08Animated list reorder

<main class="stage">
  <div class="pages is-demo">
    <p class="page__tag">RANKING</p>
    <div class="rows">
      <div class="row row--1"><span class="row__rank">1</span><span class="row__name">Price: low to high</span></div>
      <div class="row row--2"><span class="row__rank">2</span><span class="row__name">Highest rated</span></div>
      <div class="row row--3"><span class="row__rank">3</span><span class="row__name">Newest first</span></div>
    </div>
  </div>
</main>

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

// ── 변수 3개. 변형은 이것만 바꾼다 (값은 토큰에서 받는다) ──────
$duration: $dur-base;
$easing: $ease-spring;
$color: $subject-blue-deep;

// ── 데모 무대 ───────────────────────────────
@include stage($stage-paper);

.pages { position: relative; width: min(300px, 88%); height: 150px; border-radius: $r-card; overflow: hidden; box-shadow: $shadow-raised; background: #fff; box-sizing: border-box; padding: clamp(12px, 5vw, 18px); }
.page__tag { margin: 0 0 8px; font-weight: 700; font-size: clamp(9px, 2.6vw, 11px); line-height: 1; font-family: inherit; letter-spacing: .12em; color: $subject-ink; opacity: .72; }
.rows { position: relative; height: 96px; }
.row {
  position: absolute; left: 0; right: 0; height: 28px; border-radius: 8px;
  background: rgba(0, 0, 0, .04); display: flex; align-items: center; gap: 10px;
  padding: 0 12px; box-sizing: border-box; font-weight: 600; font-size: clamp(11px, 3.2vw, 13px); line-height: 1; font-family: inherit; color: $subject-ink;
}
.row__rank { color: $color; font-weight: 700; }
.row--1 { top: 0; }
.row--2 { top: 34px; }
.row--3 { top: 68px; }

// 1위와 2위가 자리를 바꾼다. FLIP 처럼 최종 위치 차이만큼만 translateY 로 옮긴다.
.row--1 { animation: swap-down $dur-loop $easing infinite; }
.row--2 { animation: swap-up $dur-loop $easing infinite; }

@keyframes swap-down {
  0%, 5% { transform: translateY(0); }
  50% { transform: translateY(34px); }
  95%, 100% { transform: translateY(0); }
}
@keyframes swap-up {
  0%, 5% { transform: translateY(0); }
  50% { transform: translateY(-34px); }
  95%, 100% { transform: translateY(0); }
}

// ── 접근성: 움직임 줄이기 설정이면 최종 상태만 고정으로 ────────
@media (prefers-reduced-motion: reduce) {
  .row--1, .row--2 { animation: none !important; transform: translateY(0); }
}

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

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

.pages {
  position: relative;
  width: min(300px, 88%);
  height: 150px;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  background: #fff;
  box-sizing: border-box;
  padding: clamp(12px, 5vw, 18px);
}

.page__tag {
  margin: 0 0 8px;
  font-weight: 700;
  font-size: clamp(9px, 2.6vw, 11px);
  line-height: 1;
  font-family: inherit;
  letter-spacing: 0.12em;
  color: #17141a;
  opacity: 0.72;
}

.rows {
  position: relative;
  height: 96px;
}

.row {
  position: absolute;
  left: 0;
  right: 0;
  height: 28px;
  border-radius: 8px;
  background: rgba(0, 0, 0, 0.04);
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 12px;
  box-sizing: border-box;
  font-weight: 600;
  font-size: clamp(11px, 3.2vw, 13px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}

.row__rank {
  color: #0a4fe8;
  font-weight: 700;
}

.row--1 {
  top: 0;
}

.row--2 {
  top: 34px;
}

.row--3 {
  top: 68px;
}

.row--1 {
  animation: swap-down 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.row--2 {
  animation: swap-up 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes swap-down {
  0%, 5% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(34px);
  }
  95%, 100% {
    transform: translateY(0);
  }
}
@keyframes swap-up {
  0%, 5% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-34px);
  }
  95%, 100% {
    transform: translateY(0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .row--1, .row--2 {
    animation: none !important;
    transform: translateY(0);
  }
}

import type { CSSProperties, ReactNode } from "react";
import styles from "./ListReorderTransition.module.scss";

export type ListReorderTransitionProps = {
  /** "asc": 기본 순서, "swapped": 1·2위가 바뀐 순서 */
  active: "asc" | "swapped";
  row1: ReactNode;
  row2: ReactNode;
  row3: ReactNode;
  /** 이동이 끝나는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
  color?: string;
  className?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function ListReorderTransition({
  active,
  row1,
  row2,
  row3,
  duration = 300,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#0a4fe8",
  className = "",
}: ListReorderTransitionProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={`${styles.pages} ${className}`} style={vars} data-active={active}>
      <div className={styles.rows}>
        <div className={styles.row1}>{row1}</div>
        <div className={styles.row2}>{row2}</div>
        <div className={styles.row3}>{row3}</div>
      </div>
    </div>
  );
}