06키보드 재정렬 — Alt+화살표로 배열 인덱스를 옮기고 aria-live 로 알리는 계산

<main class="stage">
<div class="ka">
  <p class="ka__hint">Alt+화살표로 인덱스를 옮기고 그 결과를 화면 낭독 영역에 알립니다</p>
  <ul class="ka__list" id="kaList" role="listbox" aria-orientation="vertical" aria-describedby="kaHelp">
    <li class="ka__row" data-id="0" role="option" tabindex="0" aria-selected="false"><span class="ka__txt">메시지</span></li>
    <li class="ka__row" data-id="1" role="option" tabindex="0" aria-selected="false"><span class="ka__txt">사진</span></li>
    <li class="ka__row" data-id="2" role="option" tabindex="0" aria-selected="false"><span class="ka__txt">메모</span></li>
    <li class="ka__row" data-id="3" role="option" tabindex="0" aria-selected="false"><span class="ka__txt">음악</span></li>
  </ul>
  <span id="kaHelp" class="ka__sr">Alt+↑↓ 로 행을 옮깁니다</span>
  <p class="ka__meta"><b class="ka__state" id="kaState">행 재정렬</b><span class="ka__unit" id="kaUnit">Alt+↑↓ 로 행을 옮깁니다</span></p>
  <p class="ka__live" id="kaLive" aria-live="polite"></p>
</div>
</main>

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

$duration: 220ms;
$easing: cubic-bezier(.2,.8,.2,1);
$color: $subject-ink;

@include stage($stage-yellow);

.ka {
  width: 100%;
  max-width: 340px;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}

.ka__hint {
  margin: 0;
  padding: 0 $sp-1;
  font-weight: 400;
  font-size: 11px;
  line-height: 1.4;
  color: $subject-ink;
}

.ka__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: $sp-1;
  overflow-y: auto;
}

.ka__row {
  padding: $sp-2;
  border-radius: $r-sm;
  background: $subject-cream;
  color: $subject-ink;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.3;
  box-shadow: $shadow-press;
  outline: none;
}

.ka__row:focus-visible {
  box-shadow: 0 0 0 2px $subject-blue-deep, $shadow-press;
}

.ka__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
}

.ka__meta {
  margin: 0;
  padding: 0 $sp-1;
  display: flex;
  align-items: baseline;
  gap: $sp-1;
}

.ka__state {
  font-weight: 700;
  font-size: 12px;
  color: $subject-ink;
}

.ka__unit {
  font-weight: 400;
  font-size: 11px;
  color: rgba($subject-ink, .72);
}

.ka__live {
  margin: 0;
  padding: 0 $sp-1;
  font-weight: 700;
  font-size: 11px;
  color: $color;
  min-height: 14px;
}

@media (max-width: 340px) {
  .ka { max-width: 260px; gap: $sp-1; }
  .ka__hint { font-size: 10px; }
  .ka__row { font-size: 11px; padding: $sp-1; }
  .ka__list { max-height: 84px; }
  .ka__live { min-height: 12px; font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  .ka__row {
    transition: none !important;
    transform: 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);
}

.ka {
  width: 100%;
  max-width: 340px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.ka__hint {
  margin: 0;
  padding: 0 4px;
  font-weight: 400;
  font-size: 11px;
  line-height: 1.4;
  color: #17141a;
}

.ka__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}

.ka__row {
  padding: 8px;
  border-radius: 8px;
  background: #fff7e6;
  color: #17141a;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.3;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  outline: none;
}

.ka__row:focus-visible {
  box-shadow: 0 0 0 2px #0a4fe8, 0 6px 12px rgba(23, 20, 26, 0.32);
}

.ka__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
}

.ka__meta {
  margin: 0;
  padding: 0 4px;
  display: flex;
  align-items: baseline;
  gap: 4px;
}

.ka__state {
  font-weight: 700;
  font-size: 12px;
  color: #17141a;
}

.ka__unit {
  font-weight: 400;
  font-size: 11px;
  color: rgba(23, 20, 26, 0.72);
}

.ka__live {
  margin: 0;
  padding: 0 4px;
  font-weight: 700;
  font-size: 11px;
  color: #17141a;
  min-height: 14px;
}

@media (max-width: 340px) {
  .ka {
    max-width: 260px;
    gap: 4px;
  }
  .ka__hint {
    font-size: 10px;
  }
  .ka__row {
    font-size: 11px;
    padding: 4px;
  }
  .ka__list {
    max-height: 84px;
  }
  .ka__live {
    min-height: 12px;
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ka__row {
    transition: none !important;
    transform: none !important;
  }
}

// 키보드 재정렬(06) — 포커스된 행에서 keydown 의 altKey && (ArrowUp|ArrowDown) 을 잡아 배열의
// 이웃 인덱스와 자리를 바꾼다. DOM 재배치는 FLIP 되돌림으로, 결과는 aria-live 영역에 알린다.
// 마우스 없는 사용자도 같은 handler 로 조작하므로 자동 시연도 이 함수를 그대로 부른다.
(function () {
  var list = document.getElementById('kaList');
  var liveEl = document.getElementById('kaLive');
  var stateEl = document.getElementById('kaState');
  if (!list || !liveEl || !stateEl) return;

  function rows() { return Array.prototype.slice.call(list.children); }

  function flipSwap(row, dir) {
    var arr = rows();
    var i = arr.indexOf(row);
    var j = i + dir;
    if (j < 0 || j >= arr.length) return i;
    var first = arr.map(function (r) { return r.getBoundingClientRect(); });
    if (dir > 0) list.insertBefore(arr[j], row);
    else list.insertBefore(row, arr[j]);
    arr.forEach(function (r, k) {
      var rr = r.getBoundingClientRect();
      var dy = first[k].top - rr.top;
      if (dy !== 0) {
        r.style.transition = 'none';
        r.style.transform = 'translateY(' + dy + 'px)';
        requestAnimationFrame(function () {
          r.style.transition = 'transform 220ms cubic-bezier(.2,.8,.2,1)';
          r.style.transform = 'translateY(0)';
        });
      }
    });
    return j;
  }

  function move(row, dir) {
    var j = flipSwap(row, dir);
    row.focus({ preventScroll: true });
    stateEl.textContent = '행 재정렬';
    liveEl.textContent = 'move ' + (j + 1) + '/' + rows().length;
  }

  function onKeydown(e) {
    if (!e.altKey) return;
    var row = e.target.closest('.ka__row');
    if (!row) return;
    if (e.key === 'ArrowUp') { stop(); e.preventDefault(); move(row, -1); }
    else if (e.key === 'ArrowDown') { stop(); e.preventDefault(); move(row, 1); }
  }
  list.addEventListener('keydown', onKeydown);

  // 자동 시연 — 실제 focus + move() 를 그대로 호출한다(포커스 이동도 실제로 일어난다)
  var playing = true;
  function stop() { playing = false; }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  function loopOnce() {
    var row = list.children[1];
    if (!row) return;
    row.focus({ preventScroll: true });
    move(row, 1);
    setTimeout(function () {
      var r2 = list.children[2];
      if (r2) { r2.focus({ preventScroll: true }); move(r2, -1); }
    }, 480);
    setTimeout(function () {
      var r3 = list.children[1];
      if (r3) { r3.focus({ preventScroll: true }); move(r3, 1); }
    }, 980);
    setTimeout(function () {
      var r4 = list.children[2];
      if (r4) { r4.focus({ preventScroll: true }); move(r4, -1); }
    }, 1480);
  }

  if (reduce) {
    var r0 = list.children[1];
    if (r0) move(r0, 1);
  } else {
    loopOnce();
    setInterval(function () { if (playing) loopOnce(); }, 1500);
  }
})();

// DragKeyboardAlt — vanilla 판(run/336/demo/06-drag-keyboard-alt/index.html)
// 의 React 포트. 포커스된 행에서 keydown 의 altKey && (ArrowUp|ArrowDown) 을 잡아 배열의
// 이웃 인덱스와 자리를 바꾼다. DOM 재배치는 FLIP 되돌림으로, 결과는 aria-live 영역에 알린다.
// 마우스 없는 사용자도 같은 handler 로 조작하므로 자동 시연도 이 함수를 그대로 부른다.
import { useEffect, useRef } from "react";
import styles from "./DragKeyboardAlt.module.scss";

export type DragKeyboardAltProps = {
  duration?: string;
  easing?: string;
  color?: string;
};

const HINT = "Alt+화살표로 인덱스를 옮기고 그 결과를 화면 낭독 영역에 알립니다";
const HELP_TEXT = "Alt+↑↓ 로 행을 옮깁니다";
const ROW_TXT = ["메시지", "사진", "메모", "음악"];

export default function DragKeyboardAlt({
  duration = "220ms",
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#17141a"
}: DragKeyboardAltProps) {
  const listRef = useRef<HTMLUListElement | null>(null);
  const liveRef = useRef<HTMLElement | null>(null);
  const stateRef = useRef<HTMLElement | null>(null);

  useEffect(() => {
    const list = listRef.current;
    const liveEl = liveRef.current;
    const stateEl = stateRef.current;
    if (!list || !liveEl || !stateEl) return;

    function rows(): HTMLElement[] {
      return Array.prototype.slice.call(list!.children);
    }

    function flipSwap(row: HTMLElement, dir: number): number {
      const arr = rows();
      const i = arr.indexOf(row);
      const j = i + dir;
      if (j < 0 || j >= arr.length) return i;
      const first = arr.map((r) => r.getBoundingClientRect());
      if (dir > 0) list!.insertBefore(arr[j], row);
      else list!.insertBefore(row, arr[j]);
      arr.forEach((r, k) => {
        const rr = r.getBoundingClientRect();
        const dy = first[k].top - rr.top;
        if (dy !== 0) {
          r.style.transition = "none";
          r.style.transform = "translateY(" + dy + "px)";
          requestAnimationFrame(() => {
            r.style.transition = "transform " + duration + " " + easing;
            r.style.transform = "translateY(0)";
          });
        }
      });
      return j;
    }

    function move(row: HTMLElement, dir: number): void {
      const j = flipSwap(row, dir);
      row.focus({ preventScroll: true });
      stateEl!.textContent = "행 재정렬";
      liveEl!.textContent = "move " + (j + 1) + "/" + rows().length;
    }

    function onKeydown(e: KeyboardEvent): void {
      if (!e.altKey) return;
      const row = (e.target as HTMLElement).closest("." + styles.row) as HTMLElement | null;
      if (!row) return;
      if (e.key === "ArrowUp") {
        stop();
        e.preventDefault();
        move(row, -1);
      } else if (e.key === "ArrowDown") {
        stop();
        e.preventDefault();
        move(row, 1);
      }
    }
    list.addEventListener("keydown", onKeydown as EventListener);

    let playing = true;
    function stop(): void {
      playing = false;
    }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const timeouts: number[] = [];
    let intervalId = 0;

    function loopOnce(): void {
      const row = list!.children[1] as HTMLElement | undefined;
      if (!row) return;
      row.focus({ preventScroll: true });
      move(row, 1);
      timeouts.push(
        window.setTimeout(() => {
          const r2 = list!.children[2] as HTMLElement | undefined;
          if (r2) {
            r2.focus({ preventScroll: true });
            move(r2, -1);
          }
        }, 480)
      );
      timeouts.push(
        window.setTimeout(() => {
          const r3 = list!.children[1] as HTMLElement | undefined;
          if (r3) {
            r3.focus({ preventScroll: true });
            move(r3, 1);
          }
        }, 980)
      );
      timeouts.push(
        window.setTimeout(() => {
          const r4 = list!.children[2] as HTMLElement | undefined;
          if (r4) {
            r4.focus({ preventScroll: true });
            move(r4, -1);
          }
        }, 1480)
      );
    }

    if (reduce) {
      const r0 = list.children[1] as HTMLElement | undefined;
      if (r0) move(r0, 1);
    } else {
      loopOnce();
      intervalId = window.setInterval(() => {
        if (playing) loopOnce();
      }, 1500);
    }

    return () => {
      timeouts.forEach((t) => clearTimeout(t));
      if (intervalId) clearInterval(intervalId);
      list.removeEventListener("keydown", onKeydown as EventListener);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.ka}>
        <p className={styles.hint}>{HINT}</p>
        <ul className={styles.list} ref={listRef} role="listbox" aria-orientation="vertical" aria-describedby="kaHelpReact">
          {ROW_TXT.map((txt, i) => (
            <li key={i} className={styles.row} role="option" tabIndex={0} aria-selected="false">
              <span>{txt}</span>
            </li>
          ))}
        </ul>
        <span id="kaHelpReact" className={styles.sr}>{HELP_TEXT}</span>
        <p className={styles.meta}>
          <b className={styles.state} ref={stateRef} style={{ color }}>행 재정렬</b>
          <span className={styles.unit}>{HELP_TEXT}</span>
        </p>
        <p className={styles.live} ref={liveRef} aria-live="polite"></p>
      </div>
    </main>
  );
}