Function moveKeyframeInScript

packages/parsers/src/gsapParser.ts:2333–2381

(
  script: string,
  animationId: string,
  fromPercentage: number,
  toPercentage: number,
)

 * the move resolves onto the same keyframe. Acorn twin: moveKeyframeInScript.
 */
export function moveKeyframeInScript(
  script: string,
  animationId: string,
  fromPercentage: number,
  toPercentage: number,
): string {
  const loc = locateAnimationWithFallback(script, animationId);
  if (!loc) return script;
  // Array-form keyframes can't host an arbitrary destination percentage —
  // normalize to object form in place first (mirrors addKeyframeToScript).
  const kfNode =
    findKeyframesObjectNode(loc.target.call.varsArg) ??
    convertArrayKeyframesToObjectNode(loc.target.call.varsArg);
  if (!kfNode) return script;

  const match = findKeyframePropByPct(kfNode, fromPercentage);
  if (!match) return script;
  // No-op ONLY for a negligible move (matches the drag's NOOP_EPSILON). The old
  // `collision.prop === match.prop` guard dropped EVERY sub-PCT_TOLERANCE (2%)
  // retime, because findKeyframePropByPct resolves the destination back onto the
  // from-keyframe — so a deliberate 1% drag committed nothing. Acorn twin too.
  if (Math.abs(fromPercentage - toPercentage) < MOVE_NOOP_EPSILON_PCT) return script;
  // A destination keyframe is only a real collision (overwrite) when it's a
  // DIFFERENT keyframe; resolving back onto the from-keyframe is not.
  const dest = findKeyframePropByPct(kfNode, toPercentage);
  const collision = dest && dest.prop !== match.prop ? dest : null;

  // Reuse each keyframe's value node verbatim (preserves properties +
  // per-keyframe ease + _auto). Drop the moved keyframe (and any destination
  // keyframe it overwrites), re-key the moved value to toPercentage, then re-sort.
  const movedValue = match.prop.value;
  const entries: Array<{ pct: number; value: AstNode }> = [];
  for (const prop of filterPercentageProps(kfNode)) {
    if (prop === match.prop) continue;
    if (collision && prop === collision.prop) continue;
    const pct = percentageFromKey(propKeyName(prop) ?? "");
    if (Number.isNaN(pct)) continue;
    entries.push({ pct, value: prop.value });
  }
  entries.push({ pct: toPercentage, value: movedValue });
  entries.sort((a, b) => a.pct - b.pct);

  kfNode.properties = entries.map((e) => {
    const p = parseExpr(`{ ${JSON.stringify(`${e.pct}%`)}: {} }`).properties[0];
    p.value = e.value;
    return p;
  });
  return recast.print(loc.parsed.ast).code;
}

/**
 * Resize a keyframed tween's window (boundary drag-to-retime): set the tween's