08Next-autosave countdown — the time-remaining value counts down toward zero in a ring

<main class="stage">
<div class="sac is-demo" id="sac">
  <div class="sac__ringwrap">
    <svg class="sac__ring" viewBox="0 0 100 100" width="120" height="120">
      <circle class="sac__track" cx="50" cy="50" r="40"></circle>
      <circle class="sac__prog" id="sacProg" cx="50" cy="50" r="40"></circle>
    </svg>
    <div class="sac__mid">
      <span class="sac__num" id="sacNum">10</span>
      <span class="sac__unit">sec until save</span>
    </div>
  </div>
  <button class="sac__btn" id="sacBtn" type="button">Save now</button>
</div>
</main>

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

// 계산 겹: stroke-dashoffset = 둘레×(1 − 남은초/전체초) — index.html 참조
@include stage($stage-paper);

.sac {
  display: grid;
  justify-items: center;
  gap: $sp-4;
}

.sac__ringwrap {
  position: relative;
  display: grid;
  place-items: center;
}

.sac__ring { transform: rotate(-90deg); }

.sac__track {
  fill: none;
  stroke: rgba($stage-ink, .12);
  stroke-width: 8;
}

.sac__prog {
  fill: none;
  stroke: $subject-blue-deep;
  stroke-width: 8;
  stroke-linecap: round;
  transition: stroke $dur-base $ease-out;
}

.sac--saving .sac__prog { stroke: $subject-mint; }

.sac__mid {
  position: absolute;
  display: grid;
  justify-items: center;
}

.sac__num {
  font: 800 30px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $stage-ink;
  font-variant-numeric: tabular-nums;
}

.sac__unit {
  font: 500 10px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: rgba($stage-ink, .6);
}

.sac__btn {
  border: 0;
  border-radius: $r-control;
  padding: $sp-2 $sp-4;
  background: $stage-ink;
  color: $subject-cream;
  font: 700 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform $dur-instant $ease-out;

  &:active { transform: scale(.96); }
}

@media (max-width: 340px) {
  .sac__ring { width: 92px; height: 92px; }
  .sac__num { font-size: 24px; }
}

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

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);
}

.sac {
  display: grid;
  justify-items: center;
  gap: 16px;
}

.sac__ringwrap {
  position: relative;
  display: grid;
  place-items: center;
}

.sac__ring {
  transform: rotate(-90deg);
}

.sac__track {
  fill: none;
  stroke: rgba(23, 20, 26, 0.12);
  stroke-width: 8;
}

.sac__prog {
  fill: none;
  stroke: #0a4fe8;
  stroke-width: 8;
  stroke-linecap: round;
  transition: stroke 300ms ease-out;
}

.sac--saving .sac__prog {
  stroke: #4cd4a6;
}

.sac__mid {
  position: absolute;
  display: grid;
  justify-items: center;
}

.sac__num {
  font: 800 30px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #17141a;
  font-variant-numeric: tabular-nums;
}

.sac__unit {
  font: 500 10px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: rgba(23, 20, 26, 0.6);
}

.sac__btn {
  border: 0;
  border-radius: 12px;
  padding: 8px 16px;
  background: #17141a;
  color: #fff7e6;
  font: 700 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.sac__btn:active {
  transform: scale(0.96);
}

@media (max-width: 340px) {
  .sac__ring {
    width: 92px;
    height: 92px;
  }
  .sac__num {
    font-size: 24px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .sac__prog {
    transition: none;
  }
  .sac__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('sac');
  var btn = document.getElementById('sacBtn');
  var numEl = document.getElementById('sacNum');
  var prog = document.getElementById('sacProg');

  // 상수: 다음 저장까지 초 · 링 반지름(SVG 좌표) · 데모 안 "1초"의 실제 ms(가속)
  var CYCLE_SEC = 10;
  var R = 40;
  var DEMO_TICK_MS = 130;
  var CIRC = 2 * Math.PI * R;
  prog.style.strokeDasharray = CIRC.toFixed(2);

  var remaining = CYCLE_SEC;
  var timerId = null;

  // 계산 겹: 링 오프셋 = 둘레 × (1 − 남은초/전체초) — stroke-dashoffset 산술
  function paint() {
    numEl.textContent = String(remaining);
    var offset = CIRC * (1 - remaining / CYCLE_SEC);
    prog.style.strokeDashoffset = offset.toFixed(2);
    root.classList.toggle('sac--saving', remaining <= 0);
  }

  function start() {
    remaining = CYCLE_SEC;
    root.classList.remove('sac--saving');
    paint();
    if (timerId) clearInterval(timerId);
    timerId = setInterval(function () {
      remaining -= 1;
      if (remaining <= 0) {
        remaining = 0;
        paint();
        clearInterval(timerId);
        timerId = setTimeout(start, 500);
        return;
      }
      paint();
    }, DEMO_TICK_MS);
  }
  start();

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    if (timerId) { clearInterval(timerId); clearTimeout(timerId); }
    remaining = 0;
    paint();
    timerId = setTimeout(start, 500);
  });
})();

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

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

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

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const numEl = root.querySelector(`.${styles.num}`) as HTMLElement | null;
    const prog = root.querySelector(`.${styles.prog}`) as SVGCircleElement | null;
    const btn = root.querySelector(`.${styles.btn}`) as HTMLElement | null;
    if (!numEl || !prog || !btn) return;

    // 상수: 다음 저장까지 초 · 링 반지름(SVG 좌표) · 데모 안 "1초"의 실제 ms(가속)
    const CYCLE_SEC = 10;
    const R = 40;
    const DEMO_TICK_MS = 130;
    const CIRC = 2 * Math.PI * R;
    prog.style.strokeDasharray = CIRC.toFixed(2);

    let remaining = CYCLE_SEC;
    let timerId = 0;

    // 계산 겹: 링 오프셋 = 둘레 × (1 − 남은초/전체초) — stroke-dashoffset 산술
    function paint() {
      numEl!.textContent = String(remaining);
      const offset = CIRC * (1 - remaining / CYCLE_SEC);
      prog!.style.strokeDashoffset = offset.toFixed(2);
      root!.classList.toggle(styles["sac--saving"], remaining <= 0);
    }

    function start() {
      remaining = CYCLE_SEC;
      root!.classList.remove(styles["sac--saving"]);
      paint();
      window.clearInterval(timerId);
      timerId = window.setInterval(() => {
        remaining -= 1;
        if (remaining <= 0) {
          remaining = 0;
          paint();
          window.clearInterval(timerId);
          timerId = window.setTimeout(start, 500);
          return;
        }
        paint();
      }, DEMO_TICK_MS);
    }
    start();

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      window.clearInterval(timerId);
      window.clearTimeout(timerId);
      remaining = 0;
      paint();
      timerId = window.setTimeout(start, 500);
    }
    btn.addEventListener("click", onClick);

    return () => {
      window.clearInterval(timerId);
      window.clearTimeout(timerId);
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.sac} ${styles["is-demo"]}`}>
      <div className={styles.ringwrap}>
        <svg className={styles.ring} viewBox="0 0 100 100" width="120" height="120">
          <circle className={styles.track} cx="50" cy="50" r="40" />
          <circle className={styles.prog} cx="50" cy="50" r="40" />
        </svg>
        <div className={styles.mid}>
          <span className={styles.num}>10</span>
          <span className={styles.unit}>초 후 저장</span>
        </div>
      </div>
      <button className={styles.btn} type="button">지금 저장</button>
    </div>
  );
}