/*
fork from:
https://github.com/ElemeFE/element
*/

import ResizeObserver from "resize-observer-polyfill";

/* istanbul ignore next */
const resizeHandler = function (entries) {
    for (let entry of entries) {
        const listeners = entry.target.__resizeListeners__ || [];
        if (listeners.length) {
            listeners.forEach((fn) => {
                fn(entry.contentRect);
            });
        }
    }
};

/* istanbul ignore next */
export const addResizeListener = function (element, fn) {
    if (!element.__resizeListeners__) {
        element.__resizeListeners__ = [];
        element.__ro__ = new ResizeObserver(resizeHandler);
        element.__ro__.observe(element);
    }
    element.__resizeListeners__.push(fn);
};

/* istanbul ignore next */
export const removeResizeListener = function (element, fn) {
    if (!element || !element.__resizeListeners__) return;
    element.__resizeListeners__.splice(
        element.__resizeListeners__.indexOf(fn),
        1,
    );
    if (!element.__resizeListeners__.length) {
        element.__ro__.disconnect();
    }
};
