// ==UserScript==
// @name         anti-rickroll
// @namespace    http://tampermonkey.net/
// @version      3.1
// @description  静默并行扫描，修复检测完成后不放行的问题
// @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 MAX_CONCURRENT = 10;
    const cache = new Map(); // URL -> {isRick: bool, status: 'pending'|'done'}
    const queue = [];
    let activeRequests = 0;

    GM_addStyle(`
        #rick-guard-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.85); z-index: 2147483647; display: flex; justify-content: center; align-items: center; backdrop-filter: blur(8px); }
        .rick-modal { background: #fff; padding: 30px; border-radius: 15px; width: 320px; text-align: center; border: 2px solid #ff4444; font-family: sans-serif; }
        .rick-btns { display: flex; gap: 10px; margin-top: 20px; }
        .rick-btn { flex: 1; padding: 12px; border-radius: 8px; cursor: pointer; border: none; font-weight: bold; }
        .btn-go { background: #ff4444; color: white; }
        .btn-cancel { background: #eee; }
    `);

    // 扫描控制核心
    function processQueue() {
        if (queue.length === 0 || activeRequests >= MAX_CONCURRENT) return;
        const url = queue.shift();
        activeRequests++;

        GM_xmlhttpRequest({
            method: "POST",
            url: API_ENDPOINT,
            headers: { "Content-Type": "application/json" },
            data: JSON.stringify({ url: url }),
            timeout: 6000,
            onload: (res) => {
                try {
                    const data = JSON.parse(res.responseText);
                    updateCache(url, !!data.isRickroll);
                } catch (e) { updateCache(url, false); }
                activeRequests--; processQueue();
            },
            onerror: () => { updateCache(url, false); activeRequests--; processQueue(); },
            ontimeout: () => { updateCache(url, false); activeRequests--; processQueue(); }
        });
    }

    function updateCache(url, result) {
        cache.set(url, { isRick: result, status: 'done' });
        // 触发一个自定义事件，通知正在等待的点击逻辑
        window.dispatchEvent(new CustomEvent('rick_checked_' + url, { detail: result }));
    }

    function scan() {
        document.querySelectorAll('a[href]').forEach(a => {
            const url = a.href;
            if (!url.startsWith('http') || cache.has(url)) return;
            
            cache.set(url, { isRick: false, status: 'pending' });
            queue.push(url);
            processQueue();
        });
    }

    // 点击拦截与等待逻辑
    window.addEventListener('click', function(e) {
        const a = e.target.closest('a');
        if (!a || !a.href || !a.href.startsWith('http')) return;
        if (a.dataset.rickVerified === '1') return; // 已人工放行

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

        // 情况1：已经在缓存里且判定为危险
        if (result && result.status === 'done' && result.isRick) {
            e.preventDefault();
            showWarning(a.href, a);
            return;
        }

        // 情况2：已经在缓存里且判定为安全
        if (result && result.status === 'done' && !result.isRick) {
            return; // 正常放行
        }

        // 情况3：正在检测中或尚未开始检测
        e.preventDefault();
        e.stopPropagation();

        // 临时锁定，避免重复弹窗
        if (a.dataset.rickWaiting === '1') return;
        a.dataset.rickWaiting = '1';

        // 监听检测完成的信号
        const checkHandler = (ev) => {
            const isRickroll = ev.detail;
            delete a.dataset.rickWaiting;
            if (isRickroll) {
                showWarning(a.href, a);
            } else {
                a.dataset.rickVerified = '1';
                a.click(); // 安全，重新触发点击
            }
        };
        
        // 如果完全没在队列里，手动推入
        if (!result) {
            cache.set(a.href, { isRick: false, status: 'pending' });
            queue.unshift(a.href); // 优先插队扫描
            processQueue();
        }

        window.addEventListener('rick_checked_' + a.href, checkHandler, { once: true });
    }, true);

    function showWarning(url, el) {
        const div = document.createElement('div');
        div.id = 'rick-guard-overlay';
        div.innerHTML = `
            <div class="rick-modal">
                <h2 style="color:#ff4444;margin:0">🚨 风险链接拦截</h2>
                <p style="color:#555;font-size:14px;margin-top:10px">该链接被识别为 Rickroll 或钓鱼网页。</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(div);
        document.getElementById('r-close').onclick = () => div.remove();
        document.getElementById('r-go').onclick = () => {
            div.remove();
            el.dataset.rickVerified = '1';
            window.location.href = url;
        };
    }

    setTimeout(scan, 1000);
    const observer = new MutationObserver(scan);
    observer.observe(document.body, { childList: true, subtree: true });
})();