
  var ROW_H = 40;
  var LERP = 0.18;
  var AUTO_SWAP_MS = 900;

  var order = [0, 1, 2, 3]; // order[i] = i번째 칸에 있는 항목 index
  var y = [0, 1, 2, 3].map(function (i) { return i * ROW_H; }); // 각 항목의 실제(보간 중) y
  var dragging = -1;
  var dragStartY = 0, dragStartTop = 0;

  function targetY(itemIdx) {
    var slot = order.indexOf(itemIdx);
    return slot * ROW_H;
  }

  // 계산 겹: 순서 값이 바뀌면 목표 위치로 즉시 점프하지 않고 매 프레임 남은 거리의 LERP 비율만큼 다가간다
  function tickLerp() {
    for (var i = 0; i < items.length; i++) {
      if (i === dragging) continue;
      var t = targetY(i);
      y[i] += (t - y[i]) * LERP;
      items[i].style.transform = 'translateY(' + y[i].toFixed(2) + 'px)';
    }
    requestAnimationFrame(tickLerp);
  }
  requestAnimationFrame(tickLerp);

  function swap(a, b) {
    var sa = order.indexOf(a), sb = order.indexOf(b);
    order[sa] = b; order[sb] = a;
  }

  // 자동 루프: 대기 중인 항목의 순서 값을 주기적으로 맞바꾼다
  var autoSeq = [[0, 2], [1, 3], [0, 1], [2, 3], [0, 3]];
  var autoI = 0;
  function autoStep() {
    if (root.classList.contains('is-demo')) {
      var pair = autoSeq[autoI % autoSeq.length];
      swap(pair[0], pair[1]);
      autoI++;
    }
    setTimeout(autoStep, AUTO_SWAP_MS);
  }
  setTimeout(autoStep, AUTO_SWAP_MS);

  // 실사용자 드래그: pointerdown/move/up 으로 순서 값을 직접 바꾼다
  items.forEach(function (el, idx) {
    el.addEventListener('pointerdown', function (e) {
      root.classList.remove('is-demo');
      dragging = idx;
      dragStartY = e.clientY;
      dragStartTop = y[idx];
      el.setPointerCapture(e.pointerId);
      el.classList.add('dqr__item--drag');
    });
    el.addEventListener('pointermove', function (e) {
      if (dragging !== idx) return;
      var ny = dragStartTop + (e.clientY - dragStartY);
      y[idx] = ny;
      el.style.transform = 'translateY(' + ny.toFixed(2) + 'px)';
      var slot = Math.max(0, Math.min(items.length - 1, Math.round(ny / ROW_H)));
      var curSlot = order.indexOf(idx);
      if (slot !== curSlot) {
        var other = order[slot];
        order[curSlot] = other;
        order[slot] = idx;
      }
    });
    function end(e) {
      if (dragging !== idx) return;
      dragging = -1;
      el.classList.remove('dqr__item--drag');
    }
    el.addEventListener('pointerup', end);
    el.addEventListener('pointercancel', end);
  });
})();

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

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

export default function DownloadManagerQueueReorder() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement | null>;

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const items = [0, 1, 2, 3].map((i) => root.querySelector(`.${styles["item" + i]}`) as HTMLElement | null);
    if (items.some((el) => !el)) return;

    // 상수: 항목 높이(px, gap 포함) · 순서→위치 보간 속도(1프레임당 남은 거리의 비율)
    const ROW_H = 40;
    const LERP = 0.18;
    const AUTO_SWAP_MS = 900;

    const order = [0, 1, 2, 3];
    const y = [0, 1, 2, 3].map((i) => i * ROW_H);
    let dragging = -1;
    let dragStartY = 0, dragStartTop = 0;
    let stopped = false;
    let rafId = 0;
    let autoTimer = 0;

    function targetY(itemIdx: number) {
      const slot = order.indexOf(itemIdx);
      return slot * ROW_H;
    }

    // 계산 겹: 순서 값이 바뀌면 목표 위치로 즉시 점프하지 않고 매 프레임 남은 거리의 LERP 비율만큼 다가간다
    function tickLerp() {
      if (stopped) return;
      for (let i = 0; i < items.length; i++) {
        if (i === dragging) continue;
        const t = targetY(i);
        y[i] += (t - y[i]) * LERP;
        items[i]!.style.transform = "translateY(" + y[i].toFixed(2) + "px)";
      }
      rafId = requestAnimationFrame(tickLerp);
    }
    rafId = requestAnimationFrame(tickLerp);

    function swap(a: number, b: number) {
      const sa = order.indexOf(a), sb = order.indexOf(b);
      order[sa] = b; order[sb] = a;
    }

    const autoSeq = [[0, 2], [1, 3], [0, 1], [2, 3], [0, 3]];
    let autoI = 0;
    function autoStep() {
      if (stopped) return;
      if (root!.classList.contains(styles["is-demo"])) {
        const pair = autoSeq[autoI % autoSeq.length];
        swap(pair[0], pair[1]);
        autoI++;
      }
      autoTimer = window.setTimeout(autoStep, AUTO_SWAP_MS);
    }
    autoTimer = window.setTimeout(autoStep, AUTO_SWAP_MS);

    const cleanups: Array<() => void> = [];
    items.forEach((el, idx) => {
      function onDown(e: PointerEvent) {
        root!.classList.remove(styles["is-demo"]);
        dragging = idx;
        dragStartY = e.clientY;
        dragStartTop = y[idx];
        el!.setPointerCapture(e.pointerId);
        el!.classList.add(styles["item--drag"]);
      }
      function onMove(e: PointerEvent) {
        if (dragging !== idx) return;
        const ny = dragStartTop + (e.clientY - dragStartY);
        y[idx] = ny;
        el!.style.transform = "translateY(" + ny.toFixed(2) + "px)";
        const slot = Math.max(0, Math.min(items.length - 1, Math.round(ny / ROW_H)));
        const curSlot = order.indexOf(idx);
        if (slot !== curSlot) {
          const other = order[slot];
          order[curSlot] = other;
          order[slot] = idx;
        }
      }
      function onEnd() {
        if (dragging !== idx) return;
        dragging = -1;
        el!.classList.remove(styles["item--drag"]);
      }
      el!.addEventListener("pointerdown", onDown);
      el!.addEventListener("pointermove", onMove);
      el!.addEventListener("pointerup", onEnd);
      el!.addEventListener("pointercancel", onEnd);
      cleanups.push(() => {
        el!.removeEventListener("pointerdown", onDown);
        el!.removeEventListener("pointermove", onMove);
        el!.removeEventListener("pointerup", onEnd);
        el!.removeEventListener("pointercancel", onEnd);
      });
    });

    return () => {
      stopped = true;
      cancelAnimationFrame(rafId);
      window.clearTimeout(autoTimer);
      cleanups.forEach((fn) => fn());
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.dqr} ${styles["is-demo"]}`}>
      <div className={`${styles.item} ${styles.item0}`}>대기 A</div>
      <div className={`${styles.item} ${styles.item1}`}>대기 B</div>
      <div className={`${styles.item} ${styles.item2}`}>대기 C</div>
      <div className={`${styles.item} ${styles.item3}`}>대기 D</div>
    </div>
  );
}