07Empty-state Message That Swaps In When a Remaining-count Value Hits Zero

<main class="stage">
  <div class="es is-demo" id="es">
    <div class="es__head">
      <span class="es__headLabel">Notifications</span>
      <button class="es__clear" id="esClear" type="button">Clear all</button>
    </div>
    <div class="es__body" id="esBody">
      <ul class="es__list" id="esList" role="list"></ul>
      <div class="es__empty" id="esEmpty" hidden>
        <svg class="es__trayIc" viewBox="0 0 256 256" aria-hidden="true" focusable="false">
          <g fill="currentColor">
            <path opacity=".2" d="M216 48v112h-36.69a8 8 0 0 0-5.66 2.34l-19.31 19.32a8 8 0 0 1-5.66 2.34h-41.37a8 8 0 0 1-5.66-2.34l-19.31-19.32a8 8 0 0 0-5.66-2.34H40V48a8 8 0 0 1 8-8h160a8 8 0 0 1 8 8"/>
            <path d="M208 32H48a16 16 0 0 0-16 16v160a16 16 0 0 0 16 16h160a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m0 16v104h-28.7a15.86 15.86 0 0 0-11.3 4.69L148.69 176h-41.38L88 156.68A15.9 15.9 0 0 0 76.69 152H48V48Zm0 160H48v-40h28.69L96 187.32a15.9 15.9 0 0 0 11.31 4.68h41.38a15.86 15.86 0 0 0 11.31-4.69L179.31 168H208z"/>
          </g>
        </svg>
        <p class="es__emptyText">No notifications yet</p>
        <button class="es__refill" id="esRefill" type="button">Get a new notification</button>
      </div>
    </div>
    <p class="es__sr" id="esSr" aria-live="polite"></p>
  </div>
</main>

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

// 계산 겹: index.html 은 목록 → 빈 상태 전환에서 opacity 만 바꾸지 않는다. 목록은 위로
// 이동하며(translateY(-10px)) 사라지고 빈 상태 그림은 아래(12px)에서 올라오며 나타나
// 두 상태가 겹치는 정지 프레임이 "반쯤 섞인 유령"처럼 보이지 않게 한다.
.stage { @include stage($stage-orange); }

.es {
  width: min(100%, 300px);
  background: $subject-cream;
  border-radius: $r-card;
  padding: $sp-4;
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: $sp-3;
}

.es__head { display: flex; align-items: center; justify-content: space-between; gap: $sp-2; }
.es__headLabel { font-size: 13px; font-weight: 700; color: $subject-ink; }

.es__clear {
  border: none;
  background: rgba($subject-ink, .08);
  color: $subject-ink;
  font-size: 11px;
  border-radius: $r-pill;
  padding: $sp-1 $sp-3;
  cursor: pointer;
}
.es__clear:disabled { opacity: .4; cursor: default; }

.es__body { position: relative; min-height: 152px; }

.es__list {
  position: absolute;
  inset: 0;
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: $sp-1;
  opacity: 1;
  transform: translateY(0);
  transition: opacity $dur-base $ease-out, transform $dur-base $ease-out;
}
.es__list--out { opacity: 0; transform: translateY(-10px); }

.es__item {
  border-radius: $r-sm;
  background: rgba($subject-ink, .05);
  color: $subject-ink;
  font-size: 12px;
  padding: $sp-2 $sp-3;
  box-sizing: border-box;
}

.es__empty {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: $sp-2;
  opacity: 0;
  transform: translateY(12px);
  transition: opacity $dur-base $ease-out, transform $dur-base $ease-out;
}
.es__empty--in { opacity: 1; transform: translateY(0); }

.es__trayIc { width: 34px; height: 34px; color: rgba($subject-ink, .4); }
.es__emptyText { margin: 0; font-size: 12px; color: rgba($subject-ink, .7); }

.es__refill {
  border: none;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-size: 11px;
  border-radius: $r-pill;
  padding: $sp-1 $sp-4;
  cursor: pointer;
}

.es__sr {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); margin: -1px; padding: 0; border: 0;
}

@media (max-width: 340px) {
  .es { width: 100%; }
  .es__body { min-height: 110px; }
  .es__list { overflow-y: auto; max-height: 110px; }
}

@media (prefers-reduced-motion: reduce) {
  .es__list,
  .es__empty { transition: none; }
}

.stage html, .stage body {
  margin: 0;
  overflow: hidden;
}
.stage .stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.es {
  width: min(100%, 300px);
  background: #fff7e6;
  border-radius: 16px;
  padding: 16px;
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.es__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.es__headLabel {
  font-size: 13px;
  font-weight: 700;
  color: #17141a;
}

.es__clear {
  border: none;
  background: rgba(23, 20, 26, 0.08);
  color: #17141a;
  font-size: 11px;
  border-radius: 999px;
  padding: 4px 12px;
  cursor: pointer;
}

.es__clear:disabled {
  opacity: 0.4;
  cursor: default;
}

.es__body {
  position: relative;
  min-height: 152px;
}

.es__list {
  position: absolute;
  inset: 0;
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 4px;
  opacity: 1;
  transform: translateY(0);
  transition: opacity 300ms ease-out, transform 300ms ease-out;
}

.es__list--out {
  opacity: 0;
  transform: translateY(-10px);
}

.es__item {
  border-radius: 8px;
  background: rgba(23, 20, 26, 0.05);
  color: #17141a;
  font-size: 12px;
  padding: 8px 12px;
  box-sizing: border-box;
}

.es__empty {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 300ms ease-out, transform 300ms ease-out;
}

.es__empty--in {
  opacity: 1;
  transform: translateY(0);
}

.es__trayIc {
  width: 34px;
  height: 34px;
  color: rgba(23, 20, 26, 0.4);
}

.es__emptyText {
  margin: 0;
  font-size: 12px;
  color: rgba(23, 20, 26, 0.7);
}

.es__refill {
  border: none;
  background: #0a4fe8;
  color: #fff7e6;
  font-size: 11px;
  border-radius: 999px;
  padding: 4px 16px;
  cursor: pointer;
}

.es__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  margin: -1px;
  padding: 0;
  border: 0;
}

@media (max-width: 340px) {
  .es {
    width: 100%;
  }
  .es__body {
    min-height: 110px;
  }
  .es__list {
    overflow-y: auto;
    max-height: 110px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .es__list,
  .es__empty {
    transition: none;
  }
}

(function () {
  "use strict";

  var NAMES = [
    "Payment approved", "New comment added", "Meeting starts in 10 minutes", "Upload finished"
  ];

  var root = document.getElementById("es");
  var list = document.getElementById("esList");
  var empty = document.getElementById("esEmpty");
  var body = document.getElementById("esBody");
  var sr = document.getElementById("esSr");
  var clearBtn = document.getElementById("esClear");
  var refillBtn = document.getElementById("esRefill");
  var reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

  var synthetic = false;
  function human() {
    if (synthetic) return;
    if (root.classList.contains("is-demo")) root.classList.remove("is-demo");
  }

  function makeRow(name) {
    var li = document.createElement("li");
    li.className = "es__item";
    li.setAttribute("role", "listitem");
    li.textContent = name;
    return li;
  }

  function fill() {
    list.innerHTML = "";
    NAMES.forEach(function (name) { list.appendChild(makeRow(name)); });
  }
  fill();

  // 계산 겹: 목록 → 빈 상태 전환은 투명도만 바꾸지 않는다. 목록은 살짝 위로 이동하며
  // 사라지고 빈 상태 그림은 아래에서 올라오며 나타나도록 opacity 와 transform(translateY)
  // 을 함께 바꿔, 정지 사진 한 장만으로는 두 상태가 섞인 유령 프레임처럼 보이지 않게 한다.
  function showEmpty() {
    empty.removeAttribute("hidden");
    requestAnimationFrame(function () {
      list.classList.add("es__list--out");
      empty.classList.add("es__empty--in");
    });
    window.setTimeout(function () {
      list.setAttribute("hidden", "");
    }, reduce ? 0 : 260);
    clearBtn.disabled = true;
    sr.textContent = "No notifications yet";
  }

  function showList() {
    fill();
    list.removeAttribute("hidden");
    requestAnimationFrame(function () {
      list.classList.remove("es__list--out");
      empty.classList.remove("es__empty--in");
    });
    window.setTimeout(function () {
      empty.setAttribute("hidden", "");
    }, reduce ? 0 : 260);
    clearBtn.disabled = false;
    sr.textContent = NAMES.length + " notifications received";
  }

  clearBtn.addEventListener("click", function () {
    human();
    if (clearBtn.disabled) return;
    showEmpty();
  });
  refillBtn.addEventListener("click", function () {
    human();
    showList();
  });

  if (reduce) {
    showEmpty();
  } else {
    var phase = "clear";
    function loop() {
      if (!root.classList.contains("is-demo")) return;
      synthetic = true;
      if (phase === "clear") { showEmpty(); phase = "fill"; } else { showList(); phase = "clear"; }
      synthetic = false;
      window.setTimeout(loop, 1600);
    }
    window.setTimeout(loop, 700);
  }
})();

// NotifEmptyStateCrossfade — vanilla 판(run/405/demo/07-.../index.html) 의 React 포트.
// 계산 겹: 목록 → 빈 상태 전환은 투명도만 바꾸지 않는다. 목록은 살짝 위로 이동하며 사라지고
// 빈 상태 그림은 아래에서 올라오며 나타나도록 opacity 와 transform(translateY)을 함께 바꿔,
// 정지 사진 한 장만으로는 두 상태가 섞인 유령 프레임처럼 보이지 않게 한다 — vanilla 와 동일.
import { useEffect, useRef, useState } from "react";
import styles from "./NotifEmptyStateCrossfade.module.scss";

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

const NAMES = ["결제가 승인됐어요", "새 댓글이 달렸어요", "회의 10분 전이에요", "업로드가 끝났어요"];

export default function NotifEmptyStateCrossfade() {
  const [isDemo, setIsDemo] = useState(true);
  const [clearDisabled, setClearDisabled] = useState(false);

  const isDemoRef = useRef(true) as unknown as Box<boolean>;
  const synthRef = useRef(false) as unknown as Box<boolean>;
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const listRef = useRef(null) as unknown as Box<HTMLUListElement>;
  const emptyRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const srRef = useRef(null) as unknown as Box<HTMLParagraphElement>;
  const reduceRef = useRef(false) as unknown as Box<boolean>;
  const loopTimerRef = useRef(0) as unknown as Box<number>;

  function human() {
    if (synthRef.current) return;
    if (isDemoRef.current) { isDemoRef.current = false; setIsDemo(false); }
  }

  function makeRow(name: string): HTMLLIElement {
    const li = document.createElement("li");
    li.className = styles.item;
    li.setAttribute("role", "listitem");
    li.textContent = name;
    return li;
  }

  function fill() {
    const list = listRef.current;
    if (!list) return;
    list.innerHTML = "";
    NAMES.forEach((name) => { list.appendChild(makeRow(name)); });
  }

  function showEmpty() {
    const reduce = reduceRef.current;
    const list = listRef.current, empty = emptyRef.current;
    if (!list || !empty) return;
    empty.removeAttribute("hidden");
    requestAnimationFrame(() => {
      list.classList.add(styles.listOut);
      empty.classList.add(styles.emptyIn);
    });
    window.setTimeout(() => { list.setAttribute("hidden", ""); }, reduce ? 0 : 260);
    setClearDisabled(true);
    if (srRef.current) srRef.current.textContent = "받은 알림이 없어요";
  }

  function showList() {
    const reduce = reduceRef.current;
    const list = listRef.current, empty = emptyRef.current;
    if (!list || !empty) return;
    fill();
    list.removeAttribute("hidden");
    requestAnimationFrame(() => {
      list.classList.remove(styles.listOut);
      empty.classList.remove(styles.emptyIn);
    });
    window.setTimeout(() => { empty.setAttribute("hidden", ""); }, reduce ? 0 : 260);
    setClearDisabled(false);
    if (srRef.current) srRef.current.textContent = NAMES.length + "개 알림을 받았습니다";
  }

  function onClear() {
    human();
    if (clearDisabled) return;
    showEmpty();
  }

  function onRefill() {
    human();
    showList();
  }

  useEffect(() => {
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    reduceRef.current = reduce;
    fill();

    if (reduce) {
      showEmpty();
    } else {
      let phase = "clear";
      function loop() {
        if (!isDemoRef.current) return;
        synthRef.current = true;
        if (phase === "clear") { showEmpty(); phase = "fill"; } else { showList(); phase = "clear"; }
        synthRef.current = false;
        loopTimerRef.current = window.setTimeout(loop, 1600);
      }
      loopTimerRef.current = window.setTimeout(loop, 700);
    }

    return () => { window.clearTimeout(loopTimerRef.current); };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.es + " " + (isDemo ? styles.isDemo : "")} ref={rootRef}>
        <div className={styles.head}>
          <span className={styles.headLabel}>알림</span>
          <button className={styles.clear} type="button" disabled={clearDisabled} onClick={onClear}>모두 지우기</button>
        </div>
        <div className={styles.body}>
          <ul className={styles.list} role="list" ref={listRef} />
          <div className={styles.empty} ref={emptyRef} hidden>
            <svg className={styles.trayIc} viewBox="0 0 256 256" aria-hidden="true" focusable="false">
              <g fill="currentColor">
                <path opacity=".2" d="M216 48v112h-36.69a8 8 0 0 0-5.66 2.34l-19.31 19.32a8 8 0 0 1-5.66 2.34h-41.37a8 8 0 0 1-5.66-2.34l-19.31-19.32a8 8 0 0 0-5.66-2.34H40V48a8 8 0 0 1 8-8h160a8 8 0 0 1 8 8" />
                <path d="M208 32H48a16 16 0 0 0-16 16v160a16 16 0 0 0 16 16h160a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m0 16v104h-28.7a15.86 15.86 0 0 0-11.3 4.69L148.69 176h-41.38L88 156.68A15.9 15.9 0 0 0 76.69 152H48V48Zm0 160H48v-40h28.69L96 187.32a15.9 15.9 0 0 0 11.31 4.68h41.38a15.86 15.86 0 0 0 11.31-4.69L179.31 168H208z" />
              </g>
            </svg>
            <p className={styles.emptyText}>받은 알림이 없어요</p>
            <button className={styles.refill} type="button" onClick={onRefill}>새 알림 받기</button>
          </div>
        </div>
        <p className={styles.sr} aria-live="polite" ref={srRef} />
      </div>
    </main>
  );
}