import { closest } from "./DOM";

export function findScrollableParent(sourceEl: Element, horizontal: boolean = false): HTMLElement | null {
   if (!sourceEl) return null;
   let scrollParent = closest(sourceEl, (el) => {
      if (el.nodeType != Node.ELEMENT_NODE) return false;
      if (!horizontal && el.clientHeight >= el.scrollHeight) return false;
      if (horizontal && el.clientWidth >= el.scrollWidth) return false;
      let overflow = getComputedStyle(el).getPropertyValue(horizontal ? "overflow-x" : "overflow-y");
      return overflow == "auto" || overflow == "scroll";
   }) as HTMLElement;
   return (
      scrollParent || (sourceEl.ownerDocument.scrollingElement as HTMLElement) || sourceEl.ownerDocument.documentElement
   );
}