02Three-step fallback avatar

<main class="stage">
  <section class="fb is-demo" aria-label="Three-step fallback avatar" data-step="photo">
    <p class="fb__name">Admin</p>

    <!-- 세 겹이 한 자리에 겹쳐 앉는다: 사진 자리(로딩 시머) · 이니셜 · 사람 도형.
         data-step 이 어느 겹을 보일지 정한다 -->
    <span class="fb__slot">
      <span class="fb__shine" aria-hidden="true"></span>
      <img class="fb__photo" src="member-photo.jpg" alt="">
      <span class="fb__initial" aria-hidden="true"></span>
      <span class="fb__mark" aria-hidden="true">
        <svg viewBox="0 0 256 256" width="34" height="34" aria-hidden="true" focusable="false" fill="currentColor"><path d="M192,96a64,64,0,1,1-64-64A64,64,0,0,1,192,96Z" opacity="0.2"/><path d="M230.92,212c-15.23-26.33-38.7-45.21-66.09-54.16a72,72,0,1,0-73.66,0C63.78,166.78,40.31,185.66,25.08,212a8,8,0,1,0,13.85,8c18.84-32.56,52.14-52,89.07-52s70.23,19.44,89.07,52a8,8,0,1,0,13.85-8ZM72,96a56,56,0,1,1,56,56A56.06,56.06,0,0,1,72,96Z"/></svg>
      </span>
    </span>

    <p class="fb__step">
      <span class="fb__stepTxt fb__stepTxt--photo">Step 1 · waiting for photo</span>
      <span class="fb__stepTxt fb__stepTxt--initials">Step 2 · initials fallback</span>
      <span class="fb__stepTxt fb__stepTxt--mark">Step 3 · person-mark fallback</span>
    </p>

    <button class="fb__btn" type="button">
      <span class="fb__btnTxt fb__btnTxt--mark">Show person mark</span>
      <span class="fb__btnTxt fb__btnTxt--initials">Back to initials</span>
    </button>
  </section>
</main>

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

// 279 아바타 팔레트 — 이니셜 글자는 언제나 $subject-cream. 괄호는 크림 글자 기준 실측 대비비
$av-blue:   #7c90be;   // 5.29:1
$av-violet: #9791c9;   // 5.76:1
$av-teal:   #479082;   // 5.79:1
$av-plum:   #ab5488;   // 6.52:1
$av-brick:  $error;    // 오류 토큰 — 5.13:1. 리터럴 금지 (BD10)
$av-slate:  #3b4a63;   // 8.40:1
$av-mist:   #b6b0c0;   // 잉크 무대 보조 글자 8.65:1
$av-deep:   #4a4452;   // 옐로 무대 보조 글자 6.49:1 · 페이퍼 무대 9.38:1

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;   // 세 단계 컷이 도는 한 바퀴
$easing:   $ease-out;   // 시머 막대가 지나가는 결
$color:    $stage-ink;  // 옐로 무대 글자 12.63:1 — 크림은 1.35:1 로 금지

@include stage($stage-yellow);

.fb {
  display: grid;
  justify-items: center;
  gap: $sp-3;
  width: min(320px, 92vw);
}

.fb__name {
  margin: 0;
  color: $color;
  font-weight: 700;
  font-size: 14px;
  line-height: 1.2;
}

// 세 겹이 겹쳐 앉는 자리 — 사진(안 오면 시머) · 이니셜 · 사람 도형
.fb__slot {
  position: relative;
  display: grid;
  place-items: center;
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: $stage-paper;
  overflow: hidden;
}

.fb__photo {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;   // 칩 — 어떤 비율의 사진이 와도 원을 꽉 채운다
  opacity: 0;
}

// 로딩 시머 막대 — 대기 단계에서 계속 지나가며 움직임 프레임을 채운다
.fb__shine {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 34px;
  background: rgba(23, 20, 26, .12);
  animation-name: fbShine;
  animation-duration: 1s;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}

.fb__initial {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: $stage-paper;
  color: $color;   // 옐로 무대 글자는 잉크로
  font-weight: 700;
  font-size: 26px;
  line-height: 1;
  opacity: 0;
}

.fb__mark {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: $stage-paper;
  color: $color;
  opacity: 0;
}
.fb__mark svg { width: 34px; height: 34px; }

// 정적 표시 — data-step 이 보일 겹 하나만 켠다 (.is-demo 를 뗀 화면이 비면 안 된다)
.fb[data-step="photo"] .fb__photo { opacity: 1; }
.fb[data-step="initials"] .fb__initial { opacity: 1; }
.fb[data-step="mark"] .fb__mark { opacity: 1; }

// 단계 한 줄 — 세 문장이 한 칸에 겹쳐 있고 컷 타이밍에 맞춰 바뀐다
.fb__step {
  display: grid;
  justify-items: center;
  margin: 0;
}
.fb__stepTxt {
  grid-area: 1 / 1;
  color: $av-deep;   // 옐로 무대 보조 글자 6.49:1
  font-weight: 600;
  font-size: 12px;
  line-height: 1.3;
  opacity: 0;
}
.fb[data-step="photo"] .fb__stepTxt--photo,
.fb[data-step="initials"] .fb__stepTxt--initials,
.fb[data-step="mark"] .fb__stepTxt--mark { opacity: 1; }

.fb__btn {
  display: grid;
  margin: 0;
  padding: $sp-2 $sp-5;
  border: 0;
  border-radius: $r-control;
  background: $color;
  color: $stage-yellow;
  font-family: inherit;
  font-weight: 700;
  font-size: 13px;
  line-height: 1.2;
  cursor: pointer;
}
.fb__btn:focus-visible { outline: 2px solid $color; outline-offset: 3px; }
.fb__btnTxt { grid-area: 1 / 1; visibility: hidden; }
.fb[data-step="initials"] .fb__btnTxt--mark,
.fb[data-step="mark"] .fb__btnTxt--initials { visibility: visible; }

// ── 격자 미리보기 루프 ────────────────────────────────
// 세 단계를 steps(1, end) 로 한 프레임에 컷한다 — 절반 투명 상태가 겹치지 않는다.
// 0% 대기 / 34% 이니셜 / 67% 사람 도형, 88% 안에 대기로 복귀.
// 컷만 있으면 움직임 프레임이 모자라니 대기 단계의 시머 막대가 계속 지나가 프레임을 채운다
.fb.is-demo .fb__photo,
.fb.is-demo .fb__stepTxt--photo {
  animation-name: fbCutPhoto;
  animation-duration: $duration;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.fb.is-demo .fb__initial,
.fb.is-demo .fb__stepTxt--initials {
  animation-name: fbCutInitial;
  animation-duration: $duration;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.fb.is-demo .fb__mark,
.fb.is-demo .fb__stepTxt--mark {
  animation-name: fbCutMark;
  animation-duration: $duration;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes fbCutPhoto {
  0%      { opacity: 1; }
  34%     { opacity: 0; }
  88%     { opacity: 1; }
  100%    { opacity: 1; }
}
@keyframes fbCutInitial {
  0%      { opacity: 0; }
  34%     { opacity: 1; }
  67%     { opacity: 0; }
  100%    { opacity: 0; }
}
@keyframes fbCutMark {
  0%      { opacity: 0; }
  67%     { opacity: 1; }
  88%     { opacity: 0; }
  100%    { opacity: 0; }
}

@keyframes fbShine {
  0%      { transform: translateX(-40px); }
  100%    { transform: translateX(80px); }
}

// 좁은 화면 — 표시와 여백만 줄인다. 값을 올리지 않는다.
@media (max-width: 340px), (max-height: 220px) {
  .fb { gap: $sp-2; }
  .fb__slot { width: 56px; height: 56px; }
  .fb__initial { font-size: 22px; }
  .fb__mark svg { width: 28px; height: 28px; }
  .fb__name { font-size: 12px; }
  .fb__stepTxt { font-size: 11px; }
  .fb__btn { padding: $sp-2 $sp-4; font-size: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  // .fb.is-demo … (0,3,0) 를 이기려면 !important 가 필요하다.
  // 컷과 시머만 끄고, 정적 규칙(data-step) 이 보일 겹을 이어받는다
  .fb__photo, .fb__initial, .fb__mark, .fb__stepTxt, .fb__shine { 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: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.fb {
  display: grid;
  justify-items: center;
  gap: 12px;
  width: min(320px, 92vw);
}

.fb__name {
  margin: 0;
  color: #17141a;
  font-weight: 700;
  font-size: 14px;
  line-height: 1.2;
}

.fb__slot {
  position: relative;
  display: grid;
  place-items: center;
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: #ffffff;
  overflow: hidden;
}

.fb__photo {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0;
}

.fb__shine {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 34px;
  background: rgba(23, 20, 26, 0.12);
  animation-name: fbShine;
  animation-duration: 1s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}

.fb__initial {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: #ffffff;
  color: #17141a;
  font-weight: 700;
  font-size: 26px;
  line-height: 1;
  opacity: 0;
}

.fb__mark {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: #ffffff;
  color: #17141a;
  opacity: 0;
}

.fb__mark svg {
  width: 34px;
  height: 34px;
}

.fb[data-step=photo] .fb__photo {
  opacity: 1;
}

.fb[data-step=initials] .fb__initial {
  opacity: 1;
}

.fb[data-step=mark] .fb__mark {
  opacity: 1;
}

.fb__step {
  display: grid;
  justify-items: center;
  margin: 0;
}

.fb__stepTxt {
  grid-area: 1/1;
  color: #4a4452;
  font-weight: 600;
  font-size: 12px;
  line-height: 1.3;
  opacity: 0;
}

.fb[data-step=photo] .fb__stepTxt--photo,
.fb[data-step=initials] .fb__stepTxt--initials,
.fb[data-step=mark] .fb__stepTxt--mark {
  opacity: 1;
}

.fb__btn {
  display: grid;
  margin: 0;
  padding: 8px 20px;
  border: 0;
  border-radius: 12px;
  background: #17141a;
  color: #ffd23f;
  font-family: inherit;
  font-weight: 700;
  font-size: 13px;
  line-height: 1.2;
  cursor: pointer;
}

.fb__btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}

.fb__btnTxt {
  grid-area: 1/1;
  visibility: hidden;
}

.fb[data-step=initials] .fb__btnTxt--mark,
.fb[data-step=mark] .fb__btnTxt--initials {
  visibility: visible;
}

.fb.is-demo .fb__photo,
.fb.is-demo .fb__stepTxt--photo {
  animation-name: fbCutPhoto;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.fb.is-demo .fb__initial,
.fb.is-demo .fb__stepTxt--initials {
  animation-name: fbCutInitial;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.fb.is-demo .fb__mark,
.fb.is-demo .fb__stepTxt--mark {
  animation-name: fbCutMark;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes fbCutPhoto {
  0% {
    opacity: 1;
  }
  34% {
    opacity: 0;
  }
  88% {
    opacity: 1;
  }
  100% {
    opacity: 1;
  }
}
@keyframes fbCutInitial {
  0% {
    opacity: 0;
  }
  34% {
    opacity: 1;
  }
  67% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes fbCutMark {
  0% {
    opacity: 0;
  }
  67% {
    opacity: 1;
  }
  88% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes fbShine {
  0% {
    transform: translateX(-40px);
  }
  100% {
    transform: translateX(80px);
  }
}
@media (max-width: 340px), (max-height: 220px) {
  .fb {
    gap: 8px;
  }
  .fb__slot {
    width: 56px;
    height: 56px;
  }
  .fb__initial {
    font-size: 22px;
  }
  .fb__mark svg {
    width: 28px;
    height: 28px;
  }
  .fb__name {
    font-size: 12px;
  }
  .fb__stepTxt {
    font-size: 11px;
  }
  .fb__btn {
    padding: 8px 16px;
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .fb__photo, .fb__initial, .fb__mark, .fb__stepTxt, .fb__shine {
    animation: none !important;
  }
}

(function () {
  var root = document.querySelector('.fb');
  var img = root.querySelector('.fb__photo');
  var btn = root.querySelector('.fb__btn');
  var nameEl = root.querySelector('.fb__name');
  var initialEl = root.querySelector('.fb__initial');

  // 이니셜은 Name 표시에서 계산한다(한국어 첫 글자 1자 · 라틴 앞 두 단어 머리글자)
  function initialsOf(text) {
    var trimmed = text.trim();
    if (!trimmed) return '';
    if (/[가-힣]/.test(trimmed[0])) return trimmed[0];
    var words = trimmed.split(/\s+/).filter(function (w) { return /[A-Za-z]/.test(w[0] || ''); });
    return words.slice(0, 2).map(function (w) { return w[0].toUpperCase(); }).join('');
  }
  initialEl.textContent = initialsOf(nameEl.textContent);

  // 사진 파일은 일부러 없다(404) — error 이벤트에서 스스로 이니셜 단계로 내려간다
  img.addEventListener('error', function () {
    if (root.dataset.step === 'photo') root.dataset.step = 'initials';
  });
  if (img.complete && img.naturalWidth === 0 && root.dataset.step === 'photo') {
    root.dataset.step = 'initials';
  }

  // 버튼 하나가 이니셜과 사람 도형을 오간다 (키보드 Enter·Space 로도 눌린다)
  btn.addEventListener('click', function () {
    root.dataset.step = (root.dataset.step === 'mark') ? 'initials' : 'mark';
  });

  // 사람이 손을 대면 미리보기 루프를 뗀다
  function stopLoop() { root.classList.remove('is-demo'); }
  root.addEventListener('pointerdown', stopLoop);
  root.addEventListener('focusin', stopLoop);
})();

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

export type AvatarFallbackChainProps = {
  label?: string;
  name?: string;
  stepPhoto?: string;
  stepInitials?: string;
  stepMark?: string;
  btnToMark?: string;
  btnToInitials?: string;
  /** 세 단계 컷이 도는 한 바퀴(ms) */
  duration?: number;
  easing?: string;
  /** 옐로 무대 글자색 */
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

// 이니셜은 이름에서 계산한다(한국어 첫 글자 1자 · 라틴 앞 두 단어 머리글자)
function initialsOf(text: string): string {
  const trimmed = text.trim();
  if (!trimmed) return "";
  if (/[가-힣]/.test(trimmed[0])) return trimmed[0];
  const words = trimmed.split(/\s+/).filter((w) => /[A-Za-z]/.test(w[0] || ""));
  return words.slice(0, 2).map((w) => w[0].toUpperCase()).join("");
}

export default function AvatarFallbackChain({
  label = "3단 대체 아바타",
  name = "관리자",
  stepPhoto = "1단계 · 사진 기다리는 중",
  stepInitials = "2단계 · 이니셜 대체",
  stepMark = "3단계 · 사람 도형 대체",
  btnToMark = "사람 도형으로",
  btnToInitials = "이니셜로 되돌리기",
  duration = 2000,
  easing = "ease-out",
  color = "#17141a",
}: AvatarFallbackChainProps): ReactNode {
  const [step, setStep] = useState<"photo" | "initials" | "mark">("photo");
  const [loop, setLoop] = useState<boolean>(true);

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

  return (
    <section
      className={loop ? `${styles.fb} ${styles.isDemo}` : styles.fb}
      style={vars}
      aria-label={label}
      data-step={step}
      onPointerDown={() => setLoop(false)}
      onFocus={() => setLoop(false)}
    >
      <p className={styles.name}>{name}</p>

      {/* 세 겹이 한 자리에 겹쳐 앉는다: 사진 자리(로딩 시머) · 이니셜 · 사람 도형.
          data-step 이 어느 겹을 보일지 정한다 */}
      <span className={styles.slot}>
        <span className={styles.shine} aria-hidden="true" />
        {/* 사진 파일은 일부러 없다(404) — error 에서 스스로 이니셜 단계로 내려간다 */}
        <img
          className={styles.photo}
          src="member-photo.jpg"
          alt=""
          onError={() => setStep((s) => (s === "photo" ? "initials" : s))}
        />
        <span className={styles.initial} aria-hidden="true">{initialsOf(name)}</span>
        <span className={styles.mark} aria-hidden="true">
          <svg viewBox="0 0 256 256" width="34" height="34" aria-hidden="true" focusable="false" fill="currentColor"><path d="M192,96a64,64,0,1,1-64-64A64,64,0,0,1,192,96Z" opacity="0.2" /><path d="M230.92,212c-15.23-26.33-38.7-45.21-66.09-54.16a72,72,0,1,0-73.66,0C63.78,166.78,40.31,185.66,25.08,212a8,8,0,1,0,13.85,8c18.84-32.56,52.14-52,89.07-52s70.23,19.44,89.07,52a8,8,0,1,0,13.85-8ZM72,96a56,56,0,1,1,56,56A56.06,56.06,0,0,1,72,96Z" /></svg>
        </span>
      </span>

      <p className={styles.step}>
        <span className={`${styles.stepTxt} ${styles.stepTxtPhoto}`}>{stepPhoto}</span>
        <span className={`${styles.stepTxt} ${styles.stepTxtInitials}`}>{stepInitials}</span>
        <span className={`${styles.stepTxt} ${styles.stepTxtMark}`}>{stepMark}</span>
      </p>

      {/* 버튼 하나가 이니셜과 사람 도형을 오간다 (키보드 Enter·Space 로도 눌린다) */}
      <button
        className={styles.btn}
        type="button"
        onClick={() => setStep((s) => (s === "mark" ? "initials" : "mark"))}
      >
        <span className={`${styles.btnTxt} ${styles.btnTxtMark}`}>{btnToMark}</span>
        <span className={`${styles.btnTxt} ${styles.btnTxtInitials}`}>{btnToInitials}</span>
      </button>
    </section>
  );
}