03Threshold commit — a trigger that switches to a committed state once the pulled distance value passes a threshold

<main class="stage">
<div class="prtc is-demo" id="prtc">
  <div class="prtc__phone" id="prtcPhone">
    <div class="prtc__zone">
      <span class="prtc__disc" id="prtcDisc"></span>
    </div>
    <div class="prtc__list" id="prtcList">
      <div class="prtc__row"></div>
      <div class="prtc__row"></div>
      <div class="prtc__row"></div>
    </div>
  </div>
  <span class="prtc__hint" id="prtcHint">Pull down</span>
</div>
</main>

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

// 계산 겹(히스테리시스 setCandidate())은 JS 에 있다 — 여기는 정적 배치만.
@include stage($stage-paper);

.prtc {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
}

.prtc__phone {
  position: relative;
  width: 220px;
  height: 168px;
  overflow: hidden;
  border-radius: $r-card;
  background: $subject-cream;
  touch-action: none;
  cursor: grab;
}

.prtc__zone {
  position: relative;
  height: 56px;
  display: grid;
  place-items: center;
}

.prtc__disc {
  width: 28px;
  height: 28px;
  border-radius: $r-pill;
  background: rgba($subject-ink, .22);
  transition: background $dur-quick $ease-out;

  &--ready { background: $subject-blue-deep; }
  &--spin { animation: prtcSpin .6s linear infinite; }
}

@keyframes prtcSpin {
  from { transform: rotate(0deg) scale(1); }
  to { transform: rotate(360deg) scale(1); }
}

.prtc__list {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
  padding: $sp-3 $sp-4;
}

.prtc__row {
  height: 20px;
  border-radius: $r-sm;
  background: $stage-paper;
}

.prtc__hint {
  color: rgba($subject-ink, .72);
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .prtc__phone { width: 176px; height: 132px; }
  .prtc__zone { height: 44px; }
  .prtc__disc { width: 22px; height: 22px; }
  .prtc__list { padding: $sp-2 $sp-3; gap: $sp-1; }
  .prtc__row { height: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  .prtc__disc, .prtc__list { transition: none !important; animation: none !important; }
}

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);
}

.prtc {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.prtc__phone {
  position: relative;
  width: 220px;
  height: 168px;
  overflow: hidden;
  border-radius: 16px;
  background: #fff7e6;
  touch-action: none;
  cursor: grab;
}

.prtc__zone {
  position: relative;
  height: 56px;
  display: grid;
  place-items: center;
}

.prtc__disc {
  width: 28px;
  height: 28px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.22);
  transition: background 220ms ease-out;
}
.prtc__disc--ready {
  background: #0a4fe8;
}
.prtc__disc--spin {
  animation: prtcSpin 0.6s linear infinite;
}

@keyframes prtcSpin {
  from {
    transform: rotate(0deg) scale(1);
  }
  to {
    transform: rotate(360deg) scale(1);
  }
}
.prtc__list {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px 16px;
}

.prtc__row {
  height: 20px;
  border-radius: 8px;
  background: #ffffff;
}

.prtc__hint {
  color: rgba(23, 20, 26, 0.72);
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .prtc__phone {
    width: 176px;
    height: 132px;
  }
  .prtc__zone {
    height: 44px;
  }
  .prtc__disc {
    width: 22px;
    height: 22px;
  }
  .prtc__list {
    padding: 8px 12px;
    gap: 4px;
  }
  .prtc__row {
    height: 16px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .prtc__disc, .prtc__list {
    transition: none !important;
    animation: none !important;
  }
}

(function () {
  var phone = document.getElementById('prtcPhone');
  var disc = document.getElementById('prtcDisc');
  var list = document.getElementById('prtcList');
  var hint = document.getElementById('prtcHint');
  var root = document.getElementById('prtc');

  // 계산 겹: 확정 여부(committed candidate)는 raw 하나의 부등호가 아니라 두 문턱의 히스테리시스로 정한다.
  // ON(100px) 을 넘으면 true 로, 다시 OFF(70px) 아래로 내려가야만 false 로 — 경계 근처에서 깜빡이지 않는다.
  var ON = 100, OFF = 70, MAX = 160;
  var candidate = false, state = 'idle'; // idle -> dragging -> committing -> idle

  function setCandidate(raw) {
    if (!candidate && raw >= ON) { candidate = true; }
    else if (candidate && raw < OFF) { candidate = false; }
  }

  function apply(raw) {
    setCandidate(raw);
    var pull = Math.min(raw, MAX) * 0.3;
    disc.style.transform = 'translateY(' + pull.toFixed(1) + 'px) scale(' + (0.7 + 0.3 * Math.min(1, raw / ON)).toFixed(2) + ')';
    disc.classList.toggle('prtc__disc--ready', candidate);
    list.style.transform = 'translateY(' + pull.toFixed(1) + 'px)';
    hint.textContent = candidate ? 'Release to refresh' : (raw > 4 ? 'Pull more (' + Math.round(raw) + '/' + ON + 'px)' : 'Pull down');
  }

  function commit() {
    state = 'committing';
    hint.textContent = 'Refreshing';
    disc.classList.add('prtc__disc--spin');
    setTimeout(function () {
      disc.classList.remove('prtc__disc--spin', 'prtc__disc--ready');
      candidate = false; state = 'idle';
      hint.textContent = 'Pull down';
      apply(0);
    }, 620);
  }

  var dragging = false, startY = 0, startRaw = 0, raw = 0, target = 0, raf = null;
  function settle() {
    raw += (target - raw) * 0.3;
    if (Math.abs(target - raw) < 0.3) { raw = target; }
    apply(raw);
    if (raw !== target) { raf = requestAnimationFrame(settle); } else { raf = null; }
  }
  function goTo(v) { target = v; if (raf === null) { raf = requestAnimationFrame(settle); } }

  function onDown(y) {
    if (state !== 'idle') { return; }
    dragging = true; state = 'dragging'; startY = y; startRaw = raw;
    if (raf) { cancelAnimationFrame(raf); raf = null; }
  }
  function onMove(y) {
    if (!dragging) { return; }
    raw = Math.max(0, Math.min(MAX, startRaw + (y - startY)));
    apply(raw);
  }
  function onUp() {
    if (!dragging) { return; }
    dragging = false;
    if (candidate) { commit(); } else { state = 'idle'; goTo(0); }
  }

  function wireReal() {
    phone.addEventListener('pointerdown', function (e) { root.classList.remove('is-demo'); stopAutoplay(); onDown(e.clientY); });
    window.addEventListener('pointermove', function (e) { onMove(e.clientY); });
    window.addEventListener('pointerup', onUp);
  }
  phone.style.touchAction = 'none';
  wireReal();
  apply(0);

  // 자동 루프: raw 를 단계적으로 MAX 까지 올려 같은 setCandidate()·commit() 경로를 탄다.
  var autoRaw = 0, autoTimer = null;
  function autoTick() {
    if (state !== 'idle' && state !== 'dragging') { return; }
    state = 'dragging';
    autoRaw += 28;
    if (autoRaw >= MAX) {
      raw = MAX; apply(raw); autoRaw = 0;
      if (candidate) { commit(); } else { state = 'idle'; goTo(0); }
      return;
    }
    raw = autoRaw; apply(raw);
  }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  if (!reduce) { autoTimer = setInterval(autoTick, 170); }
})();

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

export type PullRefreshThresholdCommitProps = {
  color?: string;
};

export default function PullRefreshThresholdCommit({
  color = "#0a4fe8",
}: PullRefreshThresholdCommitProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const phone = root.querySelector<HTMLDivElement>(`.${styles.phone}`);
    const disc = root.querySelector<HTMLSpanElement>(`.${styles.disc}`);
    const list = root.querySelector<HTMLDivElement>(`.${styles.list}`);
    const hint = root.querySelector<HTMLSpanElement>(`.${styles.hint}`);
    if (!phone || !disc || !list || !hint) return;

    // 계산 겹: 확정 여부(committed candidate)는 raw 하나의 부등호가 아니라 두 문턱의 히스테리시스로 정한다.
    // ON(100px) 을 넘으면 true 로, 다시 OFF(70px) 아래로 내려가야만 false 로 — 경계 근처에서 깜빡이지 않는다.
    const ON = 100, OFF = 70, MAX = 160;
    let candidate = false;
    let state: "idle" | "dragging" | "committing" = "idle";
    const readyClass = styles["disc--ready"];
    const spinClass = styles["disc--spin"];

    function setCandidate(raw: number) {
      if (!candidate && raw >= ON) { candidate = true; }
      else if (candidate && raw < OFF) { candidate = false; }
    }

    function apply(raw: number) {
      setCandidate(raw);
      const pull = Math.min(raw, MAX) * 0.3;
      disc!.style.transform = "translateY(" + pull.toFixed(1) + "px) scale(" + (0.7 + 0.3 * Math.min(1, raw / ON)).toFixed(2) + ")";
      disc!.classList.toggle(readyClass, candidate);
      list!.style.transform = "translateY(" + pull.toFixed(1) + "px)";
      hint!.textContent = candidate ? "놓으면 새로고침" : (raw > 4 ? "더 당기세요 (" + Math.round(raw) + "/" + ON + "px)" : "아래로 당기세요");
    }

    let commitTimer: number | null = null;
    function commit() {
      state = "committing";
      hint!.textContent = "새로고침 중";
      disc!.classList.add(spinClass);
      commitTimer = window.setTimeout(() => {
        disc!.classList.remove(spinClass, readyClass);
        candidate = false; state = "idle";
        hint!.textContent = "아래로 당기세요";
        apply(0);
      }, 620);
    }

    let dragging = false, startY = 0, startRaw = 0, raw = 0, target = 0, raf: number | null = null;
    function settle() {
      raw += (target - raw) * 0.3;
      if (Math.abs(target - raw) < 0.3) { raw = target; }
      apply(raw);
      raf = raw !== target ? requestAnimationFrame(settle) : null;
    }
    function goTo(v: number) { target = v; if (raf === null) { raf = requestAnimationFrame(settle); } }

    function onDown(y: number) {
      if (state !== "idle") return;
      dragging = true; state = "dragging"; startY = y; startRaw = raw;
      if (raf !== null) { cancelAnimationFrame(raf); raf = null; }
    }
    function onMove(y: number) {
      if (!dragging) return;
      raw = Math.max(0, Math.min(MAX, startRaw + (y - startY)));
      apply(raw);
    }
    function onUp() {
      if (!dragging) return;
      dragging = false;
      if (candidate) { commit(); } else { state = "idle"; goTo(0); }
    }

    function onPointerDown(e: PointerEvent) { stopAutoplay(); onDown(e.clientY); }
    function onPointerMove(e: PointerEvent) { onMove(e.clientY); }
    phone.addEventListener("pointerdown", onPointerDown);
    window.addEventListener("pointermove", onPointerMove);
    window.addEventListener("pointerup", onUp);
    apply(0);

    let autoRaw = 0, autoTimer: number | null = null;
    function autoTick() {
      if (state !== "idle" && state !== "dragging") return;
      state = "dragging";
      autoRaw += 28;
      if (autoRaw >= MAX) {
        raw = MAX; apply(raw); autoRaw = 0;
        if (candidate) { commit(); } else { state = "idle"; goTo(0); }
        return;
      }
      raw = autoRaw; apply(raw);
    }
    function stopAutoplay() {
      if (autoTimer !== null) { window.clearInterval(autoTimer); autoTimer = null; }
      if (commitTimer !== null) { window.clearTimeout(commitTimer); }
    }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoTimer = window.setInterval(autoTick, 170); }

    return () => {
      stopAutoplay();
      if (raf !== null) { cancelAnimationFrame(raf); }
      phone.removeEventListener("pointerdown", onPointerDown);
      window.removeEventListener("pointermove", onPointerMove);
      window.removeEventListener("pointerup", onUp);
    };
  }, []);

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.prtc}>
        <div className={styles.phone}>
          <div className={styles.zone}>
            <span className={styles.disc} style={{ "--accent": color } as any} />
          </div>
          <div className={styles.list}>
            <div className={styles.row} />
            <div className={styles.row} />
          </div>
        </div>
        <span className={styles.hint}>아래로 당기세요</span>
      </div>
    </div>
  );
}