03Inline hint that flips while you type

<main class="stage">
  <div class="il is-demo" id="il">
    <label class="il__label" for="il-input">Email</label>
    <div class="il__field">
      <input class="il__input" id="il-input" type="email" autocomplete="off" aria-describedby="il-msg" placeholder="Type an email address">
      <span class="il__ghost" aria-hidden="true">[email protected]</span>
    </div>
    <p class="il__msg" id="il-msg" aria-live="polite">
      <span class="il__bad">The part after @ is still missing</span>
      <span class="il__good">This address can receive mail</span>
    </p>
  </div>
</main>

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

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

@include stage($stage-orange);

$ok: #479075;   // 주황 무대 위에서 읽히는 확정 색
$bad: #4a0f04;  // 주황 위 오류는 더 짙게 (코럴은 무대에 묻힌다)

.il {
  box-sizing: border-box;
  width: min(300px, 86vw);
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.il__label {
  display: block;
  margin-bottom: $sp-1;
  color: $subject-ink;   // 주황 무대 위 크림 2.51:1 → 잉크 5.50:1
  font-size: 11px; line-height: 14px; font-weight: 700;
}

.il__field { position: relative; }
.il__input {
  box-sizing: border-box;
  width: 100%; height: 40px;
  padding: 0 $sp-3;
  border: 2px solid rgba(255, 247, 230, .38);
  border-radius: $r-control;
  background: rgba(23, 20, 26, .18);
  color: $color;
  font-family: inherit;
  font-size: 14px; line-height: 36px; font-weight: 700;
  transition: border-color $duration $easing;
}
.il__input::placeholder { color: rgba(255, 247, 230, .5); font-weight: 600; }
.il__input:focus-visible { outline: 2px solid $color; outline-offset: 2px; }
.il.is-bad .il__input  { border-color: $bad; }
.il.is-good .il__input { border-color: $ok; }

// 자동 루프에서만 보이는 "쳐 넣는 글자". 진짜 placeholder 와 겹치지 않게 지운다
.il.is-demo .il__input::placeholder { color: transparent; }
.il__ghost {
  position: absolute;
  left: 14px; top: 0;
  color: $color;
  font-size: 14px; line-height: 40px; font-weight: 700;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
}

// ── 안내 한 줄 — 자리를 미리 잡아 두고 문구만 갈아 끼운다 ──
.il__msg {
  position: relative;
  height: 16px;
  margin: $sp-2 0 0;
  font-size: 11px; line-height: 16px; font-weight: 700;
}
.il__bad, .il__good {
  position: absolute;
  left: 0; top: 0;
  white-space: nowrap;
  opacity: 0;
}
.il__bad  { color: $bad; }
.il__good { color: $ok; }
.il.is-bad .il__bad   { opacity: 1; }
.il.is-good .il__good { opacity: 1; }

// ── 자동 루프 (2s) ────────────────────────────────────
// 0~14% 절반만 친 주소(오류 문구) → 22~58% 한 조각씩 마저 타이핑 → 62% 통과 문구로 교체(컷)
// → 78% 문구 내림 · 84% 되감기. 88% 안에 처음 상태로 돌아온다.
// 문구 교체는 steps(1, end) 로 컷한다 — opacity 로 겹치면 두 문장이 반투명하게 포개진 프레임이 남는다.
.il.is-demo .il__ghost {
  opacity: 1;
  animation-name: il-type;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.il.is-demo .il__input {
  transition: none;
  animation-name: il-input;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.il.is-demo .il__bad {
  animation-name: il-bad;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.il.is-demo .il__good {
  animation-name: il-good;
  animation-duration: $dur-loop;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes il-type {
  0%   { clip-path: inset(0 62% 0 0); }
  22%  { clip-path: inset(0 46% 0 0); }
  38%  { clip-path: inset(0 30% 0 0); }
  50%  { clip-path: inset(0 14% 0 0); }
  62%  { clip-path: inset(0 0 0 0); }
  84%  { clip-path: inset(0 62% 0 0); }
  100% { clip-path: inset(0 62% 0 0); }
}
@keyframes il-input {
  0%   { border-color: $bad; }
  62%  { border-color: $ok; }
  84%  { border-color: $bad; }
  100% { border-color: $bad; }
}
@keyframes il-bad {
  0%   { opacity: 1; }
  62%  { opacity: 0; }
  84%  { opacity: 1; }
  100% { opacity: 1; }
}
@keyframes il-good {
  0%   { opacity: 0; }
  62%  { opacity: 1; }
  78%  { opacity: 0; }
  100% { opacity: 0; }
}

// 320×200 — 무대 여백을 뺀 174px 안에 들어가도록 간격을 내린다(올리지 않는다)
@media (max-width: 360px) {
  .il__input { height: 36px; line-height: 32px; }
  .il__ghost { line-height: 36px; }
  .il__msg { margin-top: $sp-1; }
}

@media (prefers-reduced-motion: reduce) {
  .il.is-demo .il__ghost,
  .il.is-demo .il__input,
  .il.is-demo .il__bad,
  .il.is-demo .il__good { animation: none !important; }
  .il.is-demo .il__ghost { opacity: 1; clip-path: inset(0 0 0 0); }
  .il.is-demo .il__input { border-color: $ok; }
  .il.is-demo .il__good { opacity: 1; }
  .il__input { transition: none; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.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);
}

.il {
  box-sizing: border-box;
  width: min(300px, 86vw);
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.il__label {
  display: block;
  margin-bottom: 4px;
  color: #17141a;
  font-size: 11px;
  line-height: 14px;
  font-weight: 700;
}

.il__field {
  position: relative;
}

.il__input {
  box-sizing: border-box;
  width: 100%;
  height: 40px;
  padding: 0 12px;
  border: 2px solid rgba(255, 247, 230, 0.38);
  border-radius: 12px;
  background: rgba(23, 20, 26, 0.18);
  color: #fff7e6;
  font-family: inherit;
  font-size: 14px;
  line-height: 36px;
  font-weight: 700;
  transition: border-color 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.il__input::placeholder {
  color: rgba(255, 247, 230, 0.5);
  font-weight: 600;
}

.il__input:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 2px;
}

.il.is-bad .il__input {
  border-color: #4a0f04;
}

.il.is-good .il__input {
  border-color: #479075;
}

.il.is-demo .il__input::placeholder {
  color: transparent;
}

.il__ghost {
  position: absolute;
  left: 14px;
  top: 0;
  color: #fff7e6;
  font-size: 14px;
  line-height: 40px;
  font-weight: 700;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
}

.il__msg {
  position: relative;
  height: 16px;
  margin: 8px 0 0;
  font-size: 11px;
  line-height: 16px;
  font-weight: 700;
}

.il__bad, .il__good {
  position: absolute;
  left: 0;
  top: 0;
  white-space: nowrap;
  opacity: 0;
}

.il__bad {
  color: #4a0f04;
}

.il__good {
  color: #479075;
}

.il.is-bad .il__bad {
  opacity: 1;
}

.il.is-good .il__good {
  opacity: 1;
}

.il.is-demo .il__ghost {
  opacity: 1;
  animation-name: il-type;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.il.is-demo .il__input {
  transition: none;
  animation-name: il-input;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.il.is-demo .il__bad {
  animation-name: il-bad;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.il.is-demo .il__good {
  animation-name: il-good;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes il-type {
  0% {
    clip-path: inset(0 62% 0 0);
  }
  22% {
    clip-path: inset(0 46% 0 0);
  }
  38% {
    clip-path: inset(0 30% 0 0);
  }
  50% {
    clip-path: inset(0 14% 0 0);
  }
  62% {
    clip-path: inset(0 0 0 0);
  }
  84% {
    clip-path: inset(0 62% 0 0);
  }
  100% {
    clip-path: inset(0 62% 0 0);
  }
}
@keyframes il-input {
  0% {
    border-color: #4a0f04;
  }
  62% {
    border-color: #479075;
  }
  84% {
    border-color: #4a0f04;
  }
  100% {
    border-color: #4a0f04;
  }
}
@keyframes il-bad {
  0% {
    opacity: 1;
  }
  62% {
    opacity: 0;
  }
  84% {
    opacity: 1;
  }
  100% {
    opacity: 1;
  }
}
@keyframes il-good {
  0% {
    opacity: 0;
  }
  62% {
    opacity: 1;
  }
  78% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@media (max-width: 360px) {
  .il__input {
    height: 36px;
    line-height: 32px;
  }
  .il__ghost {
    line-height: 36px;
  }
  .il__msg {
    margin-top: 4px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .il.is-demo .il__ghost,
  .il.is-demo .il__input,
  .il.is-demo .il__bad,
  .il.is-demo .il__good {
    animation: none !important;
  }
  .il.is-demo .il__ghost {
    opacity: 1;
    clip-path: inset(0 0 0 0);
  }
  .il.is-demo .il__input {
    border-color: #479075;
  }
  .il.is-demo .il__good {
    opacity: 1;
  }
  .il__input {
    transition: none;
  }
}

// 실제 동작: 한 글자마다 정규식을 다시 재고, 미리 확보해 둔 한 줄이 오류 문구와 완료 문구를 갈아 끼운다.
var il = document.getElementById('il');
var ilInput = document.getElementById('il-input');
var IL_MAIL = /^[\w.+-]+@[\w-]+\.[\w.-]{2,}$/;
function ilPaint() {
  il.classList.remove('is-demo'); // 사람이 손대면 자동 루프를 멈춘다
  var ok = IL_MAIL.test(ilInput.value);
  il.classList.toggle('is-good', ok);
  il.classList.toggle('is-bad', !ok && ilInput.value.length > 0);
  ilInput.setAttribute('aria-invalid', ok ? 'false' : 'true');
}
ilInput.addEventListener('input', ilPaint);
ilInput.addEventListener('focus', ilPaint);

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

export type InlineLiveMessageProps = {
  label?: string;
  placeholder?: string;
  badMessage?: string;
  goodMessage?: string;
  /** 자동 재생 루프 (갤러리용). 사람이 손대면 꺼진다 */
  demo?: boolean;
  duration?: number;
  easing?: string;
  color?: string;
};

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

const MAIL: RegExp = /^[\w.+-]+@[\w-]+\.[\w.-]{2,}$/;

export default function InlineLiveMessage({
  label = "Email",
  placeholder = "Type an email address",
  badMessage = "The part after @ is still missing",
  goodMessage = "This address can receive mail",
  demo = true,
  duration = 220,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#fff7e6",
}: InlineLiveMessageProps) {
  const [value, setValue] = useState("");
  const [live, setLive] = useState(demo);

  const good = MAIL.test(value);
  const bad = !good && value.length > 0;
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  const cls = [styles.root, live ? styles.isDemo : "", bad ? styles.isBad : "", good ? styles.isGood : ""].join(" ");

  return (
    <div className={cls} style={vars}>
      <label className={styles.label} htmlFor="il-input">{label}</label>
      <div className={styles.field}>
        <input
          className={styles.input}
          id="il-input"
          type="email"
          autoComplete="off"
          placeholder={placeholder}
          aria-describedby="il-msg"
          aria-invalid={!good}
          value={value}
          onChange={(e: ChangeEvt) => { setValue(e.target.value); setLive(false); }}
          onFocus={() => setLive(false)}
        />
        <span className={styles.ghost} aria-hidden="true">[email protected]</span>
      </div>
      <p className={styles.msg} id="il-msg" aria-live="polite">
        <span className={styles.bad}>{badMessage}</span>
        <span className={styles.good}>{goodMessage}</span>
      </p>
    </div>
  );
}