02Circular percent ring computed from its own circumference

<main class="stage">
<div class="rp is-demo" id="rpRoot" role="group" tabindex="0" aria-label="File upload progress ring">
  <div class="rp__ringwrap">
    <svg class="rp__svg" viewBox="0 0 120 120" width="92" height="92" aria-hidden="true">
      <circle class="rp__track" cx="60" cy="60" r="52"></circle>
      <circle class="rp__prog" id="rpProg" cx="60" cy="60" r="52"></circle>
    </svg>
    <span class="rp__pct" id="rpPct" aria-hidden="true"><b class="rp__n"></b><i>%</i></span>
  </div>
  <div class="rp__bar">
    <span class="rp__label">Uploading</span>
    <span class="rp__meta">stroke-dashoffset · getBoundingClientRect</span>
  </div>
</div>
</main>

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

// 원형 퍼센트 링(02) — 링의 stroke-dashoffset 과 라벨 숫자는 같은 --p 값에서 나온다(두 갈래 keyframes 지만
// 같은 스케줄). --circ 는 JS 가 실측한 반지름으로 딱 한 번 계산해 넣는 상수 — 애니메이션 대상이 아니다.

@property --p {
  syntax: "<number>";
  inherits: false;
  initial-value: 0;
}
@property --n {
  syntax: "<integer>";
  inherits: false;
  initial-value: 0;
}

@include stage($stage-yellow);

$rp-track: $subject-ink;
$rp-arc:   $subject-blue-deep;

$duration: $dur-loop;
$easing: $ease-out;
$color: $rp-arc;

.rp {
  display: flex; flex-direction: column; align-items: center;
  gap: $sp-4;
  width: 100%; height: 100%; min-height: 164px;
  justify-content: center;
}
.rp:focus-visible { outline: 2px solid $rp-arc; outline-offset: 3px; border-radius: $r-control; }

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

.rp__svg { transform: rotate(-90deg); }
.rp__track {
  fill: none;
  stroke: rgba($rp-track, .16);
  stroke-width: 9;
}
.rp__prog {
  fill: none;
  stroke: $rp-arc;
  stroke-width: 9;
  stroke-linecap: round;
  --circ: 0;
  --p: 0;
  stroke-dasharray: var(--circ);
  stroke-dashoffset: calc(var(--circ) * (1 - var(--p) / 100));
}

.rp__pct {
  position: absolute;
  display: flex; align-items: baseline; gap: 0;
  font-weight: 700; font-size: 22px; line-height: 1;
  color: $rp-track;
  --n: 0;
}
.rp__pct i { font-weight: 600; font-size: 12px; font-style: normal; opacity: .7; }
.rp__n { counter-reset: rpn var(--n); }
.rp__n::before { content: counter(rpn); }

.rp__bar {
  display: flex; flex-direction: column; align-items: center; gap: $sp-1;
}
.rp__label {
  font-weight: 600; font-size: 11px; line-height: 1.3;
  color: rgba($rp-track, .82);
}
.rp__meta {
  font-weight: 500; font-size: 10px; line-height: 1.3;
  color: rgba($rp-track, .62);
}

// ── 데모 루프 — 0→100 을 채우고, 화면에서 사라진 순간에만 0으로 되감아 눈에 튀는 점프가 없다 ──
@keyframes rpArc {
  0%   { --p: 0; }
  70%  { --p: 100; }
  90%  { --p: 100; }
  92%  { --p: 0; }
  100% { --p: 0; }
}
@keyframes rpCount {
  0%   { --n: 0; }
  70%  { --n: 100; }
  90%  { --n: 100; }
  92%  { --n: 0; }
  100% { --n: 0; }
}
@keyframes rpFade {
  0%   { opacity: 1; }
  84%  { opacity: 1; }
  90%  { opacity: 0; }
  94%  { opacity: 0; }
  100% { opacity: 1; }
}

.is-demo .rp__prog {
  animation-name: rpArc;
  animation-duration: $duration;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
.is-demo .rp__pct {
  animation-name: rpCount;
  animation-duration: $duration;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}
.is-demo .rp__ringwrap {
  animation-name: rpFade;
  animation-duration: $duration;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}

@media (max-width: 340px) {
  .rp__svg { width: 78px; height: 78px; }
  .rp__pct { font-size: 18px; }
}

@media (prefers-reduced-motion: reduce) {
  .is-demo .rp__prog, .is-demo .rp__pct, .is-demo .rp__ringwrap { animation: none !important; }
  .is-demo .rp__prog { --p: 62 !important; }
  .is-demo .rp__pct { --n: 62 !important; }
}

@property --p {
  syntax: "<number>";
  inherits: false;
  initial-value: 0;
}
@property --n {
  syntax: "<integer>";
  inherits: false;
  initial-value: 0;
}
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);
}

.rp {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  width: 100%;
  height: 100%;
  min-height: 164px;
  justify-content: center;
}

.rp:focus-visible {
  outline: 2px solid #0a4fe8;
  outline-offset: 3px;
  border-radius: 12px;
}

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

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

.rp__track {
  fill: none;
  stroke: rgba(23, 20, 26, 0.16);
  stroke-width: 9;
}

.rp__prog {
  fill: none;
  stroke: #0a4fe8;
  stroke-width: 9;
  stroke-linecap: round;
  --circ: 0;
  --p: 0;
  stroke-dasharray: var(--circ);
  stroke-dashoffset: calc(var(--circ) * (1 - var(--p) / 100));
}

.rp__pct {
  position: absolute;
  display: flex;
  align-items: baseline;
  gap: 0;
  font-weight: 700;
  font-size: 22px;
  line-height: 1;
  color: #17141a;
  --n: 0;
}

.rp__pct i {
  font-weight: 600;
  font-size: 12px;
  font-style: normal;
  opacity: 0.7;
}

.rp__n {
  counter-reset: rpn var(--n);
}

.rp__n::before {
  content: counter(rpn);
}

.rp__bar {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.rp__label {
  font-weight: 600;
  font-size: 11px;
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.82);
}

.rp__meta {
  font-weight: 500;
  font-size: 10px;
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.62);
}

@keyframes rpArc {
  0% {
    --p: 0;
  }
  70% {
    --p: 100;
  }
  90% {
    --p: 100;
  }
  92% {
    --p: 0;
  }
  100% {
    --p: 0;
  }
}
@keyframes rpCount {
  0% {
    --n: 0;
  }
  70% {
    --n: 100;
  }
  90% {
    --n: 100;
  }
  92% {
    --n: 0;
  }
  100% {
    --n: 0;
  }
}
@keyframes rpFade {
  0% {
    opacity: 1;
  }
  84% {
    opacity: 1;
  }
  90% {
    opacity: 0;
  }
  94% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}
.is-demo .rp__prog {
  animation-name: rpArc;
  animation-duration: 2s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}

.is-demo .rp__pct {
  animation-name: rpCount;
  animation-duration: 2s;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

.is-demo .rp__ringwrap {
  animation-name: rpFade;
  animation-duration: 2s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}

@media (max-width: 340px) {
  .rp__svg {
    width: 78px;
    height: 78px;
  }
  .rp__pct {
    font-size: 18px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .is-demo .rp__prog, .is-demo .rp__pct, .is-demo .rp__ringwrap {
    animation: none !important;
  }
  .is-demo .rp__prog {
    --p: 62 !important;
  }
  .is-demo .rp__pct {
    --n: 62 !important;
  }
}

// 원형 퍼센트 링 — 반지름을 실측(getBoundingClientRect)해 둘레(2πr)를 구하고
// stroke-dasharray 에 그 값을 그대로 넣는다. 진행률은 stroke-dashoffset 을
// 둘레에서 되감는 비율로 계산하므로 숫자 라벨과 링은 항상 같은 값을 가리킨다.
// 실제 전송 속도는 매 틱 일정하지 않다 — 시드 난수로 목표치를 흔들고
// 화면 값은 목표를 향해 관성으로 lerp 되어 뚝뚝 끊기지 않는다.
(function () {
  var SEED = 0x9e77a1;
  function mulberry32(a) {
    return function () {
      a |= 0; a = (a + 0x6D2B79F5) | 0;
      var t = Math.imul(a ^ (a >>> 15), 1 | a);
      t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
      return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
    };
  }
  var rand = mulberry32(SEED);

  var root = document.getElementById('rpRoot');
  var prog = document.getElementById('rpProg');
  var pct  = document.getElementById('rpPct');
  if (!root || !prog || !pct) return;

  var r = prog.r.baseVal.value;
  var box = prog.getBoundingClientRect();
  var measuredR = box.width > 0 ? box.width / 2 : r;
  var circ = 2 * Math.PI * measuredR;
  prog.style.setProperty('--circ', String(circ));

  var target = 0, shown = 0, raf = null;
  function paint() {
    shown += (target - shown) * 0.18;
    if (Math.abs(target - shown) < 0.05) shown = target;
    prog.style.setProperty('--p', shown.toFixed(2));
    pct.style.setProperty('--n', Math.round(shown));
    if (shown < 100) raf = requestAnimationFrame(paint);
  }
  function tick() {
    if (root.classList.contains('is-demo')) return;
    target = Math.min(100, target + 3 + rand() * 9);
    if (target >= 100) clearInterval(timer);
  }
  var timer = null;
  function live() {
    if (!root.classList.contains('is-demo')) return;
    root.classList.remove('is-demo');
    timer = setInterval(tick, 220);
    raf = requestAnimationFrame(paint);
  }
  ['pointerdown', 'focusin'].forEach(function (ev) { root.addEventListener(ev, live); });
})();

// UploadProgressRingPercent — vanilla 판(run/329/demo/02-upload-progress-ring-percent/index.html) 의 React 포트.
// 반지름을 실측(getBoundingClientRect)해 둘레(2πr)를 구하고 stroke-dasharray 에 그 값을 그대로 넣는다.
// 진행률은 stroke-dashoffset 을 둘레에서 되감는 비율로 계산하므로 숫자 라벨과 링은 항상 같은 값을 가리킨다.
// 실제 전송 속도는 매 틱 일정하지 않다 — 시드 난수(mulberry32)로 목표치를 흔들고
// 화면 값은 목표를 향해 관성으로 lerp 되어 뚝뚝 끊기지 않는다.
import { useEffect, useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./UploadProgressRingPercent.module.scss";

export type UploadProgressRingPercentProps = {
  duration?: string;
  easing?: string;
  color?: string;
  seed?: number;   // mulberry32 시드 — 흔들림 패턴을 고정한다
  step?: number;   // 매 틱 기본 증가분(퍼센트 포인트)
  jitter?: number; // 매 틱 랜덤 증가분 상한
  tickMs?: number; // 진행 틱 주기(ms)
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type Box<T> = { current: T };

const LABEL = "업로드 중";
const META = "stroke-dashoffset · getBoundingClientRect";
const SEED = 0x9e77a1;

function mulberry32(a: number): () => number {
  return function () {
    a |= 0; a = (a + 0x6D2B79F5) | 0;
    const t = Math.imul(a ^ (a >>> 15), 1 | a);
    const u = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((u ^ (u >>> 14)) >>> 0) / 4294967296;
  };
}

export default function UploadProgressRingPercent({
  duration = "2s",
  easing = "ease-out",
  color = "#0a4fe8",
  seed = SEED,
  step = 3,
  jitter = 9,
  tickMs = 220
}: UploadProgressRingPercentProps) {
  const [demo, setDemo] = useState(true);
  const progRef = useRef<SVGCircleElement | null>(null);
  const pctRef = useRef<HTMLSpanElement | null>(null);
  const targetRef = useRef(0) as Box<number>;
  const shownRef = useRef(0) as Box<number>;
  const rafRef = useRef(0) as Box<number>;
  const timerRef = useRef(0) as Box<number>;
  const randRef = useRef<(() => number) | null>(null);
  const vars: Vars = { "--duration": duration, "--easing": easing, "--color": color };

  useEffect(() => {
    return () => {
      window.clearInterval(timerRef.current);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  function live(): void {
    if (!demo) return;
    setDemo(false);
    const prog = progRef.current;
    const pct = pctRef.current;
    if (!prog) return;
    const rand = mulberry32(seed);
    randRef.current = rand;
    // 둘레 — 반지름을 실측해 한 번만 계산하는 상수(vanilla 판과 같은 절차)
    const r = prog.r.baseVal.value;
    const box = prog.getBoundingClientRect();
    const measuredR = box.width > 0 ? box.width / 2 : r;
    const circ = 2 * Math.PI * measuredR;
    prog.style.setProperty("--circ", String(circ));

    const stepFn = (): void => {
      targetRef.current = Math.min(100, targetRef.current + step + rand() * jitter);
      const target = targetRef.current;
      if (target >= 100) window.clearInterval(timerRef.current);
      const frame = (): void => {
        shownRef.current += (target - shownRef.current) * 0.18;
        if (Math.abs(target - shownRef.current) < 0.05) shownRef.current = target;
        prog.style.setProperty("--p", shownRef.current.toFixed(2));
        if (pct) pct.style.setProperty("--n", String(Math.round(shownRef.current)));
        if (shownRef.current < 100) rafRef.current = requestAnimationFrame(frame);
      };
      frame();
    };
    timerRef.current = window.setInterval(stepFn, tickMs);
    stepFn();
  }

  const rootCls = demo ? `${styles.rp} ${styles.isDemo}` : styles.rp;

  return (
    <main className={styles.stage}>
      <div
        className={rootCls}
        style={vars}
        role="group"
        tabIndex={0}
        aria-label="파일 업로드 진행률 링"
        onPointerDown={live}
        onFocus={live}
      >
        <div className={styles.ringwrap}>
          <svg className={styles.svg} viewBox="0 0 120 120" width="92" height="92" aria-hidden="true">
            <circle className={styles.track} cx="60" cy="60" r="52"></circle>
            <circle className={styles.prog} cx="60" cy="60" r="52" ref={progRef}></circle>
          </svg>
          <span className={styles.pct} ref={pctRef} aria-hidden="true"><b className={styles.n}></b><i>%</i></span>
        </div>
        <div className={styles.bar}>
          <span className={styles.label}>{LABEL}</span>
          <span className={styles.meta}>{META}</span>
        </div>
      </div>
    </main>
  );
}