export interface LazyOptions {
    error?: string;
    loading?: string;
    observerOptions?: IntersectionObserverInit;
    log?: boolean;
}

export interface ValueFormatterObject {
    src: string;
    error?: string;
    loading?: string;
}

export default class Lazy {
    lazyActive: boolean;
    options: LazyOptions;

    _images = new WeakMap();

    constructor(flag = true, options: LazyOptions);

    config(options = {}): void;

    // mount
    mount(
        el: HTMLImageElement,
        binding: string | ValueFormatterObject,
        callback: () => void
    ): void;

    // unmount
    unmount(el: HTMLElement): void;

    resize(el: HTMLElement, callback: () => void): void;

    /**
     * 设置img的src
     * @param {*} el - img
     * @param {*} src - 原图
     * @param {*} error - 错误图片
     * @param {*} callback - 完成的回调函数，通知组件刷新布局
     * @returns
     */
    _setImageSrc(
        el: HTMLImageElement,
        src: string,
        callback: () => void,
        error?: string
    ): void;

    _isOpenLazy(): boolean;

    /**
     * 添加img和对应的observer到weakMap中
     * 开启监听
     * 当出现在可视区域后取消监听
     * @param {*} el - img
     * @param {*} src - 图片
     * @param {*} error - 错误图片
     * @param {*} callback - 完成的回调函数，通知组件刷新布局
     */
    _initIntersectionObserver(
        el: HTMLImageElement,
        src: string,
        callback: () => void,
        error?: string
    ): void;

    // 格式化参数
    _valueFormatter(value: ValueFormatterObject | string): ValueFormatterObject;

    // 日志
    _log(callback: () => void): void;

    // 在map中获取对应img的observer事件
    _realObserver(el: HTMLElement): IntersectionObserver | undefined;
}