// ==UserScript==
// @name         抖音直播自动下翻 (可见性检测版)
// @namespace    http://tampermonkey.net/
// @version      1.4
// @description  只有当“直播中”标签在屏幕上可见时，才触发自动翻页
// @author       Gemini
// @match        *://*.douyin.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // --- 1. 创建 UI 指示器 ---
    const container = document.createElement('div');
    container.style.cssText = 'position:fixed; bottom:60px; left:30px; display:flex; align-items:center; z-index:10001; pointer-events:none; font-family:sans-serif;';

    const dot = document.createElement('div');
    dot.style.cssText = 'width:12px; height:12px; background-color:#00ff00; border-radius:50%; box-shadow:0 0 10px #00ff00; transition:all 0.3s;';

    const label = document.createElement('div');
    label.innerText = '当前是直播间';
    label.style.cssText = 'margin-left:10px; background:rgba(0,0,0,0.7); color:#00ff00; padding:4px 12px; border-radius:4px; font-size:12px; opacity:0; transition:0.3s; border:1px solid #00ff00;';

    container.appendChild(dot);
    container.appendChild(label);
    document.body.appendChild(container);

    let hasTriggeredForThisVideo = false;

    // --- 2. 核心逻辑：判断元素是否真正可见 ---
    const isElementVisible = (el) => {
        if (!el) return false;
        const rect = el.getBoundingClientRect();
        // 1. 检查是否在视口范围内
        // 2. 检查元素大小是否大于0（排除 display:none）
        return (
            rect.top >= 0 &&
            rect.left >= 0 &&
            rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
            rect.right <= (window.innerWidth || document.documentElement.clientWidth) &&
            rect.width > 0 &&
            rect.height > 0
        );
    };

    const pressArrowDown = () => {
        hasTriggeredForThisVideo = false;
        const options = { key: 'ArrowDown', keyCode: 40, code: 'ArrowDown', which: 40, bubbles: true };
        window.dispatchEvent(new KeyboardEvent('keydown', options));
        document.dispatchEvent(new KeyboardEvent('keydown', options));
        console.log('🚀 元素已可见，执行翻页');
    };

    const runDetection = () => {
        // 使用 XPath 寻找目标元素
        const xpath = "//div[contains(@class, 'semi-tag-content') and text()='直播中']";
        const element = document.evaluate(xpath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;

        // 如果元素存在 且 真正出现在屏幕上
        if (element && isElementVisible(element)) {
            // UI 变色并显示文字
            label.style.opacity = '1';
            dot.style.backgroundColor = '#ff4d4f';
            dot.style.boxShadow = '0 0 15px #ff4d4f';

            if (!hasTriggeredForThisVideo) {
                hasTriggeredForThisVideo = true;
                console.log( "检测到直播,执行按键翻页" );
                // 发现可见直播，延迟 800ms 翻页，给人一点反应时间
                setTimeout(pressArrowDown, 100);
            }
        } else {
            // 恢复 UI 状态
            label.style.opacity = '0';
            dot.style.backgroundColor = '#00ff00';
            dot.style.boxShadow = '0 0 10px #00ff00';

            // 如果连元素都没了，说明已经翻过去了，重置触发开关
            if (!element) {
                hasTriggeredForThisVideo = false;
            }
        }
    };

    // --- 3. 监听 ---
    // 抖音滑动比较快，我们结合 MutationObserver 和 高频轮询 确保不漏掉任何瞬间
    setInterval(runDetection, 300); // 每 300ms 检查一次可见性

    console.log('抖音直播可见性检测脚本注入成功');
})();