06Corruption-retry count value — the retry-count value climbs by one and the progress value resets to the start whenever verification fails

<main class="stage">
<div class="dcr is-demo" id="dcr">
  <div class="dcr__head">
    <span class="dcr__state" id="dcrState">Downloading</span>
    <span class="dcr__retry" id="dcrRetry">Retry 0</span>
  </div>
  <div class="dcr__track"><div class="dcr__fill" id="dcrFill"></div></div>
  <button class="dcr__btn" id="dcrBtn" type="button">Retry now</button>
</div>
</main>

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

// 계산 겹: 재시도 대기 = 기저값 × 배수^재시도횟수(지수 백오프) — index.html backoffMs() 참조
@include stage($stage-yellow);

.dcr {
  width: 100%;
  max-width: 230px;
  display: grid;
  gap: $sp-3;
}

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

.dcr--bad .dcr__state { color: $error; }
.dcr--ok .dcr__state { color: $subject-ink; }

.dcr__retry { font-variant-numeric: tabular-nums; color: rgba($subject-ink, .68); }

.dcr__track {
  width: 100%;
  height: $sp-3;
  border-radius: $r-pill;
  background: rgba($subject-ink, .14);
  overflow: hidden;
}

.dcr__fill {
  height: 100%;
  width: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  border-radius: $r-pill;
  background: $subject-ink;
  transition: transform $dur-instant linear;
}

.dcr--bad .dcr__fill { background: $error; }
.dcr--ok .dcr__fill { background: $subject-mint; }

.dcr__btn {
  width: 100%;
  border: 0;
  border-radius: $r-control;
  padding: $sp-2 $sp-4;
  background: $subject-ink;
  color: $subject-cream;
  font: 700 12px/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) {
  .dcr { max-width: 195px; }
}

@media (prefers-reduced-motion: reduce) {
  .dcr__fill, .dcr__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: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.dcr {
  width: 100%;
  max-width: 230px;
  display: grid;
  gap: 12px;
}

.dcr__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #17141a;
}

.dcr--bad .dcr__state {
  color: #c2361a;
}

.dcr--ok .dcr__state {
  color: #17141a;
}

.dcr__retry {
  font-variant-numeric: tabular-nums;
  color: rgba(23, 20, 26, 0.68);
}

.dcr__track {
  width: 100%;
  height: 12px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.14);
  overflow: hidden;
}

.dcr__fill {
  height: 100%;
  width: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  border-radius: 999px;
  background: #17141a;
  transition: transform 140ms linear;
}

.dcr--bad .dcr__fill {
  background: #c2361a;
}

.dcr--ok .dcr__fill {
  background: #4cd4a6;
}

.dcr__btn {
  width: 100%;
  border: 0;
  border-radius: 12px;
  padding: 8px 16px;
  background: #17141a;
  color: #fff7e6;
  font: 700 12px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.dcr__btn:active {
  transform: scale(0.96);
}

@media (max-width: 340px) {
  .dcr {
    max-width: 195px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .dcr__fill, .dcr__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('dcr');
  var state = document.getElementById('dcrState');
  var retryEl = document.getElementById('dcrRetry');
  var fill = document.getElementById('dcrFill');
  var btn = document.getElementById('dcrBtn');

  // 시드 고정: 회차별 검증 결과(참=검증 통과). 0·1회차는 Corrupted, 2회차부터 통과
  var VERIFY_SEED = [false, false, true, true, true];
  // 상수: 틱 간격 · 기저 대기(ms) · 지수 배수 — 재시도할 때마다 대기 시간이 늘어난다
  var TICK_MS = 90;
  var BASE_BACKOFF_MS = 260;
  var BACKOFF_MULT = 2;
  var MAX_PCT = 100;

  var pct = 0;
  var retry = 0;
  var timer = null;
  var btnDisabled = false;

  // 계산 겹: Retry 대기 = 기저값 × 배수^재시도횟수(지수 백오프) — 매 실패마다 대기가 길어진다
  function backoffMs() {
    return BASE_BACKOFF_MS * Math.pow(BACKOFF_MULT, Math.min(retry, 4));
  }

  function paint() {
    fill.style.transform = 'scaleX(' + (pct / MAX_PCT).toFixed(3) + ')';
    retryEl.textContent = 'Retry ' + retry;
  }

  function verify() {
    var ok = VERIFY_SEED[retry % VERIFY_SEED.length];
    if (ok) {
      state.textContent = 'Done';
      root.classList.add('dcr--ok');
      setTimeout(reset, 900);
    } else {
      state.textContent = 'Corrupted';
      root.classList.add('dcr--bad');
      retry++;
      pct = 0;
      paint();
      var wait = backoffMs();
      timer = setTimeout(function () {
        root.classList.remove('dcr--bad');
        state.textContent = 'Downloading';
        download();
      }, wait);
    }
  }

  function download() {
    if (pct >= MAX_PCT) { verify(); return; }
    pct = Math.min(MAX_PCT, pct + 9);
    paint();
    timer = setTimeout(download, TICK_MS);
  }

  function reset() {
    root.classList.remove('dcr--ok', 'dcr--bad');
    pct = 0; retry = 0; state.textContent = 'Downloading';
    paint();
    download();
  }

  download();

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    if (timer) clearTimeout(timer);
    reset();
  });
})();

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

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

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

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

    // 시드 고정: 회차별 검증 결과(참=검증 통과). 0·1회차는 손상, 2회차부터 통과
    const VERIFY_SEED = [false, false, true, true, true];
    const TICK_MS = 90;
    const BASE_BACKOFF_MS = 260;
    const BACKOFF_MULT = 2;
    const MAX_PCT = 100;

    let pct = 0;
    let retry = 0;
    let timer = 0;
    let stopped = false;

    // 계산 겹: 재시도 대기 = 기저값 × 배수^재시도횟수(지수 백오프) — 매 실패마다 대기가 길어진다
    function backoffMs() {
      return BASE_BACKOFF_MS * Math.pow(BACKOFF_MULT, Math.min(retry, 4));
    }

    function paint() {
      fill!.style.transform = "scaleX(" + (pct / MAX_PCT).toFixed(3) + ")";
      retryEl!.textContent = "재시도 " + retry;
    }

    function verify() {
      const ok = VERIFY_SEED[retry % VERIFY_SEED.length];
      if (ok) {
        state!.textContent = "완료";
        root!.classList.add(styles["dcr--ok"]);
        timer = window.setTimeout(reset, 900);
      } else {
        state!.textContent = "손상";
        root!.classList.add(styles["dcr--bad"]);
        retry++;
        pct = 0;
        paint();
        const wait = backoffMs();
        timer = window.setTimeout(() => {
          root!.classList.remove(styles["dcr--bad"]);
          state!.textContent = "받는 중";
          download();
        }, wait);
      }
    }

    function download() {
      if (stopped) return;
      if (pct >= MAX_PCT) { verify(); return; }
      pct = Math.min(MAX_PCT, pct + 9);
      paint();
      timer = window.setTimeout(download, TICK_MS);
    }

    function reset() {
      root!.classList.remove(styles["dcr--ok"], styles["dcr--bad"]);
      pct = 0; retry = 0; state!.textContent = "받는 중";
      paint();
      download();
    }

    download();

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      window.clearTimeout(timer);
      reset();
    }
    btn.addEventListener("click", onClick);

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

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.dcr} ${styles["is-demo"]}`}>
      <div className={styles.head}>
        <span className={styles.state}>받는 중</span>
        <span className={styles.retry}>재시도 0</span>
      </div>
      <div className={styles.track}><div className={styles.fill} /></div>
      <button className={styles.btn} type="button">지금 재시도</button>
    </div>
  );
}