08Resume marker that keeps the spot you left

<main class="stage">
  <section class="rs is-demo" id="rs" aria-label="Resume from where you left off">
    <header class="rs__head">
      <p class="rs__title">Help · Frequently asked questions</p>
      <p class="rs__state" id="rs-state">Reading from the start</p>
    </header>
    <div class="rs__view" id="rs-view" tabindex="0" role="region" aria-label="Help body">
      <div class="rs__pad" id="rs-pad">
        <p class="rs__p">This document is for people who leave partway and come back.</p>
        <p class="rs__p">The depth you reached stays as a dashed line, and once that line is pushed above the screen a pill rises.</p>
        <p class="rs__p">Imagine you stepped away around the third paragraph.</p>
        <p class="rs__p">The fourth paragraph is about the refund rules.</p>
        <p class="rs__p">The fifth paragraph gives contact details and opening hours.</p>
        <p class="rs__p">Come this far down and you have read almost all of it.</p>
        <span class="rs__mark" id="rs-mark" aria-hidden="true"></span>
      </div>
    </div>
    <button class="rs__pill" type="button" id="rs-pill">
      <svg viewBox="0 0 256 256" width="1em" height="1em" fill="currentColor" aria-hidden="true"><path d="M192,176v48l-64-40L64,224V176l64-40Z" opacity="0.2"/><path d="M184,32H72A16,16,0,0,0,56,48V224a8,8,0,0,0,12.24,6.78L128,193.43l59.77,37.35A8,8,0,0,0,200,224V48A16,16,0,0,0,184,32Zm0,16V161.57l-51.77-32.35a8,8,0,0,0-8.48,0L72,161.56V48ZM132.23,177.22a8,8,0,0,0-8.48,0L72,209.57V180.43l56-35,56,35v29.14Z"/></svg>
      <span class="rs__say" id="rs-say">Back to where you left off?</span>
    </button>
    <p class="rs__live" id="rs-live" aria-live="polite">Just started</p>
  </section>
</main>

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

// 읽던 자리를 남겨 두는 이어읽기 표시 — 가장 깊이 내려갔던 자리의 점선과, 그 자리로 돌아가는 알약
$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-blue;

@include stage($stage-paper);

.rs {
  position: relative;
  box-sizing: border-box;
  width: min(300px, 92vw);
  border-radius: $r-card;
  background: #ffffff;
  color: $subject-ink;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  border: 1px solid rgba(23, 20, 26, .08);
  overflow: hidden;
}

.rs__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: $sp-2;
  padding: $sp-2 $sp-3 0;
}
.rs__title {
  margin: 0;
  font-size: 12px;
  font-weight: 700;
  line-height: 1.3;
}
.rs__state {
  margin: 0;
  font-size: 10px;
  line-height: 1.3;
  color: rgba($stage-ink, .72);
}

.rs__view {
  box-sizing: border-box;
  height: 148px;
  margin: $sp-2 $sp-2 0;
  padding-right: $sp-2;
  overflow-y: auto;
  scrollbar-width: none;
  &::-webkit-scrollbar { display: none; }
  &:focus-visible { outline: 2px solid $color; outline-offset: 2px; }
}
.rs__pad {
  position: relative;
  display: grid;
  gap: $sp-2;
  // 아래 여백이 창 높이(148px)보다 넉넉해야 「점선이 화면 위로 밀려난」 상태가 실제로 만들어진다
  padding: $sp-1 $sp-1 160px;
}
.rs__p {
  margin: 0;
  font-size: 11px;
  line-height: 1.55;
}
// 읽던 자리 점선 — JS 가 가장 깊었던 scrollTop px 를 top 에 얹는다
.rs__mark {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 0;
  border-top: 2px dashed $color;
  pointer-events: none;
}

// 이어읽기 알약 — 카드 밑에서 기다리다 .is-up 이 되면 올라온다
.rs__pill {
  position: absolute;
  right: $sp-3;
  bottom: $sp-6;
  display: inline-flex;
  align-items: center;
  gap: $sp-1;
  margin: 0;
  padding: $sp-1 $sp-3;
  border: 0;
  border-radius: $r-pill;
  background: $subject-ink;
  color: $stage-yellow;
  font-family: inherit;
  font-size: 11px;
  font-weight: 700;
  line-height: 1.4;
  cursor: pointer;
  box-shadow: $shadow-press;
  // 정적 경로 — 기본은 카드 아래에 숨어 있다
  transform: translateY(150%);
  opacity: 0;
  transition: transform $dur-base $easing, opacity $dur-quick $ease-out;
  &:focus-visible { outline: 2px solid $color; outline-offset: 2px; }
}
.rs__pill.is-up {
  transform: translateY(0);
  opacity: 1;
}
.rs__pill svg { font-size: 14px; }

.rs__live {
  position: absolute;
  left: $sp-3;
  bottom: $sp-1;
  margin: 0;
  font-size: 9px;
  line-height: 1.4;
  color: rgba($stage-ink, .72);
}

// ── 격자 미리보기 루프 — 본문이 흘러 내려가고 점선이 남은 뒤 알약이 올라온다 ──
@keyframes rs-flow {
  0%, 24% { transform: translateY(0); }
  56%, 78% { transform: translateY(-28%); }
  88%, 100% { transform: translateY(0); }
}
// 점선은 pad 안에 있어 흐름을 따라가되, 중간에 멈춘 자리를 보여준다
@keyframes rs-mark {
  0%, 24% { opacity: 0; }
  28%, 82% { opacity: 1; }
  84%, 100% { opacity: 0; }
}
@keyframes rs-pill-up {
  0%, 36% { transform: translateY(150%); opacity: 0; }
  42% { opacity: 1; }
  48%, 78% { transform: translateY(0); opacity: 1; }
  88%, 100% { transform: translateY(150%); opacity: 0; }
}
@keyframes rs-say {
  0%, 36% { opacity: .3; }
  40%, 82% { opacity: 1; }
  86%, 100% { opacity: .3; }
}
.rs.is-demo {
  .rs__pad {
    animation-name: rs-flow;
    animation-duration: $duration;
    animation-timing-function: $ease-out;
    animation-iteration-count: infinite;
  }
  .rs__mark {
    top: 96px;
    animation-name: rs-mark;
    animation-duration: $duration;
    animation-timing-function: steps(1, end);
    animation-iteration-count: infinite;
  }
  .rs__pill {
    animation-name: rs-pill-up;
    animation-duration: $duration;
    animation-timing-function: $easing;
    animation-iteration-count: infinite;
    animation-fill-mode: backwards;
  }
  .rs__state {
    animation-name: rs-say;
    animation-duration: $duration;
    animation-timing-function: steps(1, end);
    animation-iteration-count: infinite;
  }
}

@media (max-width: 340px) {
  .rs__view { height: 124px; }
  .rs__p { font-size: 10px; }
  .rs__pill { bottom: $sp-5; }
}

@media (prefers-reduced-motion: reduce) {
  .rs.is-demo .rs__pad,
  .rs.is-demo .rs__pill,
  .rs.is-demo .rs__state { animation: none !important; transform: none !important; }
  // 정지 상태 — 점선은 중간쯤, 알약은 올라온 모습으로 머문다
  .rs.is-demo .rs__pad { transform: translateY(-14%) !important; }
  .rs.is-demo .rs__mark { opacity: 1 !important; top: 96px; }
  .rs.is-demo .rs__pill { transform: translateY(0) !important; opacity: 1 !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);
}

.rs {
  position: relative;
  box-sizing: border-box;
  width: min(300px, 92vw);
  border-radius: 16px;
  background: #ffffff;
  color: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  border: 1px solid rgba(23, 20, 26, 0.08);
  overflow: hidden;
}

.rs__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 12px 0;
}

.rs__title {
  margin: 0;
  font-size: 12px;
  font-weight: 700;
  line-height: 1.3;
}

.rs__state {
  margin: 0;
  font-size: 10px;
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.72);
}

.rs__view {
  box-sizing: border-box;
  height: 148px;
  margin: 8px 8px 0;
  padding-right: 8px;
  overflow-y: auto;
  scrollbar-width: none;
}
.rs__view::-webkit-scrollbar {
  display: none;
}
.rs__view:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}

.rs__pad {
  position: relative;
  display: grid;
  gap: 8px;
  padding: 4px 4px 160px;
}

.rs__p {
  margin: 0;
  font-size: 11px;
  line-height: 1.55;
}

.rs__mark {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 0;
  border-top: 2px dashed #2f6df6;
  pointer-events: none;
}

.rs__pill {
  position: absolute;
  right: 12px;
  bottom: 24px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin: 0;
  padding: 4px 12px;
  border: 0;
  border-radius: 999px;
  background: #17141a;
  color: #ffd23f;
  font-family: inherit;
  font-size: 11px;
  font-weight: 700;
  line-height: 1.4;
  cursor: pointer;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  transform: translateY(150%);
  opacity: 0;
  transition: transform 300ms cubic-bezier(0.2, 0.8, 0.2, 1), opacity 220ms ease-out;
}
.rs__pill:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}

.rs__pill.is-up {
  transform: translateY(0);
  opacity: 1;
}

.rs__pill svg {
  font-size: 14px;
}

.rs__live {
  position: absolute;
  left: 12px;
  bottom: 4px;
  margin: 0;
  font-size: 9px;
  line-height: 1.4;
  color: rgba(23, 20, 26, 0.72);
}

@keyframes rs-flow {
  0%, 24% {
    transform: translateY(0);
  }
  56%, 78% {
    transform: translateY(-28%);
  }
  88%, 100% {
    transform: translateY(0);
  }
}
@keyframes rs-mark {
  0%, 24% {
    opacity: 0;
  }
  28%, 82% {
    opacity: 1;
  }
  84%, 100% {
    opacity: 0;
  }
}
@keyframes rs-pill-up {
  0%, 36% {
    transform: translateY(150%);
    opacity: 0;
  }
  42% {
    opacity: 1;
  }
  48%, 78% {
    transform: translateY(0);
    opacity: 1;
  }
  88%, 100% {
    transform: translateY(150%);
    opacity: 0;
  }
}
@keyframes rs-say {
  0%, 36% {
    opacity: 0.3;
  }
  40%, 82% {
    opacity: 1;
  }
  86%, 100% {
    opacity: 0.3;
  }
}
.rs.is-demo .rs__pad {
  animation-name: rs-flow;
  animation-duration: 2s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}
.rs.is-demo .rs__mark {
  top: 96px;
  animation-name: rs-mark;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.rs.is-demo .rs__pill {
  animation-name: rs-pill-up;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
  animation-fill-mode: backwards;
}
.rs.is-demo .rs__state {
  animation-name: rs-say;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@media (max-width: 340px) {
  .rs__view {
    height: 124px;
  }
  .rs__p {
    font-size: 10px;
  }
  .rs__pill {
    bottom: 20px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .rs.is-demo .rs__pad,
  .rs.is-demo .rs__pill,
  .rs.is-demo .rs__state {
    animation: none !important;
    transform: none !important;
  }
  .rs.is-demo .rs__pad {
    transform: translateY(-14%) !important;
  }
  .rs.is-demo .rs__mark {
    opacity: 1 !important;
    top: 96px;
  }
  .rs.is-demo .rs__pill {
    transform: translateY(0) !important;
    opacity: 1 !important;
  }
}

// 읽던 자리를 남겨 두는 이어읽기 표시 — 가장 깊이 내려갔던 scrollTop 자리에 점선이 남는다
var rs = document.getElementById('rs');
var view = document.getElementById('rs-view');
var mark = document.getElementById('rs-mark');
var pill = document.getElementById('rs-pill');
var say = document.getElementById('rs-say');
var live = document.getElementById('rs-live');
var state = document.getElementById('rs-state');
var deepest = 0;
function paint() {
  var max = view.scrollHeight - view.clientHeight;
  var pct = max > 0 ? Math.round(view.scrollTop / max * 100) : 0;
  // 점선은 가장 깊이 갔던 자리에 — 위로 올려 쓰지 않는다
  mark.style.top = (Math.max(deepest, view.scrollTop)) + 'px';
  deepest = Math.max(deepest, view.scrollTop);
  // 점선이 창 아래로 벗어났을 때만 — 「한 번이라도 깊이 갔다」 가 아니라 「지금 안 보인다」 가 조건이다
  var pushedOut = view.scrollTop + view.clientHeight < deepest + 8 && view.scrollTop < deepest - 8;
  var showPill = pushedOut && deepest > 24;
  pill.classList.toggle('is-up', showPill);
  rs.classList.toggle('rs--deep', showPill);
  // 머리말도 정적 경로에서 같이 움직인다 — 루프를 뗀 뒤 「처음부터」 로 굳지 않게
  state.textContent = showPill ? 'Your spot is saved' : 'Reading from the start';
  if (showPill) {
    var phrase = 'Back to where you left off?';
    if (say.textContent !== phrase) { say.textContent = phrase; live.textContent = 'Your spot sits at ' + pct + '% of the way'; }
  } else {
    live.textContent = pct > 8 ? 'Reading · ' + pct + '%' : 'Just started';
  }
}
view.addEventListener('scroll', function () { rs.classList.remove('is-demo'); paint(); }, { passive: true });
pill.addEventListener('click', function () {
  rs.classList.remove('is-demo');
  view.scrollTo({ top: deepest, behavior: 'smooth' });
});

import { useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./ResumeMarker.module.scss";

export type ResumeMarkerProps = {
  title?: string;
  stateReading?: string;
  stateSaved?: string;
  paragraphs?: string[];
  say?: string;
  pillLabel?: string;
  groupLabel?: string;
  bodyLabel?: string;
  /** 격자 미리보기용 2초 자동 루프. 사람이 손대면 꺼진다 */
  demo?: boolean;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
// ambient 가 얇아 DOM 요소 타입을 못 쓴다 — 필요한 꼴만 로컬 타입으로 선언
type ScrollBox = { scrollTop: number; scrollHeight: number; clientHeight: number; scrollTo: (o: { top: number; behavior: string }) => void };

const DEFAULT_PARAGRAPHS = [
  "이 문서는 중간에 두고 나갔다 돌아오는 사람을 위한 문서예요.",
  "읽던 깊이가 점선으로 남고, 그 줄이 화면 위로 밀려나면 알약이 올라와요.",
  "세 번째 문단쯤에서 잠깐 나갔다 왔다고 상상해 보세요.",
  "네 번째 문단은 환불 규칙에 대한 이야기입니다.",
  "다섯 번째 문단은 문의처와 운영 시간을 안내합니다.",
  "여기까지 내려오면 거의 다 읽은 거예요.",
];

function BookmarkIcon() {
  return (
    <svg viewBox="0 0 256 256" width="1em" height="1em" fill="currentColor" aria-hidden="true"><path d="M192,176v48l-64-40L64,224V176l64-40Z" opacity="0.2"/><path d="M184,32H72A16,16,0,0,0,56,48V224a8,8,0,0,0,12.24,6.78L128,193.43l59.77,37.35A8,8,0,0,0,200,224V48A16,16,0,0,0,184,32Zm0,16V161.57l-51.77-32.35a8,8,0,0,0-8.48,0L72,161.56V48ZM132.23,177.22a8,8,0,0,0-8.48,0L72,209.57V180.43l56-35,56,35v29.14Z"/></svg>
  );
}

export default function ResumeMarker({
  title = "도움말 · 자주 묻는 질문",
  stateReading = "처음부터 읽는 중",
  stateSaved = "읽던 자리가 남아 있어요",
  paragraphs = DEFAULT_PARAGRAPHS,
  say = "읽던 자리로 돌아갈까요?",
  pillLabel = "읽던 자리로 돌아가기",
  groupLabel = "읽던 자리 이어읽기",
  bodyLabel = "도움말 본문",
  demo = true,
  duration = 2000,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: ResumeMarkerProps) {
  const [deep, setDeep] = useState(false);
  const [live, setLive] = useState(demo);
  const [liveText, setLiveText] = useState("읽기 시작");
  const [markTop, setMarkTop] = useState(0);
  const viewRef = useRef<ScrollBox>(null);
  const deepestRef = useRef(0);

  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  // 가장 깊이 내려갔던 scrollTop 자리에 점선이 남는다
  function onScroll() {
    const el = viewRef.current;
    if (!el) return;
    setLive(false);
    const next = Math.max(deepestRef.current || 0, el.scrollTop);
    deepestRef.current = next;
    setMarkTop(next);
    const max = el.scrollHeight - el.clientHeight;
    const pct = max > 0 ? Math.round((el.scrollTop / max) * 100) : 0;
    const pushed = next > 24 && el.scrollTop + el.clientHeight < next + 8 && el.scrollTop < next - 8;
    setDeep(pushed);
    setLiveText(pushed ? "읽던 자리가 " + Math.round((next / (max || 1)) * 100) + "% 지점에 남아 있어요" : pct > 8 ? "읽는 중 · " + pct + "%" : "읽기 시작");
  }

  function back() {
    setLive(false);
    const el = viewRef.current;
    if (!el) return;
    el.scrollTo({ top: deepestRef.current || 0, behavior: "smooth" });
  }

  const cls = [styles.rs, live ? styles.isDemo : ""].filter(Boolean).join(" ");

  return (
    <section className={cls} style={vars} aria-label={groupLabel}>
      <header className={styles.head}>
        <p className={styles.rtitle}>{title}</p>
        <p className={styles.state}>{deep ? stateSaved : stateReading}</p>
      </header>
      <div className={styles.view} ref={viewRef} onScroll={onScroll} tabIndex={0} role="region" aria-label={bodyLabel}>
        <div className={styles.pad}>
          {paragraphs.map((p) => (
            <p className={styles.p} key={p}>{p}</p>
          ))}
          <span className={styles.mark} style={{ top: (live ? 96 : markTop) + "px" }} aria-hidden="true"></span>
        </div>
      </div>
      <button className={`${styles.pill} ${deep ? styles.up : ""}`} type="button" aria-label={pillLabel} onClick={back}>
        <BookmarkIcon />
        <span className={styles.psay}>{say}</span>
      </button>
      <p className={styles.plive} aria-live="polite">{liveText}</p>
    </section>
  );
}