06Ratchet tick — an indicator that briefly snaps in position each time the pulled distance value passes a tick value

<main class="stage">
<div class="prtk is-demo" id="prtk">
  <div class="prtk__panel">
    <div class="prtk__track" id="prtkTrack">
      <span class="prtk__tick" style="bottom:22px"></span>
      <span class="prtk__tick" style="bottom:44px"></span>
      <span class="prtk__tick" style="bottom:66px"></span>
      <span class="prtk__tick" style="bottom:88px"></span>
      <span class="prtk__marker" id="prtkMarker"></span>
    </div>
    <div class="prtk__phone" id="prtkPhone">
      <div class="prtk__list" id="prtkList">
        <div class="prtk__row"></div>
        <div class="prtk__row"></div>
      </div>
    </div>
  </div>
  <span class="prtk__hint" id="prtkHint">Pull down</span>
</div>
</main>

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

// 계산 겹(감쇠 진동 burst)은 JS 에 있다 — 여기는 정적 배치만.
@include stage($stage-yellow);

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

.prtk__panel {
  display: flex;
  align-items: flex-end;
  gap: $sp-4;
  padding: $sp-4;
  border-radius: $r-card;
  background: $stage-paper;
}

.prtk__track {
  position: relative;
  width: 20px;
  height: 110px;
  border-radius: $r-xs;
  background: $subject-cream;
}

.prtk__tick {
  position: absolute;
  left: -3px;
  right: -3px;
  height: 2px;
  background: rgba($subject-ink, .3);
}

.prtk__marker {
  position: absolute;
  left: 2px;
  right: 2px;
  bottom: 2px;
  height: 12px;
  border-radius: $r-xs;
  background: $subject-blue-deep;
}

.prtk__phone {
  position: relative;
  width: 156px;
  height: 108px;
  overflow: hidden;
  border-radius: $r-sm;
  background: $subject-cream;
  touch-action: none;
  cursor: grab;
}

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

.prtk__row {
  height: 18px;
  border-radius: $r-xs;
  background: $stage-paper;
}

.prtk__hint {
  color: $subject-ink;
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .prtk__panel { padding: $sp-3; gap: $sp-2; }
  .prtk__track { height: 88px; }
  .prtk__phone { width: 128px; height: 88px; }
}

@media (prefers-reduced-motion: reduce) {
  .prtk__marker, .prtk__list { transition: none !important; }
}

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);
}

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

.prtk__panel {
  display: flex;
  align-items: flex-end;
  gap: 16px;
  padding: 16px;
  border-radius: 16px;
  background: #ffffff;
}

.prtk__track {
  position: relative;
  width: 20px;
  height: 110px;
  border-radius: 4px;
  background: #fff7e6;
}

.prtk__tick {
  position: absolute;
  left: -3px;
  right: -3px;
  height: 2px;
  background: rgba(23, 20, 26, 0.3);
}

.prtk__marker {
  position: absolute;
  left: 2px;
  right: 2px;
  bottom: 2px;
  height: 12px;
  border-radius: 4px;
  background: #0a4fe8;
}

.prtk__phone {
  position: relative;
  width: 156px;
  height: 108px;
  overflow: hidden;
  border-radius: 8px;
  background: #fff7e6;
  touch-action: none;
  cursor: grab;
}

.prtk__list {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px;
}

.prtk__row {
  height: 18px;
  border-radius: 4px;
  background: #ffffff;
}

.prtk__hint {
  color: #17141a;
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .prtk__panel {
    padding: 12px;
    gap: 8px;
  }
  .prtk__track {
    height: 88px;
  }
  .prtk__phone {
    width: 128px;
    height: 88px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .prtk__marker, .prtk__list {
    transition: none !important;
  }
}

(function () {
  var phone = document.getElementById('prtkPhone');
  var marker = document.getElementById('prtkMarker');
  var list = document.getElementById('prtkList');
  var hint = document.getElementById('prtkHint');
  var root = document.getElementById('prtk');

  // 계산 겹: Tick 경계(TICK 배수)를 새로 지날 때마다 감쇠 진동 AMP*e^(-t/TAU)*sin(t*W) 을
  // 기준 위치에 얹는다 — 릴리즈 때 한 번이 아니라 손가락이 칸을 지날 때마다 걸리는 래칫 튐이다.
  var TICK = 22, N = 5, TRACK_H = 110, MAX_TICK = TICK * N, RAW_MAX = 150;
  var AMP = 10, TAU = 0.15, W = 26;

  var raw = 0, lastTick = 0, burstActive = false, burstStart = 0;
  var dragging = false, startY = 0, startRaw = 0, released = true;

  function triggerBurst(now) { burstActive = true; burstStart = now; }

  function frame(now) {
    var clamped = Math.min(raw, MAX_TICK);
    var tickIndex = Math.floor(clamped / TICK);
    if (tickIndex > lastTick) { triggerBurst(now); }
    lastTick = tickIndex;

    var basePos = (clamped / MAX_TICK) * TRACK_H;
    var burst = 0;
    if (burstActive) {
      var t = (now - burstStart) / 1000;
      burst = AMP * Math.exp(-t / TAU) * Math.sin(t * W);
      if (t > 0.6) { burstActive = false; }
    }
    marker.style.transform = 'translateY(' + (-(basePos) + burst).toFixed(1) + 'px)';
    list.style.transform = 'translateY(' + (clamped * 0.35).toFixed(1) + 'px)';
    hint.textContent = raw > 4 ? ('Tick ' + Math.min(tickIndex, N) + '/' + N) : 'Pull down';
    requestAnimationFrame(frame);
  }
  requestAnimationFrame(frame);

  var committing = false, commitTimer = null;
  function commit() {
    committing = true;
    hint.textContent = 'Refreshing';
    commitTimer = setTimeout(function () {
      committing = false;
      raw = 0; lastTick = 0;
      hint.textContent = 'Pull down';
    }, 620);
  }

  function onDown(y) { if (committing) { return; } dragging = true; released = false; startY = y; startRaw = raw; }
  function onMove(y) {
    if (!dragging) { return; }
    raw = Math.max(0, Math.min(RAW_MAX, startRaw + (y - startY)));
  }
  function onUp() {
    if (!dragging) { return; }
    dragging = false; released = true;
    if (raw >= MAX_TICK) { commit(); } else { raw = 0; lastTick = 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();

  var autoRaw = 0, autoTimer = null;
  function autoTick() {
    if (committing) { return; }
    autoRaw += 16;
    if (autoRaw >= MAX_TICK) { raw = MAX_TICK; autoRaw = 0; commit(); return; }
    raw = autoRaw;
  }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } if (commitTimer) { clearTimeout(commitTimer); } }
  if (!reduce) { autoTimer = setInterval(autoTick, 160); }
})();

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

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

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

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

    // 계산 겹: 칸 경계(TICK 배수)를 새로 지날 때마다 감쇠 진동 AMP*e^(-t/TAU)*sin(t*W) 을
    // 기준 위치에 얹는다 — 릴리즈 때 한 번이 아니라 손가락이 칸을 지날 때마다 걸리는 래칫 튐이다.
    const TICK = 22, N = 5, TRACK_H = 110, MAX_TICK = TICK * N, RAW_MAX = 150;
    const AMP = 10, TAU = 0.15, W = 26;

    let raw = 0, lastTick = 0, burstActive = false, burstStart = 0;
    let dragging = false, startY = 0, startRaw = 0;
    let rafId: number | null = null;

    function triggerBurst(now: number) { burstActive = true; burstStart = now; }

    function frame(now: number) {
      const clamped = Math.min(raw, MAX_TICK);
      const tickIndex = Math.floor(clamped / TICK);
      if (tickIndex > lastTick) triggerBurst(now);
      lastTick = tickIndex;

      const basePos = (clamped / MAX_TICK) * TRACK_H;
      let burst = 0;
      if (burstActive) {
        const t = (now - burstStart) / 1000;
        burst = AMP * Math.exp(-t / TAU) * Math.sin(t * W);
        if (t > 0.6) burstActive = false;
      }
      marker!.style.transform = "translateY(" + (-(basePos) + burst).toFixed(1) + "px)";
      list!.style.transform = "translateY(" + (clamped * 0.35).toFixed(1) + "px)";
      hint!.textContent = raw > 4 ? ("칸 " + Math.min(tickIndex, N) + "/" + N) : "아래로 당기세요";
      rafId = requestAnimationFrame(frame);
    }
    rafId = requestAnimationFrame(frame);

    let committing = false, commitTimer: number | null = null;
    function commit() {
      committing = true;
      hint!.textContent = "새로고침 중";
      commitTimer = window.setTimeout(() => {
        committing = false;
        raw = 0; lastTick = 0;
        hint!.textContent = "아래로 당기세요";
      }, 620);
    }

    function onDown(y: number) {
      if (committing) return;
      dragging = true; startY = y; startRaw = raw;
    }
    function onMove(y: number) {
      if (!dragging) return;
      raw = Math.max(0, Math.min(RAW_MAX, startRaw + (y - startY)));
    }
    function onUp() {
      if (!dragging) return;
      dragging = false;
      if (raw >= MAX_TICK) { commit(); } else { raw = 0; lastTick = 0; }
    }

    function onPointerDown(e: PointerEvent) { stopAutoplay(); onDown(e.clientY); }
    function onPointerMove(e: PointerEvent) { onMove(e.clientY); }
    phone.style.touchAction = "none";
    phone.addEventListener("pointerdown", onPointerDown);
    window.addEventListener("pointermove", onPointerMove);
    window.addEventListener("pointerup", onUp);

    let autoRaw = 0, autoTimer: number | null = null;
    function autoTick() {
      if (committing) return;
      autoRaw += 16;
      if (autoRaw >= MAX_TICK) { raw = MAX_TICK; autoRaw = 0; commit(); return; }
      raw = autoRaw;
    }
    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, 160); }

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

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.prtk}>
        <div className={styles.panel}>
          <div className={styles.track}>
            <span className={styles.tick} style={{ bottom: "22px" }} />
            <span className={styles.tick} style={{ bottom: "44px" }} />
            <span className={styles.tick} style={{ bottom: "66px" }} />
            <span className={styles.tick} style={{ bottom: "88px" }} />
            <span className={styles.marker} style={{ "--accent": color } as any} />
          </div>
          <div className={styles.phone}>
            <div className={styles.list}>
              <div className={styles.row} />
              <div className={styles.row} />
            </div>
          </div>
        </div>
        <span className={styles.hint}>아래로 당기세요</span>
      </div>
    </div>
  );
}