01Extending arrow

<main class="stage">
  <a class="ae-link is-demo" href="#">
    <span class="ae-link__label">Learn more</span>
    <span class="ae-link__arrow">
      <span class="ae-link__shaft"></span>
      <span class="ae-link__head"></span>
      <span class="ae-link__trail ae-link__trail--1" aria-hidden="true"></span>
      <span class="ae-link__trail ae-link__trail--2" aria-hidden="true"></span>
    </span>
  </a>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;   // is-demo 강제 루프 주기(캡처용). 실제 호버 전환은 아래 220ms 를 쓴다
$easing: $ease-elastic;  // 고무줄식 오버슛 — 늘어났다 살짝 되돌아와 멈춘다
$color: $subject-cream;

@include stage($stage-ink);

.ae-link {
  display: inline-flex;
  align-items: center;
  gap: $sp-2;
  color: $color;
  text-decoration: none;
  font: 600 16px/1 -apple-system, "Segoe UI", sans-serif;
}

.ae-link__arrow {
  position: relative;
  display: inline-flex;
  align-items: center;
  width: 26px;
  height: 12px;
}

.ae-link__shaft {
  position: absolute;
  left: 0;
  width: 16px;
  height: 2px;
  background: $color;
  transform-origin: left center; // 규칙8: 화살대 왼쪽서 늘어남
  transform: scaleX(1);
  transition: transform 260ms $easing;
}

.ae-link__head {
  position: absolute;
  left: 10px;
  width: 8px;
  height: 8px;
  border-top: 2px solid $color;
  border-right: 2px solid $color;
  transform: translateX(0) rotate(45deg);
  transition: transform 260ms $easing;
}

// 화살촉 트레일 파티클 — 신장하는 동안 화살촉 뒤로 작은 점 두 개가 지연·감쇠하며 따라붙는다
.ae-link__trail {
  position: absolute;
  left: 10px;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: $color;
  opacity: 0;
}

// 실사용: 링크에 마우스를 올리면 몸통(shaft)이 길게 늘어나고 화살촉(head)이 따라 밀려난다. $easing 이 고무줄 오버슛을 만든다
.ae-link:hover .ae-link__shaft { transform: scaleX(1.8); }
.ae-link:hover .ae-link__head { transform: translateX(10px) rotate(45deg); }

@keyframes ae-trail-hover {
  0%   { opacity: 0; transform: translateX(0) scale(.6); }
  45%  { opacity: .5; transform: translateX(5px) scale(1); }
  100% { opacity: 0; transform: translateX(9px) scale(.4); }
}
.ae-link:hover .ae-link__trail--1 { animation: ae-trail-hover 420ms $ease-out forwards; }
.ae-link:hover .ae-link__trail--2 { animation: ae-trail-hover 420ms $ease-out 70ms forwards; }

// 데모 루프: is-demo 는 :hover 를 흉내 낸 keyframes 로 무한 반복 (헤드리스는 :hover 를 못 건다)
@keyframes ae-extend-shaft {
  0%, 20% { transform: scaleX(1); }
  50%, 70% { transform: scaleX(1.8); }
  100% { transform: scaleX(1); }
}
@keyframes ae-extend-head {
  0%, 20% { transform: translateX(0) rotate(45deg); }
  50%, 70% { transform: translateX(10px) rotate(45deg); }
  100% { transform: translateX(0) rotate(45deg); }
}
@keyframes ae-trail-loop {
  0%, 20%   { opacity: 0; transform: translateX(0) scale(.6); }
  38%       { opacity: .5; transform: translateX(5px) scale(1); }
  50%, 70%  { opacity: 0; transform: translateX(9px) scale(.4); }
  100%      { opacity: 0; transform: translateX(0) scale(.6); }
}
.ae-link.is-demo .ae-link__shaft { animation: ae-extend-shaft $duration $easing infinite; }
.ae-link.is-demo .ae-link__head { animation: ae-extend-head $duration $easing infinite; }
.ae-link.is-demo .ae-link__trail--1 { animation: ae-trail-loop $duration $ease-out infinite; }
.ae-link.is-demo .ae-link__trail--2 { animation: ae-trail-loop $duration $ease-out 60ms infinite; }

@media (prefers-reduced-motion: reduce) {
  .ae-link:hover .ae-link__shaft,
  .ae-link.is-demo .ae-link__shaft {
    animation: none !important;
    transition: none !important;
    transform: scaleX(1) !important;
  }
  .ae-link:hover .ae-link__head,
  .ae-link.is-demo .ae-link__head {
    animation: none !important;
    transition: none !important;
    transform: translateX(0) rotate(45deg) !important;
  }
  .ae-link__trail,
  .ae-link:hover .ae-link__trail,
  .ae-link.is-demo .ae-link__trail {
    animation: none !important;
    opacity: 0 !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);
}

.ae-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: #fff7e6;
  text-decoration: none;
  font: 600 16px/1 -apple-system, "Segoe UI", sans-serif;
}

.ae-link__arrow {
  position: relative;
  display: inline-flex;
  align-items: center;
  width: 26px;
  height: 12px;
}

.ae-link__shaft {
  position: absolute;
  left: 0;
  width: 16px;
  height: 2px;
  background: #fff7e6;
  transform-origin: left center;
  transform: scaleX(1);
  transition: transform 260ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

.ae-link__head {
  position: absolute;
  left: 10px;
  width: 8px;
  height: 8px;
  border-top: 2px solid #fff7e6;
  border-right: 2px solid #fff7e6;
  transform: translateX(0) rotate(45deg);
  transition: transform 260ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

.ae-link__trail {
  position: absolute;
  left: 10px;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: #fff7e6;
  opacity: 0;
}

.ae-link:hover .ae-link__shaft {
  transform: scaleX(1.8);
}

.ae-link:hover .ae-link__head {
  transform: translateX(10px) rotate(45deg);
}

@keyframes ae-trail-hover {
  0% {
    opacity: 0;
    transform: translateX(0) scale(0.6);
  }
  45% {
    opacity: 0.5;
    transform: translateX(5px) scale(1);
  }
  100% {
    opacity: 0;
    transform: translateX(9px) scale(0.4);
  }
}
.ae-link:hover .ae-link__trail--1 {
  animation: ae-trail-hover 420ms ease-out forwards;
}

.ae-link:hover .ae-link__trail--2 {
  animation: ae-trail-hover 420ms ease-out 70ms forwards;
}

@keyframes ae-extend-shaft {
  0%, 20% {
    transform: scaleX(1);
  }
  50%, 70% {
    transform: scaleX(1.8);
  }
  100% {
    transform: scaleX(1);
  }
}
@keyframes ae-extend-head {
  0%, 20% {
    transform: translateX(0) rotate(45deg);
  }
  50%, 70% {
    transform: translateX(10px) rotate(45deg);
  }
  100% {
    transform: translateX(0) rotate(45deg);
  }
}
@keyframes ae-trail-loop {
  0%, 20% {
    opacity: 0;
    transform: translateX(0) scale(0.6);
  }
  38% {
    opacity: 0.5;
    transform: translateX(5px) scale(1);
  }
  50%, 70% {
    opacity: 0;
    transform: translateX(9px) scale(0.4);
  }
  100% {
    opacity: 0;
    transform: translateX(0) scale(0.6);
  }
}
.ae-link.is-demo .ae-link__shaft {
  animation: ae-extend-shaft 2s cubic-bezier(0.34, 1.56, 0.64, 1) infinite;
}

.ae-link.is-demo .ae-link__head {
  animation: ae-extend-head 2s cubic-bezier(0.34, 1.56, 0.64, 1) infinite;
}

.ae-link.is-demo .ae-link__trail--1 {
  animation: ae-trail-loop 2s ease-out infinite;
}

.ae-link.is-demo .ae-link__trail--2 {
  animation: ae-trail-loop 2s ease-out 60ms infinite;
}

@media (prefers-reduced-motion: reduce) {
  .ae-link:hover .ae-link__shaft,
  .ae-link.is-demo .ae-link__shaft {
    animation: none !important;
    transition: none !important;
    transform: scaleX(1) !important;
  }
  .ae-link:hover .ae-link__head,
  .ae-link.is-demo .ae-link__head {
    animation: none !important;
    transition: none !important;
    transform: translateX(0) rotate(45deg) !important;
  }
  .ae-link__trail,
  .ae-link:hover .ae-link__trail,
  .ae-link.is-demo .ae-link__trail {
    animation: none !important;
    opacity: 0 !important;
  }
}

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

export interface ExtendingArrowProps {
  duration?: string;
  easing?: string;
  color?: string;
}

// 실사용: :hover 만으로 동작한다. is-demo 강제 루프는 넣지 않는다 (블로그공장 react 컨벤션)
export default function ExtendingArrow({
  duration = "260ms",
  easing = "cubic-bezier(.34, 1.56, .64, 1)",
  color = "#fff7e6",
}: ExtendingArrowProps) {
  const style = { "--duration": duration, "--easing": easing, "--color": color } as CSSProperties;
  return (
    <a className={styles.link} href="#" style={style}>
      <span>Learn more</span>
      <span className={styles.arrow}>
        <span className={styles.shaft} />
        <span className={styles.head} />
        <span className={`${styles.trail} ${styles.trail1}`} aria-hidden="true" />
        <span className={`${styles.trail} ${styles.trail2}`} aria-hidden="true" />
      </span>
    </a>
  );
}