Image Compare Slider

---
/**
 * ImageCompareSlider — Interactive dual-image split compare slider with draggable separator bar.
 * 
 * @param {string} beforeImage - URL of original / before image.
 * @param {string} afterImage - URL of modified / after image.
 * @param {string} beforeLabel - Label tag. Default is 'Before'.
 * @param {string} afterLabel - Label tag. Default is 'After'.
 * @param {number} initialPosition - Starting separator position (0 to 100). Default is 50.
 */
interface Props {
  beforeImage?: string;
  afterImage?: string;
  beforeLabel?: string;
  afterLabel?: string;
  initialPosition?: number;
}

const {
  beforeImage = 'https://images.unsplash.com/photo-1518770660439-4636190af475?w=800&auto=format&fit=crop&q=80',
  afterImage = 'https://images.unsplash.com/photo-1550751827-4bd374c3f58b?w=800&auto=format&fit=crop&q=80',
  beforeLabel = 'Before (Wireframe)',
  afterLabel = 'After (Production)',
  initialPosition = 50,
} = Astro.props;
---

<div class="img-compare" data-img-compare style={`--pos: ${initialPosition}%;`}>
  <div class="img-compare__layer img-compare__layer--after">
    <img src={afterImage} alt={afterLabel} loading="lazy" />
    <span class="img-compare__tag img-compare__tag--after">{afterLabel}</span>
  </div>

  <div class="img-compare__layer img-compare__layer--before" data-compare-before>
    <img src={beforeImage} alt={beforeLabel} loading="lazy" />
    <span class="img-compare__tag img-compare__tag--before">{beforeLabel}</span>
  </div>

  <div class="img-compare__handle" data-compare-handle aria-hidden="true">
    <div class="handle-line"></div>
    <div class="handle-button">
      <span>‹</span>
      <span>›</span>
    </div>
  </div>

  <input
    type="range"
    min="0"
    max="100"
    value={initialPosition}
    class="img-compare__range"
    aria-label="Drag to compare images"
    data-compare-range
  />
</div>

<style>
  .img-compare {
    position: relative;
    width: 100%;
    max-width: 600px;
    aspect-ratio: 16 / 10;
    overflow: hidden;
    border-radius: var(--r-xl, 20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 16px 40px rgba(0, 0, 0, 0.5);
    user-select: none;
    font-family: var(--font-sans, system-ui, sans-serif);
  }

  .img-compare__layer {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
  }

  .img-compare__layer img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    pointer-events: none;
  }

  .img-compare__layer--before {
    clip-path: polygon(0 0, var(--pos) 0, var(--pos) 100%, 0 100%);
  }

  .img-compare__tag {
    position: absolute;
    top: 14px;
    padding: 4px 10px;
    background: rgba(0, 0, 0, 0.65);
    backdrop-filter: blur(8px);
    color: #ffffff;
    font-size: 0.72rem;
    font-weight: 700;
    border-radius: var(--r-full, 9999px);
    border: 1px solid rgba(255, 255, 255, 0.15);
    pointer-events: none;
  }

  .img-compare__tag--before { left: 14px; }
  .img-compare__tag--after { right: 14px; }

  .img-compare__handle {
    position: absolute;
    top: 0;
    bottom: 0;
    left: var(--pos);
    transform: translateX(-50%);
    pointer-events: none;
    z-index: 5;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
  }

  .handle-line {
    width: 2px;
    height: 100%;
    background: #ffffff;
    box-shadow: 0 0 8px rgba(0, 0, 0, 0.8);
  }

  .handle-button {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: #ffffff;
    color: #050505;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    font-size: 0.95rem;
    font-weight: 900;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.6);
  }

  .img-compare__range {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: ew-resize;
    z-index: 10;
  }
</style>

<script>
  function setupImageCompare() {
    document.querySelectorAll('[data-img-compare]').forEach((comp) => {
      const range = comp.querySelector('[data-compare-range]') as HTMLInputElement;
      if (!range) return;

      range.addEventListener('input', () => {
        (comp as HTMLElement).style.setProperty('--pos', `${range.value}%`);
      });
    });
  }

  setupImageCompare();
  document.addEventListener('astro:page-load', setupImageCompare);
</script>