04Offline-queue count — the pending-save count value climbs while disconnected and counts back down to zero the instant the connection returns

<main class="stage">
<div class="soq is-demo" id="soq">
  <div class="soq__row">
    <span class="soq__label" id="soqLabel">Offline</span>
    <span class="soq__count" id="soqCount">0 pending</span>
  </div>
  <div class="soq__track"><div class="soq__fill" id="soqFill"></div></div>
  <button class="soq__btn" id="soqBtn" type="button">Toggle connection</button>
</div>
</main>

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

// 계산 겹: 막대 채움 값 = 대기 건수 ÷ 최대 건수(scaleX 산술) — index.html 참조
@include stage($stage-ink);

.soq {
  width: 100%;
  max-width: 260px;
  display: grid;
  justify-items: center;
  gap: $sp-3;
}

.soq__row {
  width: 100%;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-cream;
}

.soq__count { font-variant-numeric: tabular-nums; color: rgba($subject-cream, .8); }

.soq--online .soq__label { color: $subject-mint; }

.soq__track {
  width: 100%;
  height: $sp-2;
  border-radius: $r-pill;
  background: rgba($subject-cream, .16);
  overflow: hidden;
}

.soq__fill {
  height: 100%;
  width: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  border-radius: $r-pill;
  background: $subject-blue-light;
  transition: transform $dur-quick $ease-out, background $dur-base $ease-out;
}

.soq--online .soq__fill { background: $subject-mint; }

.soq__btn {
  border: 0;
  border-radius: $r-control;
  padding: $sp-2 $sp-4;
  background: $subject-cream;
  color: $stage-ink;
  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) {
  .soq { max-width: 200px; }
}

@media (prefers-reduced-motion: reduce) {
  .soq__fill { transition: none; }
  .soq__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: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.soq {
  width: 100%;
  max-width: 260px;
  display: grid;
  justify-items: center;
  gap: 12px;
}

.soq__row {
  width: 100%;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #fff7e6;
}

.soq__count {
  font-variant-numeric: tabular-nums;
  color: rgba(255, 247, 230, 0.8);
}

.soq--online .soq__label {
  color: #4cd4a6;
}

.soq__track {
  width: 100%;
  height: 8px;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.16);
  overflow: hidden;
}

.soq__fill {
  height: 100%;
  width: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  border-radius: 999px;
  background: #5b8cf8;
  transition: transform 220ms ease-out, background 300ms ease-out;
}

.soq--online .soq__fill {
  background: #4cd4a6;
}

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

@media (max-width: 340px) {
  .soq {
    max-width: 200px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .soq__fill {
    transition: none;
  }
  .soq__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('soq');
  var btn = document.getElementById('soqBtn');
  var label = document.getElementById('soqLabel');
  var countEl = document.getElementById('soqCount');
  var fill = document.getElementById('soqFill');

  // 상수: Idle 칸 최대 값 · 쌓이는 간격(가속 ms) · 줄어드는 간격(가속 ms)
  var MAX_QUEUE = 6;
  var ADD_MS = 260;
  var DRAIN_MS = 150;

  var online = false;
  var count = 0;
  var timer = null;

  // 계산 겹: 막대 채움 값 = Idle 건수 ÷ 최대 건수 — scaleX 산술
  function paint() {
    countEl.textContent = count + 'queued';
    fill.style.transform = 'scaleX(' + (count / MAX_QUEUE).toFixed(3) + ')';
    label.textContent = online ? 'Online' : 'Offline';
    root.classList.toggle('soq--online', online);
  }

  function tick() {
    if (!online) {
      count = Math.min(MAX_QUEUE, count + 1);
      paint();
      if (count >= MAX_QUEUE) { online = true; paint(); timer = setTimeout(tick, DRAIN_MS); return; }
      timer = setTimeout(tick, ADD_MS);
    } else {
      count = Math.max(0, count - 1);
      paint();
      if (count <= 0) { timer = setTimeout(function () { online = false; paint(); timer = setTimeout(tick, ADD_MS); }, 500); return; }
      timer = setTimeout(tick, DRAIN_MS);
    }
  }
  timer = setTimeout(tick, ADD_MS);
  paint();

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    if (timer) clearTimeout(timer);
    online = !online;
    paint();
    timer = setTimeout(tick, online ? DRAIN_MS : ADD_MS);
  });
})();

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

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

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

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const label = root.querySelector(`.${styles.label}`) as HTMLElement | null;
    const countEl = root.querySelector(`.${styles.count}`) as HTMLElement | null;
    const fill = root.querySelector(`.${styles.fill}`) as HTMLElement | null;
    const btn = root.querySelector(`.${styles.btn}`) as HTMLElement | null;
    if (!label || !countEl || !fill || !btn) return;

    // 상수: 대기 칸 최대 값 · 쌓이는 간격(가속 ms) · 줄어드는 간격(가속 ms)
    const MAX_QUEUE = 6;
    const ADD_MS = 260;
    const DRAIN_MS = 150;

    let online = false;
    let count = 0;
    let timer = 0;
    let stopped = false;

    // 계산 겹: 막대 채움 값 = 대기 건수 ÷ 최대 건수 — scaleX 산술
    function paint() {
      countEl!.textContent = count + "건 대기";
      fill!.style.transform = "scaleX(" + (count / MAX_QUEUE).toFixed(3) + ")";
      label!.textContent = online ? "온라인" : "오프라인";
      root!.classList.toggle(styles["soq--online"], online);
    }

    function tick() {
      if (stopped) return;
      if (!online) {
        count = Math.min(MAX_QUEUE, count + 1);
        paint();
        if (count >= MAX_QUEUE) { online = true; paint(); timer = window.setTimeout(tick, DRAIN_MS); return; }
        timer = window.setTimeout(tick, ADD_MS);
      } else {
        count = Math.max(0, count - 1);
        paint();
        if (count <= 0) {
          timer = window.setTimeout(() => { online = false; paint(); timer = window.setTimeout(tick, ADD_MS); }, 500);
          return;
        }
        timer = window.setTimeout(tick, DRAIN_MS);
      }
    }
    timer = window.setTimeout(tick, ADD_MS);
    paint();

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      window.clearTimeout(timer);
      online = !online;
      paint();
      timer = window.setTimeout(tick, online ? DRAIN_MS : ADD_MS);
    }
    btn.addEventListener("click", onClick);

    return () => {
      stopped = true;
      window.clearTimeout(timer);
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.soq} ${styles["is-demo"]}`}>
      <div className={styles.row}>
        <span className={styles.label}>오프라인</span>
        <span className={styles.count}>0건 대기</span>
      </div>
      <div className={styles.track}><div className={styles.fill} /></div>
      <button className={styles.btn} type="button">연결 전환</button>
    </div>
  );
}