// ==UserScript==
// @name         anti-rickroll
// @namespace    http://tampermonkey.net/
// @version      2.0
// @description  静默扫描页面链接，预先缓存检测结果，点击瞬发警告
// @author       dext
// @match        *://*/*
// @grant        GM_xmlhttpRequest
// @grant        GM_addStyle
// @connect      anti-rickroll.dext.top
// @run-at       document-idle
// @downloadURL none
// ==/UserScript==

(function() {
    'use strict';

    const API_ENDPOINT = "https://anti-rickroll.dext.top";
    const cache = new Map(); // 缓存：URL -> isRickroll (true/false)
    const scanning = new Set(); // 正在扫描中的URL，避免重复请求

    // 极简弹窗样式
    GM_addStyle(`
        #rick-guard-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.8); z-index: 2147483647; display: flex; justify-content: center; align-items: center; backdrop-filter: blur(5px); }
        .rick-modal { background: #fff; padding: 30px; border-radius: 12px; width: 320px; text-align: center; font-family: sans-serif; }
        .rick-btns { display: flex; gap: 10px; margin-top: 20px; }
        .rick-btn { flex: 1; padding: 10px; border-radius: 6px; cursor: pointer; border: none; font-weight: bold; }
        .btn-go { background: #ff4444; color: white; }
        .btn-cancel { background: #f0f0f0; }
    `);

    // 核心：扫描页面上的链接
    function scanLinks() {
        const links = Array.from(document.querySelectorAll('a[href]'));
        links.forEach(a => {
            const url = a.href;
            // 过滤掉非http、锚点、已处理过的
            if (!url.startsWith('http') || cache.has(url) || scanning.has(url)) return;

            // 过滤常见的大型信任网站，减少 API 压力
            const domain = new URL(url).hostname;
            if (domain.includes('google.com') || domain.includes('baidu.com') || domain.includes('github.com')) {
                cache.set(url, false);
                return;
            }

            scanning.add(url);
            
            GM_xmlhttpRequest({
                method: "POST",
                url: API_ENDPOINT,
                headers: { "Content-Type": "application/json" },
                data: JSON.stringify({ url: url }),
                onload: function(res) {
                    try {
                        const data = JSON.parse(res.responseText);
                        cache.set(url, data.isRickroll);
                        // 如果确定是诈骗，可以给链接加个淡淡的红边提醒（可选）
                        // if(data.isRickroll) a.style.outline = "1px dashed rgba(255,0,0,0.5)";
                    } catch (e) {}
                    scanning.delete(url);
                },
                onerror: () => scanning.delete(url)
            });
        });
    }

    // 初始扫描
    setTimeout(scanLinks, 1000);

    // 监听动态加载的内容（如瀑布流）
    const observer = new MutationObserver(scanLinks);
    observer.observe(document.body, { childList: true, subtree: true });

    // 点击拦截逻辑
    window.addEventListener('click', function(e) {
        const a = e.target.closest('a');
        if (!a || !a.href) return;

        const isRick = cache.get(a.href);

        // 如果缓存里确认是 Rickroll
        if (isRick === true) {
            e.preventDefault();
            e.stopPropagation();
            showWarning(a.href, a);
            return;
        }

        // 如果还没检测完 (isRick 为 undefined)，则放行，或者你可以选择拦截等待
        // 这里选择直接放行以保证用户体验，因为大部分链接是安全的
    }, true);

    function showWarning(url, originalElement) {
        const overlay = document.createElement('div');
        overlay.id = 'rick-guard-overlay';
        overlay.innerHTML = `
            <div class="rick-modal">
                <h2 style="color:#ff4444;margin:0">诈骗链接警告</h2>
                <p style="color:#666">该链接经 AI 识别为 Rickroll 或钓鱼网页，是否继续访问？</p>
                <div class="rick-btns">
                    <button class="rick-btn btn-cancel" id="r-close">取消</button>
                    <button class="rick-btn btn-go" id="r-go">继续访问</button>
                </div>
            </div>
        `;
        document.body.appendChild(overlay);
        document.getElementById('r-close').onclick = () => overlay.remove();
        document.getElementById('r-go').onclick = () => {
            overlay.remove();
            cache.set(url, false); // 暂时标记为安全以允许跳转
            window.location.href = url;
        };
    }
})();