// ==UserScript==
// @name         web综合优化脚本（非首屏资源延迟加载与硬件加速）
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  优化非首屏CSS与图片延迟加载、硬件加速等功能。
// @author       KiwiFruit
// @match        *://*/*
// @grant        none
// @license MIT
// @downloadURL none
// ==/UserScript==
(function() {
    'use strict';

    // 引入 lozad.js 库
    const script = document.createElement('script');
    script.src = 'https://cdnjs.cloudflare.com/ajax/libs/lozad.js/1.15.0/lozad.min.js';
    document.head.appendChild(script);

    // 定义硬件加速相关的CSS类
    const hardwareAccelerationClass = 'enable-hardware-acceleration';
    const styleSheet = `
        .${hardwareAccelerationClass} {
            transform: translateZ(0);
            will-change: transform;
        }
    `;
    const styleElement = document.createElement('style');
    styleElement.type = 'text/css';
    styleElement.appendChild(document.createTextNode(styleSheet));
    document.head.appendChild(styleElement);

    // 判断元素是否在视口内
    function isElementInViewport(el) {
        const rect = el.getBoundingClientRect();
        return (
            rect.top >= 0 &&
            rect.left >= 0 &&
            rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
            rect.right <= (window.innerWidth || document.documentElement.clientWidth)
        );
    }

    // 启用硬件加速
    function enableHardwareAccelerationForVisibleElements() {
        const targetElements = document.querySelectorAll('.target-element');
        targetElements.forEach(element => {
            if (isElementInViewport(element)) {
                element.classList.add(hardwareAccelerationClass);
            } else {
                element.classList.remove(hardwareAccelerationClass);
            }
        });
    }

    // 页面加载完成后执行的初始化逻辑
    window.addEventListener('DOMContentLoaded', (event) => {
        // 初始化 lozad.js 图片懒加载
        script.onload = () => {
            const observer = lozad(); // lazy loads elements with default selector as '.lozad'
            observer.observe();
        };

        // 初始化非首屏CSS懒加载
        const lazyCssElements = document.querySelectorAll('.lazy-css');
        lazyCssElements.forEach(element => {
            const cssHref = element.getAttribute('data-lazy-css');
            if (cssHref) {
                const link = document.createElement('link');
                link.rel = 'stylesheet';
                link.href = cssHref;
                document.head.appendChild(link);
                element.parentElement.removeChild(element); // 移除占位符元素
            }
        });

        // 监听滚动事件（使用节流）
        window.addEventListener('scroll', () => {
            requestIdleCallback(enableHardwareAccelerationForVisibleElements);
        });

        // 监听点击事件（使用防抖）
        document.addEventListener('click', () => {
            requestIdleCallback(enableHardwareAccelerationForVisibleElements);
        });

        // 监听媒体播放事件
        document.addEventListener('play', enableHardwareAccelerationForVisibleElements, true);

        // 监听图片加载事件
        document.addEventListener('load', enableHardwareAccelerationForVisibleElements, true);

        // 初始化检查一次
        enableHardwareAccelerationForVisibleElements();

        // MutationObserver监听DOM变化，确保新添加的元素也能触发延迟加载和硬件加速
        const mutationObserver = new MutationObserver(mutations => {
            mutations.forEach(mutation => {
                mutation.addedNodes.forEach(node => {
                    if (node.nodeType === 1) {
                        if (node.tagName === 'IMG' && node.hasAttribute('data-src')) {
                            const observer = lozad(node); // lazy loads specific image
                            observer.observe();
                        } else if (node.classList.contains('lazy-css') && node.hasAttribute('data-lazy-css')) {
                            const cssHref = node.getAttribute('data-lazy-css');
                            const link = document.createElement('link');
                            link.rel = 'stylesheet';
                            link.href = cssHref;
                            document.head.appendChild(link);
                            node.parentElement.removeChild(node); // 移除占位符元素
                        } else if (node.matches('.target-element')) {
                            enableHardwareAccelerationForVisibleElements();
                        }
                    }
                });
            });
        });
        mutationObserver.observe(document.body, { childList: true, subtree: true });

        // ResizeObserver监控视口尺寸变化
        const resizeObserver = new ResizeObserver(() => {
            enableHardwareAccelerationForVisibleElements();
        });
        resizeObserver.observe(document.body);
    });
})();