import React from "react";

export default function useClickOutside(onClickOutside, exempt = []) {
  const container = React.useRef(null);
  const mouseDownTargetIsOutside = React.useRef(false);

  React.useEffect(() => {
    /* if the click event doesnt start outside of the element then we want to ignore it */
    /* imagine if someone clicked while swiping the cursor, if it started inside, then they probably */
    /* wouldn't expect mouseup to fire like it was outside */
    function onMouseDown(event) {
      /* If the target is inside, then don't fire click outside handler */
      if (container.current && container.current.contains(event.target)) {
        mouseDownTargetIsOutside.current = false;
        return;
      }

      mouseDownTargetIsOutside.current = true;
    }

    function onMouseUp(event) {
      /* If both targets weren't outside then we can bail early */
      const mouseUpTargetIsOutside =
        !container.current || !container.current.contains(event.target);
      if (!mouseDownTargetIsOutside.current || !mouseUpTargetIsOutside) {
        return;
      }

      /* exempt is an array of strings (css selectors) or html elements */
      /* Here we figure out if the target matches either, or is nested inside an exempt element */
      const targetIsExempt = exempt.some(selectorOrElement => {
        if (typeof selectorOrElement === "string") {
          return Boolean(event.target.closest(selectorOrElement));
        } else if (
          selectorOrElement instanceof HTMLElement ||
          selectorOrElement.current instanceof HTMLElement
        ) {
          const element = selectorOrElement.current || selectorOrElement;
          return event.target === element || element.contains(event.target);
        }

        return false;
      });

      if (targetIsExempt) {
        return;
      }

      onClickOutside(event, container);
    }

    window.addEventListener("mousedown", onMouseDown, true);
    window.addEventListener("mouseup", onMouseUp, true);

    return () => {
      window.removeEventListener("mousedown", onMouseDown, true);
      window.removeEventListener("mouseup", onMouseUp, true);
    };
  });

  return container;
}