01One round trip from loading to done

<main class="stage">
  <div class="ac is-demo">
    <button class="ac__btn" id="ac-btn" type="button" data-state="idle" aria-busy="false">
      <span class="ac__face" data-face="idle">
        <span class="ac__t">Save</span>
      </span>
      <span class="ac__face" data-face="busy">
        <span class="ac__ic ac__ic--spin" aria-hidden="true"><svg viewBox="0 0 256 256" width="20" height="20"><g fill="currentColor"><path d="M224 128a96 96 0 1 1-96-96a96 96 0 0 1 96 96" opacity=".2"/><path d="M136 32v32a8 8 0 0 1-16 0V32a8 8 0 0 1 16 0m88 88h-32a8 8 0 0 0 0 16h32a8 8 0 0 0 0-16m-45.09 47.6a8 8 0 0 0-11.31 11.31l22.62 22.63a8 8 0 0 0 11.32-11.32ZM128 184a8 8 0 0 0-8 8v32a8 8 0 0 0 16 0v-32a8 8 0 0 0-8-8m-50.91-16.4l-22.63 22.62a8 8 0 0 0 11.32 11.32l22.62-22.63a8 8 0 0 0-11.31-11.31M72 128a8 8 0 0 0-8-8H32a8 8 0 0 0 0 16h32a8 8 0 0 0 8-8m-6.22-73.54a8 8 0 0 0-11.32 11.32L77.09 88.4A8 8 0 0 0 88.4 77.09Z"/></g></svg></span>
        <span class="ac__t">Saving</span>
      </span>
      <span class="ac__face" data-face="done">
        <span class="ac__ic" aria-hidden="true"><svg viewBox="0 0 256 256" width="20" height="20"><g fill="currentColor"><path d="M224 128a96 96 0 1 1-96-96a96 96 0 0 1 96 96" opacity=".2"/><path d="M173.66 98.34a8 8 0 0 1 0 11.32l-56 56a8 8 0 0 1-11.32 0l-24-24a8 8 0 0 1 11.32-11.32L112 148.69l50.34-50.35a8 8 0 0 1 11.32 0M232 128A104 104 0 1 1 128 24a104.11 104.11 0 0 1 104 104m-16 0a88 88 0 1 0-88 88a88.1 88.1 0 0 0 88-88"/></g></svg></span>
        <span class="ac__t">Saved</span>
      </span>
    </button>
    <p class="ac__log" role="status" aria-live="polite">
      <span class="ac__word" data-word="idle">Ready</span>
      <span class="ac__word" data-word="busy">Sending</span>
      <span class="ac__word" data-word="done">Done</span>
    </p>
  </div>
</main>

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

$duration: $dur-quick;
$easing: $ease-spring;
$color: $subject-mint;

@include stage($stage-ink);

.ac {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  width: min(280px, 84vw);
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.ac__btn {
  position: relative;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 48px;
  overflow: hidden;
  border: 0;
  border-radius: $r-control;
  background-color: $subject-cream;
  color: $subject-ink;
  cursor: pointer;
  box-shadow: $shadow-raised;
}
.ac__btn:focus-visible { outline: 3px solid $color; outline-offset: 3px; }

.ac__face {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: $sp-2;
  opacity: 0;
}
.ac__ic { display: inline-flex; flex: 0 0 auto; }
.ac__ic svg { display: block; }
.ac__t {
  font-size: 15px;
  line-height: 20px;
  font-weight: 700;
  white-space: nowrap;
}

// 사람이 실제로 누른 경로 — 루프를 껐을 때도 화면이 비지 않게 정적 규칙을 먼저 둔다
.ac:not(.is-demo) .ac__btn[data-state="idle"] .ac__face[data-face="idle"],
.ac:not(.is-demo) .ac__btn[data-state="busy"] .ac__face[data-face="busy"],
.ac:not(.is-demo) .ac__btn[data-state="done"] .ac__face[data-face="done"] { opacity: 1; }
.ac:not(.is-demo) .ac__btn[data-state="busy"] { background-color: $subject-blue; color: $subject-cream; }
.ac:not(.is-demo) .ac__btn[data-state="done"] { background-color: $color; color: $subject-ink; }

.ac__log {
  position: relative;
  margin: 0;
  width: 100%;
  height: 18px;
}
.ac__word {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  text-align: center;
  font-size: 12px;
  line-height: 18px;
  font-weight: 500;
  color: $subject-cream;
  opacity: 0;
}
.ac:not(.is-demo) .ac__btn[data-state="idle"] ~ .ac__log .ac__word[data-word="idle"],
.ac:not(.is-demo) .ac__btn[data-state="busy"] ~ .ac__log .ac__word[data-word="busy"],
.ac:not(.is-demo) .ac__btn[data-state="done"] ~ .ac__log .ac__word[data-word="done"] { opacity: 1; }

// 스피너는 도는 동안 매 프레임 달라진다 — 컷 두 번만으로는 움직인 프레임이 안 찬다
.ac__ic--spin svg {
  animation-name: ac-spin;
  animation-duration: 800ms;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}
@keyframes ac-spin {
  from { transform: rotate(0deg); }
  to   { transform: rotate(360deg); }
}

// ── 자동 루프: idle → busy(20%) → done(60%) → idle(88%). 상태 교체는 한 프레임에 끊는다 ──
.ac.is-demo .ac__face,
.ac.is-demo .ac__word {
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.ac.is-demo .ac__face[data-face="idle"],
.ac.is-demo .ac__word[data-word="idle"] { animation-name: ac-idle; }
.ac.is-demo .ac__face[data-face="busy"],
.ac.is-demo .ac__word[data-word="busy"] { animation-name: ac-busy; }
.ac.is-demo .ac__face[data-face="done"],
.ac.is-demo .ac__word[data-word="done"] { animation-name: ac-done; }

@keyframes ac-idle {
  0%   { opacity: 1; }
  20%  { opacity: 0; }
  88%  { opacity: 1; }
  100% { opacity: 1; }
}
@keyframes ac-busy {
  0%   { opacity: 0; }
  20%  { opacity: 1; }
  60%  { opacity: 0; }
  100% { opacity: 0; }
}
@keyframes ac-done {
  0%   { opacity: 0; }
  60%  { opacity: 1; }
  88%  { opacity: 0; }
  100% { opacity: 0; }
}

// 껍질 색은 컷으로, 눌림 반동은 부드럽게 — 두 애니메이션을 한 요소에 겹쳐 건다
.ac.is-demo .ac__btn {
  animation-name: ac-skin, ac-pop;
  animation-duration: $dur-loop, $dur-loop;
  animation-timing-function: steps(1, end), $easing;
  animation-iteration-count: infinite, infinite;
}
@keyframes ac-skin {
  0%   { background-color: $subject-cream; color: $subject-ink; }
  20%  { background-color: $subject-blue; color: $subject-cream; }
  60%  { background-color: $color; color: $subject-ink; }
  88%  { background-color: $subject-cream; color: $subject-ink; }
  100% { background-color: $subject-cream; color: $subject-ink; }
}

// 완료로 갈리는 순간 버튼이 한 번 눌렸다 펴진다 — 컷만으로는 대표 장면이 밋밋하다
@keyframes ac-pop {
  0%   { transform: scale(1); }
  18%  { transform: scale(1); }
  22%  { transform: scale(.96); }
  30%  { transform: scale(1); }
  58%  { transform: scale(1); }
  63%  { transform: scale(1.04); }
  72%  { transform: scale(1); }
  100% { transform: scale(1); }
}

@media (max-width: 340px) {
  .ac { gap: $sp-2; }
  .ac__btn { height: 44px; }
  .ac__t { font-size: 13px; line-height: 18px; }
}

@media (prefers-reduced-motion: reduce) {
  .ac.is-demo .ac__face,
  .ac.is-demo .ac__word,
  .ac.is-demo .ac__btn,
  .ac__ic--spin svg { animation: none !important; }
  .ac.is-demo .ac__face[data-face="idle"],
  .ac.is-demo .ac__word[data-word="idle"] { opacity: 1; }
}

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);
}

.ac {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  width: min(280px, 84vw);
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.ac__btn {
  position: relative;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 48px;
  overflow: hidden;
  border: 0;
  border-radius: 12px;
  background-color: #fff7e6;
  color: #17141a;
  cursor: pointer;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.ac__btn:focus-visible {
  outline: 3px solid #4cd4a6;
  outline-offset: 3px;
}

.ac__face {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  opacity: 0;
}

.ac__ic {
  display: inline-flex;
  flex: 0 0 auto;
}

.ac__ic svg {
  display: block;
}

.ac__t {
  font-size: 15px;
  line-height: 20px;
  font-weight: 700;
  white-space: nowrap;
}

.ac:not(.is-demo) .ac__btn[data-state=idle] .ac__face[data-face=idle],
.ac:not(.is-demo) .ac__btn[data-state=busy] .ac__face[data-face=busy],
.ac:not(.is-demo) .ac__btn[data-state=done] .ac__face[data-face=done] {
  opacity: 1;
}

.ac:not(.is-demo) .ac__btn[data-state=busy] {
  background-color: #2f6df6;
  color: #fff7e6;
}

.ac:not(.is-demo) .ac__btn[data-state=done] {
  background-color: #4cd4a6;
  color: #17141a;
}

.ac__log {
  position: relative;
  margin: 0;
  width: 100%;
  height: 18px;
}

.ac__word {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  text-align: center;
  font-size: 12px;
  line-height: 18px;
  font-weight: 500;
  color: #fff7e6;
  opacity: 0;
}

.ac:not(.is-demo) .ac__btn[data-state=idle] ~ .ac__log .ac__word[data-word=idle],
.ac:not(.is-demo) .ac__btn[data-state=busy] ~ .ac__log .ac__word[data-word=busy],
.ac:not(.is-demo) .ac__btn[data-state=done] ~ .ac__log .ac__word[data-word=done] {
  opacity: 1;
}

.ac__ic--spin svg {
  animation-name: ac-spin;
  animation-duration: 800ms;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

@keyframes ac-spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}
.ac.is-demo .ac__face,
.ac.is-demo .ac__word {
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.ac.is-demo .ac__face[data-face=idle],
.ac.is-demo .ac__word[data-word=idle] {
  animation-name: ac-idle;
}

.ac.is-demo .ac__face[data-face=busy],
.ac.is-demo .ac__word[data-word=busy] {
  animation-name: ac-busy;
}

.ac.is-demo .ac__face[data-face=done],
.ac.is-demo .ac__word[data-word=done] {
  animation-name: ac-done;
}

@keyframes ac-idle {
  0% {
    opacity: 1;
  }
  20% {
    opacity: 0;
  }
  88% {
    opacity: 1;
  }
  100% {
    opacity: 1;
  }
}
@keyframes ac-busy {
  0% {
    opacity: 0;
  }
  20% {
    opacity: 1;
  }
  60% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes ac-done {
  0% {
    opacity: 0;
  }
  60% {
    opacity: 1;
  }
  88% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
.ac.is-demo .ac__btn {
  animation-name: ac-skin, ac-pop;
  animation-duration: 2s, 2s;
  animation-timing-function: steps(1, end), cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite, infinite;
}

@keyframes ac-skin {
  0% {
    background-color: #fff7e6;
    color: #17141a;
  }
  20% {
    background-color: #2f6df6;
    color: #fff7e6;
  }
  60% {
    background-color: #4cd4a6;
    color: #17141a;
  }
  88% {
    background-color: #fff7e6;
    color: #17141a;
  }
  100% {
    background-color: #fff7e6;
    color: #17141a;
  }
}
@keyframes ac-pop {
  0% {
    transform: scale(1);
  }
  18% {
    transform: scale(1);
  }
  22% {
    transform: scale(0.96);
  }
  30% {
    transform: scale(1);
  }
  58% {
    transform: scale(1);
  }
  63% {
    transform: scale(1.04);
  }
  72% {
    transform: scale(1);
  }
  100% {
    transform: scale(1);
  }
}
@media (max-width: 340px) {
  .ac {
    gap: 8px;
  }
  .ac__btn {
    height: 44px;
  }
  .ac__t {
    font-size: 13px;
    line-height: 18px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ac.is-demo .ac__face,
  .ac.is-demo .ac__word,
  .ac.is-demo .ac__btn,
  .ac__ic--spin svg {
    animation: none !important;
  }
  .ac.is-demo .ac__face[data-face=idle],
  .ac.is-demo .ac__word[data-word=idle] {
    opacity: 1;
  }
}

// 실제 동작: 한 번 누르면 busy → done → idle 로 스스로 돌아온다. 도는 동안 버튼은 잠긴다
var root = document.querySelector('.ac');
var btn = document.getElementById('ac-btn');
var t1 = 0, t2 = 0;
function setState(s) {
  btn.setAttribute('data-state', s);
  btn.setAttribute('aria-busy', String(s === 'busy'));
  btn.disabled = s !== 'idle';
}
btn.addEventListener('click', function () {
  root.classList.remove('is-demo');
  clearTimeout(t1);
  clearTimeout(t2);
  setState('busy');
  t1 = setTimeout(function () { setState('done'); }, 1200);   // 서버가 답한 시점
  t2 = setTimeout(function () { setState('idle'); }, 3200);   // 완료 표시를 2초 보여 주고 원복
});

import { useState, useRef, useEffect } from "react";
import type { CSSProperties } from "react";
import styles from "./AsyncCycleButton.module.scss";

export type AsyncState = "idle" | "busy" | "done";
export type AsyncCycleButtonProps = {
  labels?: Record<AsyncState, string>;
  logs?: Record<AsyncState, string>;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type Timer = ReturnType<typeof setTimeout>;

const BUSY_MS = 1200; // 서버가 답한 시점
const DONE_MS = 2000; // 완료 표시를 2초 보여 주고 원복

const SPINNER = (
  <g fill="currentColor">
    <path d="M224 128a96 96 0 1 1-96-96a96 96 0 0 1 96 96" opacity=".2" />
    <path d="M136 32v32a8 8 0 0 1-16 0V32a8 8 0 0 1 16 0m88 88h-32a8 8 0 0 0 0 16h32a8 8 0 0 0 0-16m-45.09 47.6a8 8 0 0 0-11.31 11.31l22.62 22.63a8 8 0 0 0 11.32-11.32ZM128 184a8 8 0 0 0-8 8v32a8 8 0 0 0 16 0v-32a8 8 0 0 0-8-8m-50.91-16.4l-22.63 22.62a8 8 0 0 0 11.32 11.32l22.62-22.63a8 8 0 0 0-11.31-11.31M72 128a8 8 0 0 0-8-8H32a8 8 0 0 0 0 16h32a8 8 0 0 0 8-8m-6.22-73.54a8 8 0 0 0-11.32 11.32L77.09 88.4A8 8 0 0 0 88.4 77.09Z" />
  </g>
);

const CHECK = (
  <g fill="currentColor">
    <path d="M224 128a96 96 0 1 1-96-96a96 96 0 0 1 96 96" opacity=".2" />
    <path d="M173.66 98.34a8 8 0 0 1 0 11.32l-56 56a8 8 0 0 1-11.32 0l-24-24a8 8 0 0 1 11.32-11.32L112 148.69l50.34-50.35a8 8 0 0 1 11.32 0M232 128A104 104 0 1 1 128 24a104.11 104.11 0 0 1 104 104m-16 0a88 88 0 1 0-88 88a88.1 88.1 0 0 0 88-88" />
  </g>
);

export default function AsyncCycleButton({
  labels = { idle: "Save", busy: "Saving", done: "Saved" },
  logs = { idle: "Ready to press", busy: "Sending now", done: "All done" },
  duration = 220,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#4cd4a6",
}: AsyncCycleButtonProps) {
  const [demo, setDemo] = useState(true);
  const [state, setState] = useState<AsyncState>("idle");
  const t1 = useRef<Timer>(null);
  const t2 = useRef<Timer>(null);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  function clear() {
    if (t1.current !== null) clearTimeout(t1.current);
    if (t2.current !== null) clearTimeout(t2.current);
  }
  useEffect(() => clear, []); // 떠날 때 예약된 타이머를 버린다

  // 한 번 누르면 busy → done → idle 로 스스로 돌아온다. 도는 동안 버튼은 잠긴다
  function run() {
    setDemo(false); // 사람이 눌렀으니 자동 루프를 끈다
    clear();
    setState("busy");
    t1.current = setTimeout(() => setState("done"), BUSY_MS);
    t2.current = setTimeout(() => setState("idle"), BUSY_MS + DONE_MS);
  }

  return (
    <div className={`${styles.ac} ${demo ? styles.isDemo : ""}`} style={vars}>
      <button
        className={styles.btn}
        type="button"
        data-state={state}
        aria-busy={state === "busy"}
        disabled={state !== "idle"}
        onClick={run}
      >
        <span className={styles.face} data-face="idle">
          <span className={styles.txt}>{labels.idle}</span>
        </span>
        <span className={styles.face} data-face="busy">
          <span className={`${styles.ic} ${styles.icSpin}`} aria-hidden="true">
            <svg viewBox="0 0 256 256" width="20" height="20">{SPINNER}</svg>
          </span>
          <span className={styles.txt}>{labels.busy}</span>
        </span>
        <span className={styles.face} data-face="done">
          <span className={styles.ic} aria-hidden="true">
            <svg viewBox="0 0 256 256" width="20" height="20">{CHECK}</svg>
          </span>
          <span className={styles.txt}>{labels.done}</span>
        </span>
      </button>
      <p className={styles.log} role="status" aria-live="polite">
        <span className={styles.word} data-word="idle">{logs.idle}</span>
        <span className={styles.word} data-word="busy">{logs.busy}</span>
        <span className={styles.word} data-word="done">{logs.done}</span>
      </p>
    </div>
  );
}