04Read receipt transition

<main class="stage">
  <div class="row is-demo">
    <span class="glow" aria-hidden="true"></span>
    <div class="bubble">Heading out</div>
    <div class="status">
      <span class="unread">1</span>
      <svg class="check" viewBox="0 0 20 20" width="16" height="16" aria-hidden="true">
        <path d="M4 10.5 8 14.5 16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/>
      </svg>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────────
$duration: $dur-base;      // 숫자 → 체크로 바뀌는 데 걸리는 시간
$easing: $ease-out;
$color: $subject-blue;     // 말풍선 색 (paper 무대라 blue)

@include stage($stage-paper);

.row {
  position: relative;
  display: flex;
  align-items: flex-end;
  gap: 8px;
}
// 읽힌 순간 뒤에서 한 번 번지는 하이라이트 — 배지 하나만으론 화면 대비 피사체가 너무 작아서(캔버스 8%) 곁들였다
.glow {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 260px;
  height: 260px;
  margin: -130px 0 0 -130px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba($subject-blue, .4), rgba($subject-blue, 0) 70%);
  opacity: 0;
  transform: scale(.7);
  pointer-events: none;

  .row.is-demo & { animation: glow-loop $dur-loop $easing infinite; }
}
.bubble {
  position: relative;
  padding: 14px 20px;
  border-radius: $r-card;
  background: $color;
  color: #fff;
  font-weight: 600; font-size: clamp(14px, 4.5vw, 17px); line-height: 1.4; font-family: inherit;
}
.status {
  position: relative;
  width: 26px;
  height: 26px;
  color: $color;
  font-weight: 700; font-size: 18px; line-height: 1; font-family: inherit;
}
.unread, .check {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
}
.check { color: $color; }

.row.is-demo .unread { animation: unread-out-loop $dur-loop $easing infinite; }
.row.is-demo .check  { animation: check-in-loop $dur-loop $easing infinite; }

// 절반까지는 안읽음 숫자, 절반 지나면 체크 + 하이라이트 — 한 주기 안에서 전환이 반복된다
@keyframes unread-out-loop {
  0%   { opacity: 1; transform: scale(1); }
  48%  { opacity: 1; transform: scale(1); }
  58%  { opacity: 0; transform: scale(.4); }
  100% { opacity: 0; transform: scale(.4); }
}
@keyframes check-in-loop {
  0%   { opacity: 0; transform: scale(.4); }
  48%  { opacity: 0; transform: scale(.4); }
  62%  { opacity: 1; transform: scale(1.15); }
  72%  { opacity: 1; transform: scale(1); }
  100% { opacity: 1; transform: scale(1); }
}
@keyframes glow-loop {
  0%   { opacity: 0; transform: scale(.7); }
  44%  { opacity: 0; transform: scale(.7); }
  60%  { opacity: 1; transform: scale(1); }
  90%  { opacity: 0; transform: scale(1.35); }
  100% { opacity: 0; transform: scale(1.35); }
}

@media (prefers-reduced-motion: reduce) {
  .row.is-demo .unread, .row.is-demo .check, .glow { animation: none !important; }
  .row.is-demo .unread { opacity: 0; }
  .row.is-demo .check { opacity: 1; transform: none; }
  .glow { opacity: 0; }
}

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);
}

.row {
  position: relative;
  display: flex;
  align-items: flex-end;
  gap: 8px;
}

.glow {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 260px;
  height: 260px;
  margin: -130px 0 0 -130px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(47, 109, 246, 0.4), rgba(47, 109, 246, 0) 70%);
  opacity: 0;
  transform: scale(0.7);
  pointer-events: none;
}
.row.is-demo .glow {
  animation: glow-loop 2s ease-out infinite;
}

.bubble {
  position: relative;
  padding: 14px 20px;
  border-radius: 16px;
  background: #2f6df6;
  color: #fff;
  font-weight: 600;
  font-size: clamp(14px, 4.5vw, 17px);
  line-height: 1.4;
  font-family: inherit;
}

.status {
  position: relative;
  width: 26px;
  height: 26px;
  color: #2f6df6;
  font-weight: 700;
  font-size: 18px;
  line-height: 1;
  font-family: inherit;
}

.unread, .check {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
}

.check {
  color: #2f6df6;
}

.row.is-demo .unread {
  animation: unread-out-loop 2s ease-out infinite;
}

.row.is-demo .check {
  animation: check-in-loop 2s ease-out infinite;
}

@keyframes unread-out-loop {
  0% {
    opacity: 1;
    transform: scale(1);
  }
  48% {
    opacity: 1;
    transform: scale(1);
  }
  58% {
    opacity: 0;
    transform: scale(0.4);
  }
  100% {
    opacity: 0;
    transform: scale(0.4);
  }
}
@keyframes check-in-loop {
  0% {
    opacity: 0;
    transform: scale(0.4);
  }
  48% {
    opacity: 0;
    transform: scale(0.4);
  }
  62% {
    opacity: 1;
    transform: scale(1.15);
  }
  72% {
    opacity: 1;
    transform: scale(1);
  }
  100% {
    opacity: 1;
    transform: scale(1);
  }
}
@keyframes glow-loop {
  0% {
    opacity: 0;
    transform: scale(0.7);
  }
  44% {
    opacity: 0;
    transform: scale(0.7);
  }
  60% {
    opacity: 1;
    transform: scale(1);
  }
  90% {
    opacity: 0;
    transform: scale(1.35);
  }
  100% {
    opacity: 0;
    transform: scale(1.35);
  }
}
@media (prefers-reduced-motion: reduce) {
  .row.is-demo .unread, .row.is-demo .check, .glow {
    animation: none !important;
  }
  .row.is-demo .unread {
    opacity: 0;
  }
  .row.is-demo .check {
    opacity: 1;
    transform: none;
  }
  .glow {
    opacity: 0;
  }
}

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

export type ReadReceiptTransitionProps = {
  /** 상대가 읽었는가 */
  read: boolean;
  duration?: number;
  easing?: string;
  color?: string;
  className?: string;
};

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

export default function ReadReceiptTransition({
  read,
  duration = 300,
  easing = "ease-out",
  color = "#2f6df6",
  className = "",
}: ReadReceiptTransitionProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={`${styles.status} ${className}`} style={vars}>
      <span className={`${styles.unread} ${read ? styles.hide : ""}`}>1</span>
      <svg className={`${styles.check} ${read ? styles.show : ""}`} viewBox="0 0 20 20" width="14" height="14" aria-hidden="true">
        <path d="M4 10.5 8 14.5 16 5.5" fill="none" stroke="currentColor" strokeWidth={2.4} strokeLinecap="round" strokeLinejoin="round" />
      </svg>
    </div>
  );
}