import useViewportSize from '../useViewportSize';

/**
 * Returns the maximum space available above or below the source trigger
 * @param triggerRef The `ref` object attached to the source trigger
 * @param margin The space around the trigger
 */
const useAvailableSpace = (
  triggerRef?: React.RefObject<HTMLElement>,
  margin = 8,
) => {
  const viewportSize = useViewportSize();

  if (viewportSize && triggerRef && triggerRef.current) {
    // Get the top & bottom coordinates of the trigger
    const { top: triggerTop, bottom: triggerBottom } =
      triggerRef.current.getBoundingClientRect();

    // Find out how much space is available above or below the trigger
    const safeSpace = Math.max(viewportSize.height - triggerBottom, triggerTop);

    // Return to fill the space available
    return safeSpace - margin;
  }
};

export default useAvailableSpace;