import { clamp } from "../slider-utils/clamp.jsx";

/**
 * Sub-pixel tolerance around each edge. Scroll offsets within one pixel of
 * 0 or the maximum are treated as "at the edge" — browsers occasionally
 * report fractional offsets due to device-pixel rounding even when the
 * user perceives the content to be fully scrolled.
 */
export const SCROLL_EDGE_TOLERANCE_PX = 1;

/**
 * Maximum scroll offset available for the given scroll and client sizes.
 * Guards against negative values — when content is smaller than the
 * viewport, the max is 0, not a negative number.
 */
export function getMaxScrollOffset(scrollSize, clientSize) {
  return Math.max(0, scrollSize - clientSize);
}

/**
 * Clamps `value` into `[0, max]` and snaps to whichever edge is within
 * {@link SCROLL_EDGE_TOLERANCE_PX}. When both edges are within tolerance
 * (i.e. `max <= SCROLL_EDGE_TOLERANCE_PX`) the closer edge wins, with ties
 * going to the start.
 */
export function normalizeScrollOffset(value, max) {
  if (max <= 0) {
    return 0;
  }
  const clamped = clamp(value, 0, max);
  const startDistance = clamped;
  const endDistance = max - clamped;
  const withinStartTolerance = startDistance <= SCROLL_EDGE_TOLERANCE_PX;
  const withinEndTolerance = endDistance <= SCROLL_EDGE_TOLERANCE_PX;
  if (withinStartTolerance && withinEndTolerance) {
    return startDistance <= endDistance ? 0 : max;
  }
  if (withinStartTolerance) {
    return 0;
  }
  if (withinEndTolerance) {
    return max;
  }
  return clamped;
}
//# sourceMappingURL=scroll-edges.jsx.map