export default function useScroll(element: string) {

  let isScrolledToBottom: boolean;

  // Set the initial scroll position.
  const setScroll = (smooth: boolean) => {
    const view = document.getElementById(element)

    if (view) {
      view.scrollTo({
        top: view.scrollHeight - view.clientHeight,
        behavior: (smooth) ? 'smooth' : 'auto' 
      });
    }
  }

  // Update isScrolledToBottom
  const updateScrollRef = () => {
    const view = document.getElementById(element)

    if (view) {
      isScrolledToBottom = view.scrollHeight - view.clientHeight <= view.scrollTop + 1
    }

  }

  // Adjust scroll after we add content to the messenger.
  const adjustScroll = () => {
    const view = document.getElementById(element)

    if (view) {
      if (isScrolledToBottom) {
        view.scrollTo({
          top: view.scrollHeight - view.clientHeight,
          behavior: 'smooth'
        });
      }
    }

  }

  return {
    updateScrollRef,
    adjustScroll, 
    setScroll,
  }
  
}