02Sliding knob

<main class="stage">
  <div class="panel">
    <div class="panel__face panel__face--light">
      <p class="panel__title">Notifications</p>
      <p class="panel__line"></p>
    </div>
    <div class="panel__face panel__face--dark">
      <p class="panel__title">Notifications</p>
      <p class="panel__line"></p>
    </div>
    <span class="track">
      <span class="track__bg track__bg--light"></span>
      <span class="track__bg track__bg--dark"></span>
      <span class="knob"></span>
    </span>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-enter;
$easing: $ease-out;
$color: $subject-blue;

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

.panel {
  position: relative; overflow: hidden;
  width: clamp(200px, 70vw, 260px); height: clamp(120px, 42vw, 150px);
  border-radius: $r-card; box-shadow: $shadow-raised;
}
.panel__face {
  position: absolute; inset: 0; box-sizing: border-box;
  padding: clamp(12px, 5vw, 18px); text-align: left;
}
.panel__face--light {
  background: $subject-cream; color: $subject-ink;
  opacity: 1; animation: face-light $dur-loop $easing infinite;
}
.panel__face--dark {
  background: $stage-ink; color: $subject-cream;
  opacity: 0; animation: face-dark $dur-loop $easing infinite;
}
.panel__title { margin: 0 0 6px; font-weight: 700; font-size: clamp(12px, 3.6vw, 15px); line-height: 1.3; font-family: inherit; }
.panel__line { margin: 0; width: 55%; height: 8px; border-radius: 4px; background: currentColor; opacity: .25; }

.track {
  position: absolute; top: clamp(8px, 3vw, 12px); right: clamp(8px, 3vw, 12px);
  display: block; width: 44px; height: 24px; border-radius: $r-pill; overflow: hidden;
}
.track__bg { position: absolute; inset: 0; }
.track__bg--light { background: rgba(255, 255, 255, .5); opacity: 1; animation: face-light $dur-loop $easing infinite; }
.track__bg--dark  { background: $subject-ink; opacity: 0; animation: face-dark $dur-loop $easing infinite; }
.knob {
  position: absolute; top: 3px; left: 3px; width: 18px; height: 18px; border-radius: 50%;
  background: $color; box-shadow: $shadow-press;
  transform: translateX(0); animation: knob-slide $dur-loop $easing infinite;
}

// 0~15% 라이트 유지 · 15~40% 전환 · 40~60% 다크 유지 · 60~85% 전환 · 85~100% 라이트로 되돌아감
@keyframes face-light { 0%, 15% { opacity: 1; } 40%, 60% { opacity: 0; } 85%, 100% { opacity: 1; } }
@keyframes face-dark  { 0%, 15% { opacity: 0; } 40%, 60% { opacity: 1; } 85%, 100% { opacity: 0; } }
@keyframes knob-slide {
  0%, 15%  { transform: translateX(0); }
  40%, 60% { transform: translateX(20px); }
  85%, 100% { transform: translateX(0); }
}

// ── 접근성: 움직임 줄이기 설정이면 라이트 상태로 고정 ──────────
@media (prefers-reduced-motion: reduce) {
  .panel__face--light, .panel__face--dark, .track__bg--light, .track__bg--dark, .knob { animation: none !important; }
}

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);
}

.panel {
  position: relative;
  overflow: hidden;
  width: clamp(200px, 70vw, 260px);
  height: clamp(120px, 42vw, 150px);
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.panel__face {
  position: absolute;
  inset: 0;
  box-sizing: border-box;
  padding: clamp(12px, 5vw, 18px);
  text-align: left;
}

.panel__face--light {
  background: #fff7e6;
  color: #17141a;
  opacity: 1;
  animation: face-light 2s ease-out infinite;
}

.panel__face--dark {
  background: #17141a;
  color: #fff7e6;
  opacity: 0;
  animation: face-dark 2s ease-out infinite;
}

.panel__title {
  margin: 0 0 6px;
  font-weight: 700;
  font-size: clamp(12px, 3.6vw, 15px);
  line-height: 1.3;
  font-family: inherit;
}

.panel__line {
  margin: 0;
  width: 55%;
  height: 8px;
  border-radius: 4px;
  background: currentColor;
  opacity: 0.25;
}

.track {
  position: absolute;
  top: clamp(8px, 3vw, 12px);
  right: clamp(8px, 3vw, 12px);
  display: block;
  width: 44px;
  height: 24px;
  border-radius: 999px;
  overflow: hidden;
}

.track__bg {
  position: absolute;
  inset: 0;
}

.track__bg--light {
  background: rgba(255, 255, 255, 0.5);
  opacity: 1;
  animation: face-light 2s ease-out infinite;
}

.track__bg--dark {
  background: #17141a;
  opacity: 0;
  animation: face-dark 2s ease-out infinite;
}

.knob {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: #2f6df6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  transform: translateX(0);
  animation: knob-slide 2s ease-out infinite;
}

@keyframes face-light {
  0%, 15% {
    opacity: 1;
  }
  40%, 60% {
    opacity: 0;
  }
  85%, 100% {
    opacity: 1;
  }
}
@keyframes face-dark {
  0%, 15% {
    opacity: 0;
  }
  40%, 60% {
    opacity: 1;
  }
  85%, 100% {
    opacity: 0;
  }
}
@keyframes knob-slide {
  0%, 15% {
    transform: translateX(0);
  }
  40%, 60% {
    transform: translateX(20px);
  }
  85%, 100% {
    transform: translateX(0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .panel__face--light, .panel__face--dark, .track__bg--light, .track__bg--dark, .knob {
    animation: none !important;
  }
}

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

export type SlideKnobToggleProps = {
  dark: boolean;
  onToggle?: () => void;
  /** 노브가 미끄러지는 시간 (기본 600ms) */
  duration?: number;
  easing?: string;
  color?: string;
  className?: string;
};

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

export default function SlideKnobToggle({
  dark,
  onToggle,
  duration = 600,
  easing = "ease-out",
  color = "#2f6df6",
  className = "",
}: SlideKnobToggleProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <button
      type="button"
      className={`${styles.track} ${className}`}
      style={vars}
      data-dark={dark}
      aria-label="다크모드 전환"
      onClick={onToggle}
    >
      <span className={styles.knob} />
    </button>
  );
}