05Vertical snap

<main class="stage">
  <div class="vs is-demo">
    <div class="vs__viewport">
      <div class="vs__track">
        <section class="vs__slide vs__slide--1"><span class="vs__cap">01</span></section>
        <section class="vs__slide vs__slide--2"><span class="vs__cap">02</span></section>
        <section class="vs__slide vs__slide--3"><span class="vs__cap">03</span></section>
        <section class="vs__slide vs__slide--1" aria-hidden="true"><span class="vs__cap">01</span></section>
      </div>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-base;
$easing: $ease-spring;
$color: $stage-orange;

@include stage($stage-ink);

.vs { width: min(180px, 50vw); height: 150px; border-radius: $r-card; overflow: hidden; }

// ── 실제 동작: 가로가 아니라 세로로 overflow-y:auto + scroll-snap-type: y (0줄 JS) ──
.vs__viewport {
  height: 100%;
  overflow-y: auto;
  scroll-snap-type: y mandatory;
  scrollbar-width: none;
  &::-webkit-scrollbar { display: none; }
}
.vs__track { display: flex; flex-direction: column; height: max-content; }
.vs__slide {
  flex: 0 0 150px;
  width: 100%;
  scroll-snap-align: start;
  display: grid; place-items: end start;
  box-sizing: border-box;
}
.vs__slide--1 { background: linear-gradient(160deg, $subject-blue, #d6ddeb); }
.vs__slide--2 { background: linear-gradient(160deg, $color, #ebdbd6); }
.vs__slide--3 { background: linear-gradient(160deg, #c2ae82, $stage-yellow); }
.vs__cap {
  margin: $sp-3;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .85);
  color: $subject-ink;
  font-weight: 700;
  font-size: 13px;
  line-height: 1;
  font-family: inherit;
}

// ── 데모 루프: 클릭·드래그 전까지 한 칸씩 스스로 아래로 넘어간다 ──
// 트랙 끝에는 1번의 복제본(aria-hidden)이 한 장 더 — 그곳까지 정상 속도로 가고
// 100%→0% 점프는 복제본이 1번과 같아 안 보인다 (끝→처음 텔레포트 금지)
.vs.is-demo .vs__track { animation: vs-loop $dur-loop $easing infinite; }
@keyframes vs-loop {
  0%, 8%    { transform: translateY(0px); }
  31%, 39%  { transform: translateY(-150px); }
  62%, 70%  { transform: translateY(-300px); }
  92%, 100% { transform: translateY(-450px); }
}

// ── 접근성 ──────────────────────────────────────────
@media (prefers-reduced-motion: reduce) {
  .vs.is-demo .vs__track { animation: none !important; }
  .vs__viewport { scroll-behavior: auto; }
}

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);
}

.vs {
  width: min(180px, 50vw);
  height: 150px;
  border-radius: 16px;
  overflow: hidden;
}

.vs__viewport {
  height: 100%;
  overflow-y: auto;
  scroll-snap-type: y mandatory;
  scrollbar-width: none;
}
.vs__viewport::-webkit-scrollbar {
  display: none;
}

.vs__track {
  display: flex;
  flex-direction: column;
  height: max-content;
}

.vs__slide {
  flex: 0 0 150px;
  width: 100%;
  scroll-snap-align: start;
  display: grid;
  place-items: end start;
  box-sizing: border-box;
}

.vs__slide--1 {
  background: linear-gradient(160deg, #2f6df6, #d6ddeb);
}

.vs__slide--2 {
  background: linear-gradient(160deg, #ff4d1f, #ebdbd6);
}

.vs__slide--3 {
  background: linear-gradient(160deg, #c2ae82, #ffd23f);
}

.vs__cap {
  margin: 12px;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #17141a;
  font-weight: 700;
  font-size: 13px;
  line-height: 1;
  font-family: inherit;
}

.vs.is-demo .vs__track {
  animation: vs-loop 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes vs-loop {
  0%, 8% {
    transform: translateY(0px);
  }
  31%, 39% {
    transform: translateY(-150px);
  }
  62%, 70% {
    transform: translateY(-300px);
  }
  92%, 100% {
    transform: translateY(-450px);
  }
}
@media (prefers-reduced-motion: reduce) {
  .vs.is-demo .vs__track {
    animation: none !important;
  }
  .vs__viewport {
    scroll-behavior: auto;
  }
}

// 실제 동작은 overflow-y:auto + scroll-snap-type: y 만으로 끝난다(0줄).
// 이 3줄은 미리보기 자동 재생만 멈춘다.
document.querySelector('.vs__viewport').addEventListener('pointerdown', function () {
  document.querySelector('.vs').classList.remove('is-demo');
});

import type { CSSProperties } from "react";
import styles from "./VerticalSnap.module.scss";

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

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

export default function VerticalSnap({ duration = 300, easing = "cubic-bezier(.2,.8,.2,1)", color = "#ff4d1f" }: VerticalSnapProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={styles.vs} style={vars}>
      {/* 가로가 아니라 세로로 overflow-y:auto + scroll-snap-type: y 만으로 끝난다 — 0줄 JS */}
      <div className={styles.viewport}>
        <div className={styles.track}>
          {[1, 2, 3].map((n) => (
            <div key={n} className={`${styles.slide} ${styles["slide" + n]}`} />
          ))}
        </div>
      </div>
    </div>
  );
}