05Password change that opens when three fields agree

<main class="stage">
  <section class="pw is-demo" data-strength="0" data-msg="idle" data-bad="false">
    <div class="pw__card">

      <div class="pw__row">
        <div class="pw__box">
          <label class="pw__lab" for="pw-cur">Current password</label>
          <div class="pw__field">
            <input class="pw__in" id="pw-cur" type="password" autocomplete="current-password">
            <span class="pw__ghost" data-g="cur" aria-hidden="true">••••••••</span>
          </div>
        </div>
      </div>

      <div class="pw__row">
        <div class="pw__box">
          <label class="pw__lab" for="pw-new">New password</label>
          <div class="pw__field">
            <input class="pw__in" id="pw-new" type="password" autocomplete="new-password">
            <span class="pw__ghost" data-g="new" aria-hidden="true">••••••••••••</span>
          </div>
        </div>
        <div class="pw__meter" aria-hidden="true">
          <span class="pw__cell"><i class="pw__fill" data-n="1"></i></span>
          <span class="pw__cell"><i class="pw__fill" data-n="2"></i></span>
          <span class="pw__cell"><i class="pw__fill" data-n="3"></i></span>
          <span class="pw__cell"><i class="pw__fill" data-n="4"></i></span>
        </div>
      </div>

      <div class="pw__row">
        <div class="pw__box" data-box="confirm">
          <label class="pw__lab" for="pw-confirm">Confirm new password</label>
          <div class="pw__field">
            <input class="pw__in" id="pw-confirm" type="password" autocomplete="new-password" aria-describedby="pw-hint">
            <span class="pw__ghost" data-g="confirm" aria-hidden="true">••••••••••••</span>
          </div>
        </div>
      </div>

      <p class="pw__hint" id="pw-hint" role="status" aria-live="polite">
        <span class="pw__msg" data-msg="idle">Eight characters or more, mixing numbers and symbols</span>
        <span class="pw__msg" data-msg="bad">The confirmation does not match</span>
        <span class="pw__msg" data-msg="ok">Both fields match</span>
        <span class="pw__msg" data-msg="saved">Password changed</span>
      </p>

      <button class="pw__save" id="pw-save" type="button" aria-disabled="true">Change password</button>
    </div>
  </section>
</main>

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

$duration: $dur-quick;
$easing: $ease-spring;
$color: $subject-blue;

@include stage($stage-ink);

.pw {
  box-sizing: border-box;
  width: min(320px, 90vw);
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-ink;
}

.pw__card {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
  padding: $sp-3;
  border-radius: $r-card;
  background-color: $subject-cream;
  box-shadow: $shadow-raised;
}

.pw__row { display: block; }

.pw__box {
  box-sizing: border-box;
  padding: $sp-1 $sp-3;
  border: 1px solid rgba($subject-ink, .16);
  border-radius: $r-sm;
  background-color: $stage-paper;
  transition: border-color $duration $easing;
}
.pw__box:focus-within { border-color: $color; }

.pw__lab {
  display: block;
  font-size: 10px;
  line-height: 12px;
  font-weight: 700;
  letter-spacing: .02em;
  color: rgba($subject-ink, .72);   // AA 4.5 (blog-design)
}

.pw__field {
  position: relative;
  height: 20px;
}
.pw__in {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 20px;
  border: 0;
  border-radius: 0;
  background-color: transparent;
  color: $subject-ink;
  font-family: inherit;
  font-size: 13px;
  line-height: 20px;
  font-weight: 600;
  letter-spacing: .1em;
}
.pw__in:focus { outline: none; }
.pw__box:focus-within { box-shadow: 0 0 0 3px rgba($subject-blue, .2); }

// 자동 루프에서만 보이는 「쳐 넣는 글자」 — 사람이 치기 시작하면 사라진다
.pw__ghost {
  position: absolute;
  left: 0;
  top: 0;
  display: block;
  width: 100%;
  font-size: 13px;
  line-height: 20px;
  font-weight: 700;
  letter-spacing: .14em;
  color: $subject-ink;
  white-space: nowrap;
  clip-path: inset(0 100% 0 0);
}
.pw:not(.is-demo) .pw__ghost { display: none; }

// ── 네 칸 강도 눈금 — 칸 폭은 grid 가 나눈다 (scaleX 는 칸 안쪽 채우기에만) ──
.pw__meter {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: $sp-1;
  margin-top: $sp-1;
}
.pw__cell {
  display: block;
  overflow: hidden;
  height: 6px;
  border-radius: $r-pill;
  background-color: rgba($subject-ink, .14);
}
.pw__fill {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: $r-pill;
  background-color: $color;
  transform: scaleX(0);
  transform-origin: left center; // 규칙8: 좌변서 차오름
}
.pw__fill[data-n="4"] { background-color: $subject-mint; }

.pw:not(.is-demo)[data-strength="1"] .pw__cell:nth-child(-n + 1) .pw__fill,
.pw:not(.is-demo)[data-strength="2"] .pw__cell:nth-child(-n + 2) .pw__fill,
.pw:not(.is-demo)[data-strength="3"] .pw__cell:nth-child(-n + 3) .pw__fill,
.pw:not(.is-demo)[data-strength="4"] .pw__cell:nth-child(-n + 4) .pw__fill { transform: scaleX(1); }

// ── 이유 문구 (aria-describedby 가 가리키는 줄) ──
.pw__hint {
  position: relative;
  margin: 0;
  height: 16px;
}
.pw__msg {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  font-size: 11px;
  line-height: 16px;
  font-weight: 600;
  color: rgba($subject-ink, .6);
  white-space: nowrap;
  opacity: 0;
}
.pw__msg[data-msg="bad"] { color: $error; }
.pw__msg[data-msg="ok"],
.pw__msg[data-msg="saved"] { color: $color; }

// ── 저장 ──
.pw__save {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 34px;
  border: 0;
  border-radius: $r-control;
  background-color: rgba($subject-ink, .14);
  color: rgba($subject-ink, .8);   // AA 4.5 (.45 는 2.76:1 이었다)
  font-family: inherit;
  font-size: 13px;
  line-height: 20px;
  font-weight: 700;
  cursor: pointer;
  transition: background-color $duration $easing, color $duration $easing;
}
.pw__save:focus-visible { outline: 3px solid $color; outline-offset: 3px; }

// ── 사람이 조작한 정적 상태 — 루프를 껐을 때도 화면이 비지 않는다 ──
.pw:not(.is-demo)[data-msg="idle"] .pw__msg[data-msg="idle"],
.pw:not(.is-demo)[data-msg="bad"] .pw__msg[data-msg="bad"],
.pw:not(.is-demo)[data-msg="ok"] .pw__msg[data-msg="ok"],
.pw:not(.is-demo)[data-msg="saved"] .pw__msg[data-msg="saved"] { opacity: 1; }
.pw:not(.is-demo)[data-bad="true"] .pw__box[data-box="confirm"] {
  border-color: $error;
  background-color: $error-soft;
}
.pw__save[aria-disabled="false"] { background-color: $color; color: $subject-cream; }

// ── 자동 루프 (2s): 현재 → 새 비밀번호 + 눈금 → 확인 어긋남 → 맞춤 → 저장 열림(79.17%) ──
.pw.is-demo .pw__ghost {
  animation-duration: $dur-loop;
  animation-iteration-count: infinite;
  animation-timing-function: steps(10, end);
}
.pw.is-demo .pw__ghost[data-g="cur"] { animation-name: pw-type-cur; }
.pw.is-demo .pw__ghost[data-g="new"] { animation-name: pw-type-new; }
.pw.is-demo .pw__ghost[data-g="confirm"] { animation-name: pw-type-confirm; }

@keyframes pw-type-cur {
  0%     { clip-path: inset(0 100% 0 0); }
  12.5%  { clip-path: inset(0 0 0 0); }
  100%   { clip-path: inset(0 0 0 0); }
}
@keyframes pw-type-new {
  0%     { clip-path: inset(0 100% 0 0); }
  16.67% { clip-path: inset(0 100% 0 0); }
  39.58% { clip-path: inset(0 0 0 0); }
  100%   { clip-path: inset(0 0 0 0); }
}
@keyframes pw-type-confirm {
  0%     { clip-path: inset(0 100% 0 0); }
  45.83% { clip-path: inset(0 100% 0 0); }
  54.17% { clip-path: inset(0 46% 0 0); }
  66.67% { clip-path: inset(0 46% 0 0); }
  79.17% { clip-path: inset(0 0 0 0); }
  100%   { clip-path: inset(0 0 0 0); }
}

// 눈금은 한 칸씩 찬다 — 칸마다 자기 시각을 가진 keyframes (animation 단축은 delay 를 지운다)
.pw.is-demo .pw__fill {
  animation-duration: $dur-loop;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
.pw.is-demo .pw__fill[data-n="1"] { animation-name: pw-fill-1; }
.pw.is-demo .pw__fill[data-n="2"] { animation-name: pw-fill-2; }
.pw.is-demo .pw__fill[data-n="3"] { animation-name: pw-fill-3; }
.pw.is-demo .pw__fill[data-n="4"] { animation-name: pw-fill-4; }

@keyframes pw-fill-1 {
  0%     { transform: scaleX(0); }
  18.75% { transform: scaleX(0); }
  25%    { transform: scaleX(1); }
  100%   { transform: scaleX(1); }
}
@keyframes pw-fill-2 {
  0%     { transform: scaleX(0); }
  25%    { transform: scaleX(0); }
  31.25% { transform: scaleX(1); }
  100%   { transform: scaleX(1); }
}
@keyframes pw-fill-3 {
  0%     { transform: scaleX(0); }
  31.25% { transform: scaleX(0); }
  37.5%  { transform: scaleX(1); }
  100%   { transform: scaleX(1); }
}
@keyframes pw-fill-4 {
  0%     { transform: scaleX(0); }
  37.5%  { transform: scaleX(0); }
  43.75% { transform: scaleX(1); }
  100%   { transform: scaleX(1); }
}

// 확인 칸은 어긋난 동안만 붉게 남는다
.pw.is-demo .pw__box[data-box="confirm"] {
  animation-name: pw-confirm-skin;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
@keyframes pw-confirm-skin {
  0%     { border-color: rgba($subject-ink, .16); background-color: $stage-paper; }
  54.17% { border-color: $error; background-color: $error-soft; }
  79.17% { border-color: $color; background-color: $stage-paper; }
  100%   { border-color: $color; background-color: $stage-paper; }
}

// 이유 문구도 한 프레임에 갈린다
.pw.is-demo .pw__msg {
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.pw.is-demo .pw__msg[data-msg="idle"] { animation-name: pw-msg-idle; }
.pw.is-demo .pw__msg[data-msg="bad"] { animation-name: pw-msg-bad; }
.pw.is-demo .pw__msg[data-msg="ok"] { animation-name: pw-msg-ok; }
.pw.is-demo .pw__msg[data-msg="saved"] { animation-name: pw-msg-none; }

@keyframes pw-msg-idle {
  0%     { opacity: 1; }
  54.17% { opacity: 0; }
  100%   { opacity: 0; }
}
@keyframes pw-msg-bad {
  0%     { opacity: 0; }
  54.17% { opacity: 1; }
  79.17% { opacity: 0; }
  100%   { opacity: 0; }
}
@keyframes pw-msg-ok {
  0%     { opacity: 0; }
  79.17% { opacity: 1; }
  100%   { opacity: 1; }
}
@keyframes pw-msg-none {
  0%     { opacity: 0; }
  100%   { opacity: 0; }
}

// 저장이 열리는 순간이 이 루프의 최대 변화 — 색은 컷으로, 반동은 부드럽게
.pw.is-demo .pw__save {
  animation-name: pw-save-skin, pw-save-pop;
  animation-duration: $dur-loop, $dur-loop;
  animation-timing-function: steps(1, end), $ease-pop;
  animation-iteration-count: infinite, infinite;
}
@keyframes pw-save-skin {
  0%     { background-color: rgba($subject-ink, .14); color: rgba($subject-ink, .8); }
  79.17% { background-color: $color; color: $subject-cream; }
  100%   { background-color: $color; color: $subject-cream; }
}
@keyframes pw-save-pop {
  0%     { transform: scale(1); }
  79.17% { transform: scale(.96); }
  83.33% { transform: scale(1.04); }
  89.58% { transform: scale(1); }
  100%   { transform: scale(1); }
}

@media (max-width: 340px) {
  .pw__card { gap: $sp-1; padding: $sp-2; }
  .pw__box { padding: 0 $sp-2; }
  .pw__lab { font-size: 9px; line-height: 12px; }
  .pw__field { height: 18px; }
  .pw__in { height: 18px; font-size: 11px; line-height: 18px; }
  .pw__ghost { font-size: 11px; line-height: 18px; }
  .pw__cell { height: 4px; }
  .pw__hint { height: 12px; }
  .pw__msg { font-size: 9px; line-height: 12px; }
  .pw__save { height: 24px; font-size: 11px; line-height: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  .pw.is-demo .pw__ghost,
  .pw.is-demo .pw__fill,
  .pw.is-demo .pw__box[data-box="confirm"],
  .pw.is-demo .pw__msg,
  .pw.is-demo .pw__save { animation: none !important; }
  .pw.is-demo .pw__ghost { clip-path: inset(0 0 0 0) !important; }
  .pw.is-demo .pw__fill[data-n="1"],
  .pw.is-demo .pw__fill[data-n="2"],
  .pw.is-demo .pw__fill[data-n="3"],
  .pw.is-demo .pw__fill[data-n="4"] { transform: scaleX(1) !important; }
  .pw.is-demo .pw__msg[data-msg="ok"] { opacity: 1 !important; }
  .pw.is-demo .pw__save { background-color: $color !important; color: $subject-cream !important; }
  .pw__box,
  .pw__save { 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: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.pw {
  box-sizing: border-box;
  width: min(320px, 90vw);
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #17141a;
}

.pw__card {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 12px;
  border-radius: 16px;
  background-color: #fff7e6;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.pw__row {
  display: block;
}

.pw__box {
  box-sizing: border-box;
  padding: 4px 12px;
  border: 1px solid rgba(23, 20, 26, 0.16);
  border-radius: 8px;
  background-color: #ffffff;
  transition: border-color 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.pw__box:focus-within {
  border-color: #2f6df6;
}

.pw__lab {
  display: block;
  font-size: 10px;
  line-height: 12px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: rgba(23, 20, 26, 0.72);
}

.pw__field {
  position: relative;
  height: 20px;
}

.pw__in {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 20px;
  border: 0;
  border-radius: 0;
  background-color: transparent;
  color: #17141a;
  font-family: inherit;
  font-size: 13px;
  line-height: 20px;
  font-weight: 600;
  letter-spacing: 0.1em;
}

.pw__in:focus {
  outline: none;
}

.pw__box:focus-within {
  box-shadow: 0 0 0 3px rgba(47, 109, 246, 0.2);
}

.pw__ghost {
  position: absolute;
  left: 0;
  top: 0;
  display: block;
  width: 100%;
  font-size: 13px;
  line-height: 20px;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: #17141a;
  white-space: nowrap;
  clip-path: inset(0 100% 0 0);
}

.pw:not(.is-demo) .pw__ghost {
  display: none;
}

.pw__meter {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 4px;
  margin-top: 4px;
}

.pw__cell {
  display: block;
  overflow: hidden;
  height: 6px;
  border-radius: 999px;
  background-color: rgba(23, 20, 26, 0.14);
}

.pw__fill {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: 999px;
  background-color: #2f6df6;
  transform: scaleX(0);
  transform-origin: left center;
}

.pw__fill[data-n="4"] {
  background-color: #4cd4a6;
}

.pw:not(.is-demo)[data-strength="1"] .pw__cell:nth-child(-n+1) .pw__fill,
.pw:not(.is-demo)[data-strength="2"] .pw__cell:nth-child(-n+2) .pw__fill,
.pw:not(.is-demo)[data-strength="3"] .pw__cell:nth-child(-n+3) .pw__fill,
.pw:not(.is-demo)[data-strength="4"] .pw__cell:nth-child(-n+4) .pw__fill {
  transform: scaleX(1);
}

.pw__hint {
  position: relative;
  margin: 0;
  height: 16px;
}

.pw__msg {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  font-size: 11px;
  line-height: 16px;
  font-weight: 600;
  color: rgba(23, 20, 26, 0.6);
  white-space: nowrap;
  opacity: 0;
}

.pw__msg[data-msg=bad] {
  color: #c2361a;
}

.pw__msg[data-msg=ok],
.pw__msg[data-msg=saved] {
  color: #2f6df6;
}

.pw__save {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 34px;
  border: 0;
  border-radius: 12px;
  background-color: rgba(23, 20, 26, 0.14);
  color: rgba(23, 20, 26, 0.8);
  font-family: inherit;
  font-size: 13px;
  line-height: 20px;
  font-weight: 700;
  cursor: pointer;
  transition: background-color 220ms cubic-bezier(0.2, 0.8, 0.2, 1), color 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.pw__save:focus-visible {
  outline: 3px solid #2f6df6;
  outline-offset: 3px;
}

.pw:not(.is-demo)[data-msg=idle] .pw__msg[data-msg=idle],
.pw:not(.is-demo)[data-msg=bad] .pw__msg[data-msg=bad],
.pw:not(.is-demo)[data-msg=ok] .pw__msg[data-msg=ok],
.pw:not(.is-demo)[data-msg=saved] .pw__msg[data-msg=saved] {
  opacity: 1;
}

.pw:not(.is-demo)[data-bad=true] .pw__box[data-box=confirm] {
  border-color: #c2361a;
  background-color: #ffe0d8;
}

.pw__save[aria-disabled=false] {
  background-color: #2f6df6;
  color: #fff7e6;
}

.pw.is-demo .pw__ghost {
  animation-duration: 2s;
  animation-iteration-count: infinite;
  animation-timing-function: steps(10, end);
}

.pw.is-demo .pw__ghost[data-g=cur] {
  animation-name: pw-type-cur;
}

.pw.is-demo .pw__ghost[data-g=new] {
  animation-name: pw-type-new;
}

.pw.is-demo .pw__ghost[data-g=confirm] {
  animation-name: pw-type-confirm;
}

@keyframes pw-type-cur {
  0% {
    clip-path: inset(0 100% 0 0);
  }
  12.5% {
    clip-path: inset(0 0 0 0);
  }
  100% {
    clip-path: inset(0 0 0 0);
  }
}
@keyframes pw-type-new {
  0% {
    clip-path: inset(0 100% 0 0);
  }
  16.67% {
    clip-path: inset(0 100% 0 0);
  }
  39.58% {
    clip-path: inset(0 0 0 0);
  }
  100% {
    clip-path: inset(0 0 0 0);
  }
}
@keyframes pw-type-confirm {
  0% {
    clip-path: inset(0 100% 0 0);
  }
  45.83% {
    clip-path: inset(0 100% 0 0);
  }
  54.17% {
    clip-path: inset(0 46% 0 0);
  }
  66.67% {
    clip-path: inset(0 46% 0 0);
  }
  79.17% {
    clip-path: inset(0 0 0 0);
  }
  100% {
    clip-path: inset(0 0 0 0);
  }
}
.pw.is-demo .pw__fill {
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

.pw.is-demo .pw__fill[data-n="1"] {
  animation-name: pw-fill-1;
}

.pw.is-demo .pw__fill[data-n="2"] {
  animation-name: pw-fill-2;
}

.pw.is-demo .pw__fill[data-n="3"] {
  animation-name: pw-fill-3;
}

.pw.is-demo .pw__fill[data-n="4"] {
  animation-name: pw-fill-4;
}

@keyframes pw-fill-1 {
  0% {
    transform: scaleX(0);
  }
  18.75% {
    transform: scaleX(0);
  }
  25% {
    transform: scaleX(1);
  }
  100% {
    transform: scaleX(1);
  }
}
@keyframes pw-fill-2 {
  0% {
    transform: scaleX(0);
  }
  25% {
    transform: scaleX(0);
  }
  31.25% {
    transform: scaleX(1);
  }
  100% {
    transform: scaleX(1);
  }
}
@keyframes pw-fill-3 {
  0% {
    transform: scaleX(0);
  }
  31.25% {
    transform: scaleX(0);
  }
  37.5% {
    transform: scaleX(1);
  }
  100% {
    transform: scaleX(1);
  }
}
@keyframes pw-fill-4 {
  0% {
    transform: scaleX(0);
  }
  37.5% {
    transform: scaleX(0);
  }
  43.75% {
    transform: scaleX(1);
  }
  100% {
    transform: scaleX(1);
  }
}
.pw.is-demo .pw__box[data-box=confirm] {
  animation-name: pw-confirm-skin;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes pw-confirm-skin {
  0% {
    border-color: rgba(23, 20, 26, 0.16);
    background-color: #ffffff;
  }
  54.17% {
    border-color: #c2361a;
    background-color: #ffe0d8;
  }
  79.17% {
    border-color: #2f6df6;
    background-color: #ffffff;
  }
  100% {
    border-color: #2f6df6;
    background-color: #ffffff;
  }
}
.pw.is-demo .pw__msg {
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.pw.is-demo .pw__msg[data-msg=idle] {
  animation-name: pw-msg-idle;
}

.pw.is-demo .pw__msg[data-msg=bad] {
  animation-name: pw-msg-bad;
}

.pw.is-demo .pw__msg[data-msg=ok] {
  animation-name: pw-msg-ok;
}

.pw.is-demo .pw__msg[data-msg=saved] {
  animation-name: pw-msg-none;
}

@keyframes pw-msg-idle {
  0% {
    opacity: 1;
  }
  54.17% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes pw-msg-bad {
  0% {
    opacity: 0;
  }
  54.17% {
    opacity: 1;
  }
  79.17% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes pw-msg-ok {
  0% {
    opacity: 0;
  }
  79.17% {
    opacity: 1;
  }
  100% {
    opacity: 1;
  }
}
@keyframes pw-msg-none {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
.pw.is-demo .pw__save {
  animation-name: pw-save-skin, pw-save-pop;
  animation-duration: 2s, 2s;
  animation-timing-function: steps(1, end), cubic-bezier(0.2, 1.4, 0.4, 1);
  animation-iteration-count: infinite, infinite;
}

@keyframes pw-save-skin {
  0% {
    background-color: rgba(23, 20, 26, 0.14);
    color: rgba(23, 20, 26, 0.8);
  }
  79.17% {
    background-color: #2f6df6;
    color: #fff7e6;
  }
  100% {
    background-color: #2f6df6;
    color: #fff7e6;
  }
}
@keyframes pw-save-pop {
  0% {
    transform: scale(1);
  }
  79.17% {
    transform: scale(0.96);
  }
  83.33% {
    transform: scale(1.04);
  }
  89.58% {
    transform: scale(1);
  }
  100% {
    transform: scale(1);
  }
}
@media (max-width: 340px) {
  .pw__card {
    gap: 4px;
    padding: 8px;
  }
  .pw__box {
    padding: 0 8px;
  }
  .pw__lab {
    font-size: 9px;
    line-height: 12px;
  }
  .pw__field {
    height: 18px;
  }
  .pw__in {
    height: 18px;
    font-size: 11px;
    line-height: 18px;
  }
  .pw__ghost {
    font-size: 11px;
    line-height: 18px;
  }
  .pw__cell {
    height: 4px;
  }
  .pw__hint {
    height: 12px;
  }
  .pw__msg {
    font-size: 9px;
    line-height: 12px;
  }
  .pw__save {
    height: 24px;
    font-size: 11px;
    line-height: 16px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .pw.is-demo .pw__ghost,
  .pw.is-demo .pw__fill,
  .pw.is-demo .pw__box[data-box=confirm],
  .pw.is-demo .pw__msg,
  .pw.is-demo .pw__save {
    animation: none !important;
  }
  .pw.is-demo .pw__ghost {
    clip-path: inset(0 0 0 0) !important;
  }
  .pw.is-demo .pw__fill[data-n="1"],
  .pw.is-demo .pw__fill[data-n="2"],
  .pw.is-demo .pw__fill[data-n="3"],
  .pw.is-demo .pw__fill[data-n="4"] {
    transform: scaleX(1) !important;
  }
  .pw.is-demo .pw__msg[data-msg=ok] {
    opacity: 1 !important;
  }
  .pw.is-demo .pw__save {
    background-color: #2f6df6 !important;
    color: #fff7e6 !important;
  }
  .pw__box,
  .pw__save {
    transition: none !important;
  }
}

// 실제 동작: 세 칸이 조건을 채울 때까지 저장은 aria-disabled 로 잠겨 있고, 눌리면 이유를 읽어 준다
var root = document.querySelector('.pw');
var cur = document.getElementById('pw-cur');
var nw = document.getElementById('pw-new');
var cf = document.getElementById('pw-confirm');
var save = document.getElementById('pw-save');
function strength(v) {
  var n = 0;
  if (v.length >= 8) n++;
  if (/[0-9]/.test(v)) n++;
  if (/[^A-Za-z0-9]/.test(v)) n++;
  if (/[A-Z]/.test(v) && /[a-z]/.test(v)) n++;
  return n;
}
function refresh() {
  root.classList.remove('is-demo');   // 사람이 치기 시작했으니 자동 루프를 끈다
  var s = strength(nw.value);
  var bad = cf.value.length > 0 && cf.value !== nw.value;
  var ok = cur.value.length > 0 && s >= 3 && cf.value.length > 0 && !bad;
  root.setAttribute('data-strength', String(s));
  root.setAttribute('data-bad', String(bad));
  root.setAttribute('data-msg', bad ? 'bad' : (ok ? 'ok' : 'idle'));
  save.setAttribute('aria-disabled', String(!ok));
}
[cur, nw, cf].forEach(function (el) { el.addEventListener('input', refresh); });
save.addEventListener('click', function () {
  root.classList.remove('is-demo');
  if (save.getAttribute('aria-disabled') === 'true') {   // 진짜 disabled 가 아니라 이유를 읽어 준다
    root.setAttribute('data-msg', root.getAttribute('data-bad') === 'true' ? 'bad' : 'idle');
    cf.focus({ preventScroll: true });
    return;
  }
  root.setAttribute('data-msg', 'saved');
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./PasswordChangeForm.module.scss";

export type HintKey = "idle" | "bad" | "ok" | "saved";
export type PasswordChangeFormProps = {
  labels?: { current: string; next: string; confirm: string; save: string };
  hints?: Record<HintKey, string>;
  /** 강도 눈금 네 칸 중 몇 칸이 차야 저장이 열리는가 */
  need?: number;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type InputEvt = { target: { value: string } };
type Fields = { current: string; next: string; confirm: string };

// 네 칸 눈금과 같은 규칙 — 길이 · 숫자 · 기호 · 대소문자 섞임
function strength(v: string): number {
  let n = 0;
  if (v.length >= 8) n += 1;
  if (/[0-9]/.test(v)) n += 1;
  if (/[^A-Za-z0-9]/.test(v)) n += 1;
  if (/[A-Z]/.test(v) && /[a-z]/.test(v)) n += 1;
  return n;
}

export default function PasswordChangeForm({
  labels = {
    current: "Current password",
    next: "New password",
    confirm: "Confirm new password",
    save: "Change password",
  },
  hints = {
    idle: "Eight characters or more, mixed with digits and symbols",
    bad: "The confirm field does not match the new password",
    ok: "Both fields match",
    saved: "Password changed",
  },
  need = 3,
  duration = 220,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: PasswordChangeFormProps) {
  const [demo, setDemo] = useState(true);
  const [v, setV] = useState<Fields>({ current: "", next: "", confirm: "" });
  const [saved, setSaved] = useState(false);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const score = strength(v.next);
  const bad = v.confirm.length > 0 && v.confirm !== v.next;
  const ok = v.current.length > 0 && score >= need && v.confirm.length > 0 && !bad;
  const msg: HintKey = saved && ok ? "saved" : bad ? "bad" : ok ? "ok" : "idle";

  function set(key: keyof Fields) {
    return (e: InputEvt) => {
      setDemo(false); // 사람이 치기 시작했으니 자동 루프를 끈다
      setSaved(false);
      setV((p) => ({ ...p, [key]: e.target.value }));
    };
  }

  // 진짜 disabled 가 아니라 aria-disabled — 눌리면 왜 잠겼는지 읽어 준다
  function submit() {
    setDemo(false);
    setSaved(ok);
  }

  const ghost = (n: number) => "•".repeat(n);

  return (
    <section
      className={`${styles.pw} ${demo ? styles.isDemo : ""}`}
      data-strength={String(score)}
      data-msg={msg}
      data-bad={String(bad)}
      style={vars}
    >
      <div className={styles.card}>
        <div className={styles.row}>
          <div className={styles.box}>
            <label className={styles.lab} htmlFor="pw-cur">{labels.current}</label>
            <div className={styles.field}>
              <input
                className={styles.in}
                id="pw-cur"
                type="password"
                autoComplete="current-password"
                value={v.current}
                onChange={set("current")}
              />
              <span className={styles.ghost} data-g="cur" aria-hidden="true">{ghost(8)}</span>
            </div>
          </div>
        </div>

        <div className={styles.row}>
          <div className={styles.box}>
            <label className={styles.lab} htmlFor="pw-new">{labels.next}</label>
            <div className={styles.field}>
              <input
                className={styles.in}
                id="pw-new"
                type="password"
                autoComplete="new-password"
                value={v.next}
                onChange={set("next")}
              />
              <span className={styles.ghost} data-g="new" aria-hidden="true">{ghost(12)}</span>
            </div>
          </div>
          <div className={styles.meter} aria-hidden="true">
            {[1, 2, 3, 4].map((n) => (
              <span className={styles.cell} key={n}>
                <i className={styles.fill} data-n={String(n)} />
              </span>
            ))}
          </div>
        </div>

        <div className={styles.row}>
          <div className={styles.box} data-box="confirm">
            <label className={styles.lab} htmlFor="pw-confirm">{labels.confirm}</label>
            <div className={styles.field}>
              <input
                className={styles.in}
                id="pw-confirm"
                type="password"
                autoComplete="new-password"
                aria-describedby="pw-hint"
                value={v.confirm}
                onChange={set("confirm")}
              />
              <span className={styles.ghost} data-g="confirm" aria-hidden="true">{ghost(12)}</span>
            </div>
          </div>
        </div>

        <p className={styles.hint} id="pw-hint" role="status" aria-live="polite">
          <span className={styles.msg} data-msg="idle">{hints.idle}</span>
          <span className={styles.msg} data-msg="bad">{hints.bad}</span>
          <span className={styles.msg} data-msg="ok">{hints.ok}</span>
          <span className={styles.msg} data-msg="saved">{hints.saved}</span>
        </p>

        <button className={styles.save} type="button" aria-disabled={!ok} onClick={submit}>
          {labels.save}
        </button>
      </div>
    </section>
  );
}