09Battery-shape gauge

<main class="stage">
  <div class="battery" role="progressbar" aria-valuemin="0" aria-valuemax="100" aria-valuenow="18" aria-label="Battery level">
    <div class="battery__cell is-demo">
      <div class="battery__fill"></div>
    </div>
    <div class="battery__nub"></div>
  </div>
  <p class="cap">Battery level</p>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;                             // 100 → 낮음까지 소진되는 시간
$easing: linear;
$color: $subject-cream;                           // 가득 찼을 때 색

@include stage($stage-ink);

@property --percent {
  syntax: "<number>";
  inherits: false;
  initial-value: 100;
}

.battery { display: flex; align-items: center; }
.battery__cell {
  width: 70px;
  height: 32px;
  border: 3px solid rgba(255, 255, 255, .4);
  border-radius: 6px;
  padding: 3px;
  box-sizing: border-box;
  overflow: hidden;
}
.battery__nub { width: 4px; height: 14px; background: rgba(255, 255, 255, .4); border-radius: 0 3px 3px 0; }
.battery__fill {
  --percent: 100;
  height: 100%;
  border-radius: 2px;
  background: $color;
  transform-origin: left center; // 규칙8: 좌변서 차오름
  transform: scaleX(calc(var(--percent) / 100));
  animation: drain $duration $easing infinite;
}
// 남은 양이 줄수록 색이 임계값마다 바뀐다 (초록 대신 브랜드 색 → 경고색, 토큰 밖 hex 를 새로 쓰지 않는다)
@keyframes drain {
  0%   { --percent: 100; background: #{$color}; }
  55%  { --percent: 35;  background: #{$stage-yellow}; }
  100% { --percent: 8;   background: #{$error}; }
}
// 잔량이 낮아지는 마지막 구간에만 테두리가 살짝 깜빡인다
.battery__cell.is-demo { animation: pulse .6s ease-in-out infinite; animation-delay: 1.4s; }
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: .55; } }

.cap {
  margin: 14px 0 0;
  color: rgba(255, 255, 255, .75);
  font: 600 clamp(12px, 3.2vw, 14px)/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  .battery__fill { animation: none; --percent: 18; background: #{$error}; }
  .battery__cell.is-demo { animation: none; }
}

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);
}

@property --percent {
  syntax: "<number>";
  inherits: false;
  initial-value: 100;
}
.battery {
  display: flex;
  align-items: center;
}

.battery__cell {
  width: 70px;
  height: 32px;
  border: 3px solid rgba(255, 255, 255, 0.4);
  border-radius: 6px;
  padding: 3px;
  box-sizing: border-box;
  overflow: hidden;
}

.battery__nub {
  width: 4px;
  height: 14px;
  background: rgba(255, 255, 255, 0.4);
  border-radius: 0 3px 3px 0;
}

.battery__fill {
  --percent: 100;
  height: 100%;
  border-radius: 2px;
  background: #fff7e6;
  transform-origin: left center;
  transform: scaleX(calc(var(--percent) / 100));
  animation: drain 2s linear infinite;
}

@keyframes drain {
  0% {
    --percent: 100;
    background: #fff7e6;
  }
  55% {
    --percent: 35;
    background: #ffd23f;
  }
  100% {
    --percent: 8;
    background: #c2361a;
  }
}
.battery__cell.is-demo {
  animation: pulse 0.6s ease-in-out infinite;
  animation-delay: 1.4s;
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.55;
  }
}
.cap {
  margin: 14px 0 0;
  color: rgba(255, 255, 255, 0.75);
  font: 600 clamp(12px, 3.2vw, 14px)/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

@media (prefers-reduced-motion: reduce) {
  .battery__fill {
    animation: none;
    --percent: 18;
    background: #c2361a;
  }
  .battery__cell.is-demo {
    animation: none;
  }
}

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

export type BatteryGaugeProps = {
  /** 0~100 */
  percent: number;
  duration?: number;
  easing?: string;
  colorFull?: string;
  colorMid?: string;
  colorLow?: string;
  label?: string;
};

type Vars = CSSProperties & {
  "--duration"?: string;
  "--easing"?: string;
  "--percent"?: number;
  "--fill"?: string;
};

export default function BatteryGauge({
  percent,
  duration = 600,
  easing = "linear",
  colorFull = "#fff7e6",
  colorMid = "#ffd23f",
  colorLow = "#c2361a",
  label,
}: BatteryGaugeProps) {
  const p = Math.max(0, Math.min(100, percent));
  const fill = p > 55 ? colorFull : p > 20 ? colorMid : colorLow;
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--percent": p, "--fill": fill };

  return (
    <div
      className={p <= 15 ? `${styles.battery} ${styles.low}` : styles.battery}
      style={vars}
      role="progressbar"
      aria-valuemin={0}
      aria-valuemax={100}
      aria-valuenow={p}
      aria-label={label}
    >
      <div className={styles.cell}>
        <div className={styles.fill} />
      </div>
      <div className={styles.nub} />
    </div>
  );
}