/**
 * useScroll React custom hook
 * Usage:
 *    const { x, y, direction } = useScroll();
 */

import { useState, useEffect } from "react";

export default function useScroll() {
  if(!process.browser) return {x: null, y: null, direction: null}
  let rect = document.body.getBoundingClientRect()
  const [scrollData, setScrollData] = useState({
      lastScrollTop: 0,
      bodyOffset: rect,
      scrollX: rect.left,
      scrollY: -rect.top,
      scrollDirection: null
  })

  const debounce = (func, wait = 10, immediate = true) => {
    let timeout
    return (...args) => {
      let context = this
      let later = () => {
        timeout = null
        if (!immediate) func.apply(context, args)
      }
      let callNow = immediate && !timeout
      clearTimeout(timeout)
      timeout = setTimeout(later, wait)
      if (callNow) func.apply(context, args)
    }
  }

  const listener = () => {
    rect = document.body.getBoundingClientRect()
    const lastScrollTop = scrollData.lastScrollTop
    setScrollData({
        lastScrollTop: -rect.top, 
        bodyOffset: rect,
        scrollX: rect.left,
        scrollY: -rect.top,
        scrollDirection: lastScrollTop > -rect.top ? 'up' : 'down'
    })
  }

  const handler = debounce(listener, 50, true)

  useEffect(() => {
    window.addEventListener("scroll", handler);
    return () => {
      window.removeEventListener("scroll", handler);
    }
  });

  return {
    x: scrollData.scrollX,
    y: scrollData.scrollY,
    direction: scrollData.scrollDirection
  }
}