import React from "react";

/**
 * Window scroll position
 */
export interface IScrollPos {
  x: number;
  y: number;
}

/**
 * Detect window scroll
 * @returns Scroll location
 */
export const useWindowScroll = () => {
  // State
  const [pos, setPos] = React.useState<IScrollPos>({
    x: window.scrollX,
    y: window.scrollY
  });

  React.useEffect(() => {
    let ticking = false;
    let lastPos: IScrollPos;
    let requestAnimationFrameSeed = 0;

    const scrollHandler = () => {
      lastPos = {
        x: window.scrollX,
        y: window.scrollY
      };

      if (!ticking) {
        requestAnimationFrameSeed = window.requestAnimationFrame(() => {
          ticking = false;
          requestAnimationFrameSeed = 0;

          if (lastPos.x != pos.x || lastPos.y != pos.y) {
            setPos(lastPos);
          }
        });
        ticking = true;
      }
    };

    window.addEventListener("scroll", scrollHandler, {
      passive: true,
      capture: false
    });

    return () => {
      // Cancel animation frame
      if (requestAnimationFrameSeed > 0)
        window.cancelAnimationFrame(requestAnimationFrameSeed);

      // Remove scroll event
      window.removeEventListener("scroll", scrollHandler);
    };
  }, []);

  // Return
  return pos;
};