// ==UserScript==
// @name         维咔ACG增强
// @namespace    http://tampermonkey.net/
// @version      2.1
// @description  维咔ACG的每日签到、预览图增强、直链跳转、隐藏搜索结果的广告帖子
// @author       临渊
// @match        *://*.vikacg.com/*
// @match        *://*.vikacg.cc/*
// @match        *://*.vikacg.xyz/*
// @match        *://*.vikacg.net/*
// @match        *://*.vikacg.org/*
// @grant        GM_xmlhttpRequest
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_deleteValue
// @grant        GM_listValues
// @grant        GM_registerMenuCommand
// @grant        unsafeWindow
// @connect      *
// @run-at       document-start
// @license AGPL-3.0
// ==/UserScript==

/* ==UserConfig==
preview:
  count:
    title: 预览图片数
    description: 设置为 0 可关闭列表预览增强
    type: number
    default: 4
    min: 0
    max: 6
  concurrent:
    title: 预览请求并发
    description: 同时请求详情页图片的数量
    type: number
    default: 6
    min: 1
    max: 12
 ==/UserConfig== */

(function() {
    'use strict';
    const LOG_PREFIX = '[维咔ACG增强]';

    const urlMap = {};
    const SIGN_STATE_KEY = 'vikacgEnhanced.signState';
    const AUTH_HEADER_KEY = 'vikacgEnhanced.authorization';
    const AUTH_TTL_MS = 7 * 24 * 60 * 60 * 1000;
    const LOG_LEVEL_KEY = 'vikacgEnhanced.logLevel';
    const LOG_LEVELS = { debug: 10, log: 20, info: 20, warn: 30, error: 40, silent: 99 };
    const PREVIEW_CACHE_PREFIX = 'vikacgEnhanced.preview.v4.';
    const PREVIEW_COUNT_KEY = 'preview.count';
    const PREVIEW_CONCURRENT_KEY = 'preview.concurrent';
    const PREVIEW_CACHE_TTL_MS = 24 * 60 * 60 * 1000;
    const PREVIEW_DEFAULT_COUNT = 4;
    const PREVIEW_MAX_COUNT = 12;
    const PREVIEW_AUTH_RETRY_MAX = 8;
    const PREVIEW_AUTH_RETRY_DELAY_MS = 1000;
    const SIGN_LOCK_MS = 2 * 60 * 1000;
    const SIGN_MAX_DAILY = 2;
    const MAX_MAPPING_RETRY_WITHOUT_PROGRESS = 3;
    const RECOMMEND_HIDDEN_CLASS = 'vikacg-enhanced-recommend-hidden';
    const DEFAULT_RECOMMEND_KEYWORDS = ['推荐'];
    const RECOMMEND_KEYWORDS_KEY = 'recommend.keywords';
    let isLoading = false;
    let isSigning = false;
    let mappedPostId = null;
    let routePath = getRouteKey();
    let rawContentCache = { postId: null, content: '' };
    let mappingRetryTimer = null;
    let mappingRetryState = { postId: null, signature: '', attempts: 0, stopped: false };
    let previewRetryTimer = null;
    let previewFetchObserver = null;
    let previewPending = 0;
    let previewQueue = [];
    let previewScanLogState = { signature: '', time: 0 };
    let mutationObserver = null;
    let appStarted = false;
    debugLog('log', `${LOG_PREFIX} 脚本已加载`);

    // 通用工具和日志：日志会同时写入控制台与页面对象，方便在沙盒脚本里排查。
    function getPageWindow() {
        return typeof unsafeWindow !== 'undefined' ? unsafeWindow : window;
    }

    function serializeLogArg(arg) {
        if (arg instanceof Error) return `${arg.name}: ${arg.message}`;
        if (typeof arg === 'string') return arg;
        try {
            return JSON.parse(JSON.stringify(arg));
        } catch (e) {
            return String(arg);
        }
    }

    function getLogConsoleLevel() {
        const level = String(gmGet(LOG_LEVEL_KEY, 'warn') || 'warn').toLowerCase();
        return Object.prototype.hasOwnProperty.call(LOG_LEVELS, level) ? level : 'warn';
    }

    function debugLog(level, ...args) {
        const method = console[level] ? level : 'log';
        const consoleLevel = getLogConsoleLevel();
        const shouldPrint = LOG_LEVELS[method] >= LOG_LEVELS[consoleLevel];
        if (shouldPrint) {
            try {
                console[method](...args);
            } catch (e) {
                // 保持日志函数自身不影响主逻辑。
            }
        }

        try {
            const target = getPageWindow();
            const targetConsole = target.console;
            if (shouldPrint && targetConsole && targetConsole !== console && targetConsole[method]) {
                targetConsole[method](...args);
            }

            const logs = target.__vikacgEnhancedLogs || [];
            logs.push({
                time: new Date().toISOString(),
                level: method,
                args: args.map(serializeLogArg),
            });
            if (logs.length > 300) logs.splice(0, logs.length - 300);
            target.__vikacgEnhancedLogs = logs;
        } catch (e) {
            // 页面窗口不可写时忽略。
        }
    }

    function getPostId() {
        const match = window.location.pathname.match(/\/p\/(\d+)/);
        return match ? match[1] : null;
    }

    function getApiBase() {
        return window.location.origin;
    }

    function getRouteKey() {
        return `${window.location.pathname}${window.location.search}`;
    }

    function clearMappings() {
        Object.keys(urlMap).forEach(key => delete urlMap[key]);
        mappedPostId = null;
        rawContentCache = { postId: null, content: '' };
        resetMappingRetryState();
    }

    function ensureToastContainer() {
        let container = document.getElementById('vikacg-enhanced-toast');
        if (container) return container;

        if (!document.getElementById('vikacg-enhanced-toast-style')) {
            const style = document.createElement('style');
            style.id = 'vikacg-enhanced-toast-style';
            style.textContent = `
                #vikacg-enhanced-toast {
                    position: fixed;
                    top: 18px;
                    right: 18px;
                    z-index: 2147483647;
                    display: flex;
                    flex-direction: column;
                    gap: 10px;
                    max-width: min(360px, calc(100vw - 32px));
                    pointer-events: none;
                }
                .vikacg-enhanced-toast-item {
                    padding: 10px 12px;
                    border-radius: 8px;
                    color: #fff;
                    font-size: 14px;
                    line-height: 1.45;
                    box-shadow: 0 8px 24px rgba(0, 0, 0, .18);
                    pointer-events: auto;
                    opacity: .98;
                }
                .vikacg-enhanced-toast-success { background: #18a058; }
                .vikacg-enhanced-toast-info { background: #2080f0; }
                .vikacg-enhanced-toast-warning { background: #f0a020; }
                .vikacg-enhanced-toast-error { background: #d03050; }
            `;
            document.head.appendChild(style);
        }

        container = document.createElement('div');
        container.id = 'vikacg-enhanced-toast';
        document.body.appendChild(container);
        return container;
    }

    function showToast(message, type = 'info', timeout = 5000) {
        if (!document.body) return;

        const container = ensureToastContainer();
        const item = document.createElement('div');
        item.className = `vikacg-enhanced-toast-item vikacg-enhanced-toast-${type}`;
        item.textContent = message;
        container.appendChild(item);

        setTimeout(() => {
            item.remove();
            if (!container.children.length) container.remove();
        }, timeout);
    }

    function gmGet(key, fallback) {
        if (typeof GM_getValue === 'function') {
            return GM_getValue(key, fallback);
        }

        try {
            const value = localStorage.getItem(key);
            return value ? JSON.parse(value) : fallback;
        } catch (e) {
            return fallback;
        }
    }

    function gmSet(key, value) {
        if (typeof GM_setValue === 'function') {
            GM_setValue(key, value);
            return;
        }

        try {
            localStorage.setItem(key, JSON.stringify(value));
        } catch (e) {
            debugLog('warn', `${LOG_PREFIX} 保存脚本状态失败:`, e);
        }
    }

    function gmDelete(key) {
        if (typeof GM_deleteValue === 'function') {
            GM_deleteValue(key);
            return;
        }

        try {
            localStorage.removeItem(key);
        } catch (e) {
            debugLog('warn', `${LOG_PREFIX} 删除脚本状态失败:`, e);
        }
    }

    function gmListKeys() {
        if (typeof GM_listValues === 'function') {
            return GM_listValues();
        }

        try {
            return Array.from({ length: localStorage.length }, (_, index) => localStorage.key(index)).filter(Boolean);
        } catch (e) {
            debugLog('warn', `${LOG_PREFIX} 读取脚本状态列表失败:`, e);
            return [];
        }
    }

    function clearPreviewCacheEntries() {
        let removed = 0;
        for (const key of gmListKeys()) {
            if (!String(key).startsWith(PREVIEW_CACHE_PREFIX)) continue;
            gmDelete(key);
            removed++;
        }
        return removed;
    }

    function clearPreviewCacheAndRefresh() {
        const removed = clearPreviewCacheEntries();
        resetPreviewDom();
        schedulePreviewProcessing(0);
        showToast(`已清理预览图片缓存：${removed} 条`, 'info');
        debugLog('log', `${LOG_PREFIX} 已清理预览图片缓存:`, removed);
        return removed;
    }

    function clampNumber(value, fallback, min, max) {
        const number = parseInt(value, 10);
        if (!Number.isFinite(number)) return fallback;
        return Math.min(max, Math.max(min, number));
    }

    function getPreviewCount() {
        return clampNumber(gmGet(PREVIEW_COUNT_KEY, PREVIEW_DEFAULT_COUNT), PREVIEW_DEFAULT_COUNT, 0, PREVIEW_MAX_COUNT);
    }

    function getPreviewMaxConcurrent() {
        return clampNumber(gmGet(PREVIEW_CONCURRENT_KEY, 6), 6, 1, 12);
    }

    function getRecommendKeywords() {
        const value = gmGet(RECOMMEND_KEYWORDS_KEY, DEFAULT_RECOMMEND_KEYWORDS);
        const list = Array.isArray(value) ? value : String(value || '').split(/[,，\s]+/);
        const keywords = list.map(item => String(item || '').trim()).filter(Boolean);
        return keywords.length > 0 ? keywords : DEFAULT_RECOMMEND_KEYWORDS;
    }

    // 签到时间段与 authorization 复用：站内 API、详情页、图床请求都统一补这个 header。
    function getTodayKey() {
        const date = new Date();
        const month = String(date.getMonth() + 1).padStart(2, '0');
        const day = String(date.getDate()).padStart(2, '0');
        return `${date.getFullYear()}-${month}-${day}`;
    }

    function getSignSlot() {
        return new Date().getHours() < 12 ? 'am' : 'pm';
    }

    function getCookieValue(name) {
        const escaped = name.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
        const match = document.cookie.match(new RegExp(`(?:^|;\\s*)${escaped}=([^;]*)`));
        return match ? decodeURIComponent(match[1]) : '';
    }

    function cleanTokenText(value) {
        if (!value || typeof value !== 'string') return '';

        return value.trim()
            .replace(/^Bearer\s+/i, '')
            .replace(/^["']|["']$/g, '');
    }

    function saveCapturedAuthorization(value, source) {
        const token = cleanTokenText(value);
        if (!token) return;

        gmSet(AUTH_HEADER_KEY, { token, source, capturedAt: Date.now() });
        debugLog('log', `${LOG_PREFIX} 已捕获 authorization:`, source, `length=${token.length}`);
    }

    function extractAuthorizationFromHeaders(headers) {
        if (!headers) return '';

        try {
            if (typeof Headers !== 'undefined' && headers instanceof Headers) {
                return headers.get('authorization') || headers.get('Authorization') || '';
            }
        } catch (e) {
            // Headers 可能来自页面上下文，instanceof 在沙盒里不可靠，继续用通用分支。
        }

        if (Array.isArray(headers)) {
            const item = headers.find(([key]) => String(key).toLowerCase() === 'authorization');
            return item ? item[1] : '';
        }

        if (typeof headers === 'object') {
            for (const [key, value] of Object.entries(headers)) {
                if (key.toLowerCase() === 'authorization') return value;
            }
        }

        return '';
    }

    function extractAuthorizationFromPayload(payload) {
        if (!payload || typeof payload !== 'string' || !/authorization/i.test(payload)) return '';

        try {
            const data = JSON.parse(payload);
            if (data && typeof data === 'object') {
                const value = data.authorization || data.Authorization;
                if (typeof value === 'string') return value;
            }
        } catch (e) {
            const match = payload.match(/["']authorization["']\s*:\s*["']([^"']+)["']/i);
            if (match) return match[1];
        }

        return '';
    }

    function installAuthorizationCapture() {
        const target = typeof unsafeWindow !== 'undefined' ? unsafeWindow : window;
        if (target.__vikacgEnhancedAuthCaptureInstalled) return;
        target.__vikacgEnhancedAuthCaptureInstalled = true;

        const originalFetch = target.fetch;
        if (typeof originalFetch === 'function') {
            target.fetch = function(input, init) {
                const headerAuth = extractAuthorizationFromHeaders(init && init.headers)
                    || extractAuthorizationFromHeaders(input && input.headers);
                if (headerAuth) saveCapturedAuthorization(headerAuth, 'fetch:header');

                const bodyAuth = extractAuthorizationFromPayload(init && init.body);
                if (bodyAuth) saveCapturedAuthorization(bodyAuth, 'fetch:body');

                return originalFetch.apply(this, arguments);
            };
        }

        const XHR = target.XMLHttpRequest;
        if (XHR && XHR.prototype) {
            const originalSetRequestHeader = XHR.prototype.setRequestHeader;
            const originalSend = XHR.prototype.send;

            XHR.prototype.setRequestHeader = function(name, value) {
                if (String(name).toLowerCase() === 'authorization') {
                    saveCapturedAuthorization(value, 'xhr:header');
                }
                return originalSetRequestHeader.apply(this, arguments);
            };

            XHR.prototype.send = function(body) {
                const bodyAuth = extractAuthorizationFromPayload(body);
                if (bodyAuth) saveCapturedAuthorization(bodyAuth, 'xhr:body');
                return originalSend.apply(this, arguments);
            };
        }
    }

    function parseStoredToken(value, acceptPlainToken = false) {
        const text = cleanTokenText(value);
        if (!text) return '';

        if (/^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+$/.test(text)) {
            return text;
        }

        if (acceptPlainToken && /^[^\s{}[\]"']{20,}$/.test(text)) {
            return text;
        }

        try {
            const data = JSON.parse(value);
            return findTokenInObject(data);
        } catch (e) {
            return '';
        }
    }

    function findTokenInObject(value) {
        if (!value) return '';
        if (typeof value === 'string') return parseStoredToken(value);
        if (Array.isArray(value)) {
            for (const item of value) {
                const token = findTokenInObject(item);
                if (token) return token;
            }
            return '';
        }
        if (typeof value !== 'object') return '';

        for (const [key, item] of Object.entries(value)) {
            if (/authorization|token/i.test(key)) {
                const token = findTokenInObject(item);
                if (token) return token;
            }
        }
        return '';
    }

    function getAuthTokenInfo() {
        const captured = gmGet(AUTH_HEADER_KEY, null);
        if (captured && captured.token) {
            if (captured.capturedAt && Date.now() - captured.capturedAt > AUTH_TTL_MS) {
                debugLog('warn', `${LOG_PREFIX} 已忽略过期 authorization 缓存:`, captured.source || '');
            } else {
                return { token: captured.token, source: captured.source || 'captured:authorization' };
            }
        }

        if (typeof captured === 'string') {
            const token = cleanTokenText(captured);
            if (token) return { token, source: 'captured:authorization' };
        }

        const authCookie = getCookieValue('authorization');
        if (authCookie) return { token: cleanTokenText(authCookie), source: 'cookie:authorization' };

        for (const storage of [localStorage, sessionStorage]) {
            const exactAuth = storage.getItem('authorization');
            if (exactAuth) {
                const token = cleanTokenText(exactAuth);
                if (token) return { token, source: `${storage === localStorage ? 'localStorage' : 'sessionStorage'}:authorization` };
            }

            for (let i = 0; i < storage.length; i++) {
                const key = storage.key(i);
                if (!key || !/authorization|token|auth|user/i.test(key)) continue;

                const acceptPlainToken = /authorization|(^|[._-])token$|access[_-]?token/i.test(key);
                const token = parseStoredToken(storage.getItem(key), acceptPlainToken);
                if (token) return { token, source: `${storage === localStorage ? 'localStorage' : 'sessionStorage'}:${key}` };
            }
        }

        return { token: '', source: '' };
    }

    function getAuthToken() {
        return getAuthTokenInfo().token;
    }

    function isVikacgRequestUrl(url) {
        try {
            const host = new URL(url, window.location.origin).hostname.toLowerCase();
            return /(?:^|\.)vikacg\.(?:com|cc|xyz|net|org)$/i.test(host);
        } catch (e) {
            return false;
        }
    }

    function withVikacgAuthorization(url, headers = {}, token = '') {
        const next = { ...headers };
        if (!isVikacgRequestUrl(url)) return next;

        const authToken = cleanTokenText(token || getAuthToken());
        if (!authToken) return next;

        const hasAuthorization = Object.keys(next).some(key => key.toLowerCase() === 'authorization');
        if (!hasAuthorization) {
            next.authorization = `Bearer ${authToken}`;
        }
        return next;
    }

    function getTokenId(token) {
        let hash = 0;
        for (let i = 0; i < token.length; i++) {
            hash = ((hash << 5) - hash + token.charCodeAt(i)) | 0;
        }
        return String(Math.abs(hash));
    }

    // 签到：按上午/下午记录尝试，成功和失败都会避免同一时间段反复请求。
    function getSignState(token) {
        const today = getTodayKey();
        const tokenId = getTokenId(token);
        const state = gmGet(SIGN_STATE_KEY, {});
        const userState = state[tokenId];
        if (userState && userState.date === today) {
            userState.slots = userState.slots || {};
            userState.attemptedSlots = userState.attemptedSlots || {};
            Object.keys(userState.slots).forEach(slot => {
                userState.attemptedSlots[slot] = true;
            });
            userState.doneCount = Object.keys(userState.slots).length;
            userState.attemptCount = Object.keys(userState.attemptedSlots).length;
            return { state, tokenId, userState };
        }

        return {
            state,
            tokenId,
            userState: { date: today, slots: {}, attemptedSlots: {}, doneCount: 0, attemptCount: 0, lastAttemptAt: 0, lockUntil: 0 },
        };
    }

    function saveSignState(state, tokenId, userState) {
        state[tokenId] = userState;
        gmSet(SIGN_STATE_KEY, state);
    }

    function acquireSignLock(token) {
        const now = Date.now();
        const slot = getSignSlot();
        const { state, tokenId, userState } = getSignState(token);

        if (userState.attemptCount >= SIGN_MAX_DAILY || userState.attemptedSlots[slot]) {
            return { skipped: true, reason: `今日已尝试${userState.attemptCount}/${SIGN_MAX_DAILY}个时段，本时段不再重复请求` };
        }

        if (userState.lockUntil && userState.lockUntil > now) {
            return { skipped: true, reason: '签到请求正在进行中，跳过重复触发' };
        }

        userState.attemptedSlots[slot] = true;
        userState.attemptCount = Object.keys(userState.attemptedSlots).length;
        userState.lockUntil = now + SIGN_LOCK_MS;
        userState.lastAttemptAt = now;
        saveSignState(state, tokenId, userState);
        return { state, tokenId, userState, slot };
    }

    function markSignDone(lock, message) {
        const { state, tokenId, userState, slot } = lock;
        userState.attemptedSlots = userState.attemptedSlots || {};
        userState.attemptedSlots[slot] = true;
        userState.attemptCount = Object.keys(userState.attemptedSlots).length;
        if (!userState.slots[slot]) {
            userState.slots[slot] = true;
            userState.doneCount = Object.keys(userState.slots).length;
        }
        userState.lockUntil = 0;
        userState.lastMessage = message;
        saveSignState(state, tokenId, userState);
    }

    function releaseSignLock(lock, message) {
        const { state, tokenId, userState } = lock;
        userState.lockUntil = 0;
        userState.lastMessage = message;
        saveSignState(state, tokenId, userState);
    }

    function requestSign(token) {
        return new Promise((resolve, reject) => {
            const apiBase = getApiBase();
            const url = `${apiBase}/api/vikacg/v1/userMission`;
            GM_xmlhttpRequest({
                method: 'POST',
                url,
                headers: withVikacgAuthorization(url, {
                    'content-type': 'application/json',
                    'user-agent': navigator.userAgent,
                    'referer': `${apiBase}/wallet/mission`,
                }, token),
                cookie: document.cookie,
                data: JSON.stringify({}),
                timeout: 15000,
                onload(response) {
                    debugLog('log', `${LOG_PREFIX} 签到响应:`, response.status, response.responseText);
                    let data;
                    try {
                        data = JSON.parse(response.responseText);
                    } catch (e) {
                        data = null;
                    }

                    if (response.status < 200 || response.status >= 300) {
                        reject(formatSignResult(data, `HTTP ${response.status}: ${(response.responseText || '').slice(0, 120)}`));
                        return;
                    }

                    if (data) {
                        resolve(data);
                    } else {
                        reject('解析签到响应失败');
                    }
                },
                onerror: reject,
                ontimeout() {
                    reject('签到请求超时');
                },
            });
        });
    }

    function getResponseMessage(data) {
        if (!data || typeof data !== 'object') return '';
        return data.message || data.msg || data.statusMessage || '';
    }

    function formatSignResult(data, fallback = '') {
        if (!data || typeof data !== 'object') return fallback || '签到响应为空';

        const parts = [];
        const responseMessage = getResponseMessage(data);
        if (responseMessage) parts.push(responseMessage);

        if (Object.prototype.hasOwnProperty.call(data, 'credit')) {
            parts.push(`获得积分：${data.credit}`);
        }

        if (data.mission && Object.prototype.hasOwnProperty.call(data.mission, 'my_credit')) {
            parts.push(`当前积分：${data.mission.my_credit}`);
        }

        return parts.length > 0 ? parts.join('，') : JSON.stringify(data);
    }

    async function runDailySign() {
        if (isSigning) return;

        const tokenInfo = getAuthTokenInfo();
        const token = tokenInfo.token;
        if (!token) {
            const message = '签到跳过：未找到 authorization，请确认已登录且脚本运行的是维咔ACG增强 2.0';
            debugLog('log', `${LOG_PREFIX} ${message}`);
            showToast(message, 'warning', 8000);
            return;
        }

        const lock = acquireSignLock(token);
        if (lock && lock.skipped) {
            debugLog('log', `${LOG_PREFIX} 签到跳过：${lock.reason}`);
            return;
        }

        isSigning = true;
        try {
            debugLog('log', `${LOG_PREFIX} 开始签到，token来源: ${tokenInfo.source}, API: ${getApiBase()}`);
            const data = await requestSign(token);
            const message = formatSignResult(data);
            markSignDone(lock, message);
            debugLog('log', `${LOG_PREFIX} ${message}`);
            showToast(message, Object.prototype.hasOwnProperty.call(data || {}, 'credit') ? 'success' : 'info');
        } catch (e) {
            const message = `签到失败：${String(e)}`;
            releaseSignLock(lock, message);
            debugLog('warn', `${LOG_PREFIX} 签到失败:`, e);
            showToast(message, 'error');
        } finally {
            isSigning = false;
        }
    }

    async function fetchPostContent(postId) {
        return new Promise((resolve, reject) => {
            const url = `${getApiBase()}/api/vikacg/v1/getPost`;
            GM_xmlhttpRequest({
                method: 'POST',
                url,
                headers: withVikacgAuthorization(url, { 'Content-Type': 'application/json' }),
                data: JSON.stringify({ id: parseInt(postId) }),
                onload: function(response) {
                    try {
                        const data = JSON.parse(response.responseText);
                        if (data.status === 'success' && data.data) {
                            const contents = collectPostContents(data.data);
                            if (contents.length > 0) {
                                resolve(contents.join('\n'));
                            } else {
                                reject('API响应中没有可用内容');
                            }
                        } else {
                            reject('API返回失败');
                        }
                    } catch (e) {
                        reject('解析API响应失败');
                    }
                },
                onerror: reject
            });
        });
    }

    async function fetchPostDetailHtml(postId) {
        return new Promise((resolve, reject) => {
            const url = `${getApiBase()}/p/${postId}`;
            GM_xmlhttpRequest({
                method: 'GET',
                url,
                headers: withVikacgAuthorization(url, {
                    accept: 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
                    referer: window.location.href,
                }),
                timeout: 20000,
                onload(response) {
                    if (response.status >= 200 && response.status < 300 && response.responseText) {
                        resolve(response.responseText);
                    } else {
                        reject(`详情页加载失败：HTTP ${response.status}`);
                    }
                },
                onerror: reject,
                ontimeout() {
                    reject('详情页请求超时');
                },
            });
        });
    }

    // 内容提取：API 和详情页 HTML 都会被用于预览图与 external 直链匹配。
    function collectPostContents(post) {
        const contents = [];
        const seen = new Set();

        function add(value) {
            if (!value) return;

            if (typeof value === 'string') {
                const text = value.trim();
                if (text && !seen.has(text)) {
                    seen.add(text);
                    contents.push(text);
                }
                return;
            }

            if (Array.isArray(value)) {
                value.forEach(add);
                return;
            }

            if (typeof value === 'object') {
                add(value.content);
                add(value.html);
                add(value.text);
                add(value.value);
            }
        }

        add(post.content);
        add(post.hidden_content);
        return contents;
    }

    function decodeHtmlText(text) {
        const textarea = document.createElement('textarea');
        textarea.innerHTML = text || '';
        return textarea.value;
    }

    function cleanHtmlText(html) {
        return decodeHtmlText(html)
            .replace(/<[^>]*>/g, '')
            .replace(/\s+/g, ' ')
            .trim();
    }

    function normalizeUrl(url) {
        return decodeHtmlText(url)
            .trim()
            .replace(/[.,!?，。！？、；;：:）)\]】>]+$/g, '')
            .replace(/#$/, '');
    }

    function normalizeExternalHref(href) {
        if (!href) return '';

        const raw = href.trim();
        const match = raw.match(/\/external\?e=[^&#"']+/i);
        if (match) return match[0];

        try {
            const url = new URL(raw, window.location.origin);
            if (url.pathname === '/external' && url.searchParams.has('e')) {
                return `/external?e=${url.searchParams.get('e')}`;
            }
        } catch (e) {
            // 忽略非URL字符串，交给原链接兜底。
        }

        return raw;
    }

    function getHost(url) {
        try {
            return new URL(url).hostname.toLowerCase();
        } catch (e) {
            return '';
        }
    }

    function isImageUrl(url) {
        try {
            return /\.(?:jpe?g|png|gif|webp|bmp|svg|avif|ico)$/i.test(new URL(url).pathname);
        } catch (e) {
            return /\.(?:jpe?g|png|gif|webp|bmp|svg|avif|ico)(?:[?#].*)?$/i.test(url);
        }
    }

    function shouldKeepUrl(url) {
        const host = getHost(url);
        if (!host) return false;
        if (/(\.|^)vikacg\.(com|cc|xyz|net|org)$/i.test(host)) return false;
        if (host === 'image.acg.lol' || isVikacgImageHost(host) || host === 'picjs.xyz' || host.endsWith('.picjs.xyz')) return false;
        if (url.includes('/external?e=') || url.includes('photo://')) return false;
        return !isImageUrl(url);
    }

    function shouldKeepMappingUrl(url) {
        const host = getHost(url);
        if (!host) return false;
        if (/(\.|^)vikacg\.(com|cc|xyz|net|org)$/i.test(host)) return false;
        if (isVikacgImageHost(host) || host === 'picjs.xyz' || host.endsWith('.picjs.xyz')) return false;
        if (url.includes('/external?e=') || url.includes('photo://')) return false;
        return true;
    }

    function extractJsonUrls(html) {
        const cleanHtml = html
            .replace(/<img[^>]*>/gi, '')
            .replace(/<source[^>]*>/gi, '');
        
        const urls = [];
        const seen = new Set();
        const urlRegex = /https?:\/\/[^\s"'<>]+/gi;
        let match;
        while ((match = urlRegex.exec(cleanHtml)) !== null) {
            const rawUrl = match[0];
            const url = normalizeUrl(rawUrl);
            if (!shouldKeepMappingUrl(url) || seen.has(url)) {
                continue;
            }

            seen.add(url);
            const beforeHtml = cleanHtml.substring(Math.max(0, match.index - 150), match.index);
            const afterEnd = match.index + rawUrl.length;
            const afterHtml = cleanHtml.substring(afterEnd, Math.min(cleanHtml.length, afterEnd + 150));
            const before = cleanHtmlText(beforeHtml).slice(-20);
            const after = cleanHtmlText(afterHtml).slice(0, 20);
            urls.push({ url, before, after, index: match.index });
        }
        debugLog('log', `${LOG_PREFIX} JSON中找到URL数量:`, urls.length);
        return urls;
    }

    function createHtmlRoot(html) {
        const template = document.createElement('template');
        template.innerHTML = html || '';
        return template.content;
    }

    // 列表增强样式：预览图横排放在摘要下方，推荐广告卡片直接隐藏。
    function injectPreviewStyles() {
        if (document.getElementById('vikacg-enhanced-preview-style')) return;

        const style = document.createElement('style');
        style.id = 'vikacg-enhanced-preview-style';
        style.textContent = `
            .vikacg-enhanced-preview {
                display: flex;
                gap: 8px;
                margin-top: 8px;
                width: 100%;
                flex: 0 0 100%;
                align-self: stretch;
                max-width: 100%;
                overflow-x: auto;
                overflow-y: hidden;
                padding-bottom: 2px;
                scrollbar-width: thin;
            }
            .vikacg-enhanced-preview-thumb {
                flex: 0 0 128px;
                height: 88px;
                border-radius: 6px;
                overflow: hidden;
                background: rgba(148, 163, 184, .16);
                cursor: zoom-in;
                display: flex;
                align-items: center;
                justify-content: center;
            }
            .vikacg-enhanced-preview-thumb img {
                width: 100%;
                height: 100%;
                object-fit: cover;
                display: block;
                opacity: 0;
                transition: opacity .2s ease;
            }
            .vikacg-enhanced-preview-thumb img.is-loaded {
                opacity: 1;
            }
            .vikacg-enhanced-preview-state {
                color: #8a8f98;
                font-size: 12px;
                line-height: 1.5;
                padding: 4px 0;
            }
            .${RECOMMEND_HIDDEN_CLASS} {
                display: none !important;
            }
            @media (min-width: 768px) {
                .vikacg-enhanced-preview-thumb {
                    flex-basis: 154px;
                    height: 108px;
                }
            }
            @media (max-width: 640px) {
                .vikacg-enhanced-preview-thumb {
                    flex-basis: 96px;
                    height: 72px;
                }
            }
        `;
        document.head.appendChild(style);
    }

    // 预览缓存：缓存过滤后的非封面图片，减少列表反复滚动时的详情页请求。
    function getPreviewCache(postId) {
        const cached = gmGet(`${PREVIEW_CACHE_PREFIX}${postId}`, null);
        if (!cached || !Array.isArray(cached.images)) return null;
        if (Date.now() - (cached.time || 0) > PREVIEW_CACHE_TTL_MS) return null;
        return cached;
    }

    function setPreviewCache(postId, images) {
        gmSet(`${PREVIEW_CACHE_PREFIX}${postId}`, { images, time: Date.now() });
    }

    function extractPostIdFromHref(href) {
        try {
            const url = new URL(href, window.location.origin);
            const match = url.pathname.match(/\/p\/(\d+)/);
            return match ? match[1] : '';
        } catch (e) {
            const match = String(href || '').match(/\/p\/(\d+)/);
        return match ? match[1] : '';
        }
    }

    function isRecommendationBadge(el) {
        if (!el || el.tagName !== 'SPAN') return false;

        const text = cleanHtmlText(el.textContent || '').replace(/\s+/g, '');
        return getRecommendKeywords().some(keyword => text === keyword.replace(/\s+/g, ''));
    }

    function findRecommendationBadge(host) {
        if (!host) return null;
        return Array.from(host.querySelectorAll('span')).find(isRecommendationBadge) || null;
    }

    function findRecommendationCardHost(badge) {
        const link = badge.closest('a[href]');
        if (link) {
            return extractPostIdFromHref(link.getAttribute('href') || link.href)
                ? findPostCardHost(link)
                : link;
        }

        for (let el = badge.parentElement; el && el !== document.body; el = el.parentElement) {
            const nestedLink = el.matches('a[href]') ? el : el.querySelector('a[href]');
            if (!nestedLink) continue;

            return extractPostIdFromHref(nestedLink.getAttribute('href') || nestedLink.href)
                ? findPostCardHost(nestedLink)
                : nestedLink;
        }

        return null;
    }

    function hideRecommendedPostCard(host) {
        if (!host || host.classList.contains(RECOMMEND_HIDDEN_CLASS)) return false;

        revokePreviewObjectUrls(host);
        host.querySelectorAll('.vikacg-enhanced-preview').forEach(el => el.remove());
        delete host.dataset.vikacgEnhancedPreviewId;
        host.classList.add(RECOMMEND_HIDDEN_CLASS);
        host.style.setProperty('display', 'none', 'important');
        debugLog('log', `${LOG_PREFIX} 已屏蔽推荐帖子`);
        return true;
    }

    function hideRecommendedPostCards() {
        const seenHosts = new Set();
        let hidden = 0;

        for (const badge of Array.from(document.querySelectorAll('span')).filter(isRecommendationBadge)) {
            const host = findRecommendationCardHost(badge);
            if (!host || seenHosts.has(host)) continue;

            seenHosts.add(host);
            if (hideRecommendedPostCard(host)) hidden++;
        }

        return hidden;
    }

    // 列表扫描：同时承担推荐广告屏蔽和多图预览挂载，MutationObserver 会重复调度它。
    function getPostListLinks() {
        const links = [];
        for (const link of Array.from(document.querySelectorAll('a[href]'))) {
            const postId = extractPostIdFromHref(link.getAttribute('href') || link.href);
            if (!postId) continue;
            if (link.closest('.prose, .vikacg-enhanced-preview')) continue;
            if (link.closest(`.${RECOMMEND_HIDDEN_CLASS}`)) continue;

            links.push({ link, postId });
        }
        return links;
    }

    function findPreviewInsertTarget(host) {
        const textBlocks = Array.from(host.querySelectorAll('p, [class*="line-clamp"], [class*="desc"], [class*="summary"]'));
        const summary = textBlocks.find(el => {
            if (/^H[1-6]$/i.test(el.tagName)) return false;
            const text = el.textContent.trim();
            const className = String(el.className || '');
            return text.length > 8 && /line-clamp|overflow-hidden|text-gray|text-xs|text-sm|desc|summary/i.test(className);
        });
        if (summary) return summary;

        return textBlocks.find(el => !/^H[1-6]$/i.test(el.tagName) && el.textContent.trim().length > 12) || null;
    }

    function findPreviewInsertAnchor(host) {
        const summary = findPreviewInsertTarget(host);
        if (!summary) return null;

        for (let el = summary; el && el !== host; el = el.parentElement) {
            const parent = el.parentElement;
            if (!parent || parent === host) continue;

            const className = String(parent.className || '');
            if (/flex/i.test(className) && /justify-between|items-start|gap-/i.test(className) && parent.querySelector('img')) {
                return parent;
            }
        }

        return summary;
    }

    function findCardCoverSrc(host) {
        const images = Array.from(host.querySelectorAll('img[src], img[data-src]'));
        for (const img of images) {
            const raw = img.getAttribute('data-src') || img.getAttribute('src');
            const src = normalizePreviewImageSrc(raw);
            if (shouldKeepPreviewImage(src)) return src;
        }
        return '';
    }

    function findPostCardHost(link) {
        const wrappingLink = link.closest('a[href*="/p/"]') || link;
        if (findPreviewInsertTarget(wrappingLink)) return wrappingLink;

        for (let el = link.parentElement; el && el !== document.body; el = el.parentElement) {
            const hasPostLink = el.matches('a[href*="/p/"]') || el.querySelector('a[href*="/p/"]');
            if (!hasPostLink) continue;

            const className = String(el.className || '');
            if (findPreviewInsertTarget(el) || /shadow-card|result|post|item|rounded/i.test(className)) {
                return el;
            }
        }

        return wrappingLink;
    }

    function isElementNearViewport(el, margin = 360) {
        const rect = el.getBoundingClientRect();
        const height = window.innerHeight || document.documentElement.clientHeight || 0;
        return rect.bottom >= -margin && rect.top <= height + margin;
    }

    function resetPreviewDom() {
        document.querySelectorAll('.vikacg-enhanced-preview').forEach(el => {
            revokePreviewObjectUrls(el);
            el.remove();
        });
        document.querySelectorAll('[data-vikacg-enhanced-preview-id]').forEach(el => {
            delete el.dataset.vikacgEnhancedPreviewId;
        });
    }

    function ensurePreviewObservers() {
        if (!previewFetchObserver && typeof IntersectionObserver !== 'undefined') {
            previewFetchObserver = new IntersectionObserver(entries => {
                entries.forEach(entry => {
                    if (!entry.isIntersecting) return;
                    const container = entry.target;
                    previewFetchObserver.unobserve(container);
                    loadPreviewForContainer(container);
                });
            }, { rootMargin: '360px 0px' });
        }

    }

    function schedulePreviewProcessing(delay = 300) {
        clearTimeout(previewRetryTimer);
        previewRetryTimer = setTimeout(() => {
            previewRetryTimer = null;
            processPreviewCards();
        }, delay);
    }

    function processPreviewCards() {
        if (!document.body) return;

        injectPreviewStyles();
        const hiddenRecommendations = hideRecommendedPostCards();
        const count = getPreviewCount();
        if (count <= 0) {
            debugLog('log', `${LOG_PREFIX} 预览已关闭，跳过扫描`);
            resetPreviewDom();
            return;
        }

        ensurePreviewObservers();

        const seenHosts = new Set();
        const links = getPostListLinks();
        const summary = {
            candidateLinks: links.length,
            cardHosts: 0,
            duplicateLinks: 0,
            created: 0,
            reused: 0,
            noHost: 0,
            noAnchor: 0,
            hiddenRecommendations,
        };
        for (const { link, postId } of links) {
            const host = findPostCardHost(link);
            if (!host) {
                summary.noHost++;
                continue;
            }
            if (findRecommendationBadge(host)) {
                if (hideRecommendedPostCard(host)) summary.hiddenRecommendations++;
                continue;
            }
            if (seenHosts.has(host)) {
                summary.duplicateLinks++;
                continue;
            }
            seenHosts.add(host);
            summary.cardHosts++;

            const insertAnchor = findPreviewInsertAnchor(host);
            if (!insertAnchor) {
                summary.noAnchor++;
                continue;
            }

            const oldPreview = host.querySelector(`.vikacg-enhanced-preview[data-post-id="${postId}"]`);
            if (oldPreview) {
                if (oldPreview.previousElementSibling !== insertAnchor) {
                    insertAnchor.after(oldPreview);
                }
                summary.reused++;
                continue;
            }

            host.dataset.vikacgEnhancedPreviewId = postId;
            const preview = document.createElement('div');
            preview.className = 'vikacg-enhanced-preview';
            preview.dataset.postId = postId;
            preview.dataset.coverSrc = findCardCoverSrc(host);
            preview.innerHTML = '<span class="vikacg-enhanced-preview-state">预览排队中...</span>';
            insertAnchor.after(preview);

            if (previewFetchObserver) {
                previewFetchObserver.observe(preview);
            }
            loadPreviewForContainer(preview);
            summary.created++;
        }
        logPreviewScanSummary(summary);
    }

    function logPreviewScanSummary(summary) {
        summary.totalPreviewCards = document.querySelectorAll('.vikacg-enhanced-preview').length;
        summary.pending = previewPending;
        summary.queued = previewQueue.length;

        const signature = [
            getRouteKey(),
            summary.candidateLinks,
            summary.cardHosts,
            summary.created,
            summary.reused,
            summary.noHost,
            summary.noAnchor,
            summary.hiddenRecommendations,
            summary.totalPreviewCards,
        ].join('|');
        if (signature === previewScanLogState.signature) return;

        previewScanLogState = { signature, time: Date.now() };
        debugLog('log', `${LOG_PREFIX} 预览扫描汇总:`, summary);
    }

    async function loadPreviewForContainer(container) {
        if (!container.isConnected || container.dataset.loading || container.dataset.loaded) return;

        const postId = container.dataset.postId;
        const count = getPreviewCount();
        if (!postId || count <= 0) {
            container.remove();
            return;
        }

        container.dataset.loading = '1';
        container.innerHTML = '<span class="vikacg-enhanced-preview-state">预览加载中...</span>';
        try {
            logPreviewImage('info', '开始加载帖子', {
                postId,
                cover: Boolean(container.dataset.coverSrc),
            });

            const coverSrc = container.dataset.coverSrc || '';
            const cached = getPreviewCache(postId);
            const previewImages = cached ? cached.images : await fetchPreviewImagesWithSlot(postId, coverSrc);
            if (!cached) setPreviewCache(postId, previewImages);

            logPreviewImage('info', '图片就绪', {
                postId,
                renderImages: previewImages.length,
            });
            renderPreviewImages(container, previewImages.slice(0, count));
            container.dataset.loaded = '1';
        } catch (e) {
            debugLog('warn', `${LOG_PREFIX} 预览加载失败:`, postId, e);
            logPreviewImage('warn', '接口失败，跳过封面兜底', {
                postId,
                error: String(e),
            });
            container.dataset.failureReason = '预览加载失败';
            renderPreviewImages(container, []);
            container.dataset.loaded = '1';
        } finally {
            delete container.dataset.loading;
        }
    }

    async function fetchPreviewImagesWithSlot(postId, coverSrc) {
        await acquirePreviewSlot();
        try {
            const apiContent = await fetchPostContent(postId);
            const apiImages = extractPreviewImages(apiContent, PREVIEW_MAX_COUNT * 2);
            let images = filterNonCoverPreviewImages(apiImages, coverSrc);
            logPreviewImage('info', 'API图片提取完成', {
                postId,
                apiImages: apiImages.length,
                nonCoverImages: images.length,
            });

            if (images.length >= getPreviewCount()) {
                return images;
            }

            const pageHtml = await fetchPostDetailHtml(postId);
            const pageImages = extractPreviewImages(pageHtml, PREVIEW_MAX_COUNT * 3);
            images = filterNonCoverPreviewImages([...apiImages, ...pageImages], coverSrc);
            logPreviewImage('info', '详情页图片提取完成', {
                postId,
                pageImages: pageImages.length,
                nonCoverImages: images.length,
            });
            return images;
        } finally {
            releasePreviewSlot();
        }
    }

    function acquirePreviewSlot() {
        if (previewPending < getPreviewMaxConcurrent()) {
            previewPending++;
            return Promise.resolve();
        }

        return new Promise(resolve => {
            previewQueue.push(() => {
                previewPending++;
                resolve();
            });
        });
    }

    function releasePreviewSlot() {
        previewPending = Math.max(0, previewPending - 1);
        const next = previewQueue.shift();
        if (next) setTimeout(next, 120);
    }

    function parseSrcset(srcset) {
        if (!srcset) return '';
        const first = srcset.split(',')[0] || '';
        return first.trim().split(/\s+/)[0] || '';
    }

    function getCurrentVikacgSuffix() {
        const match = window.location.hostname.match(/(?:^|\.)vikacg\.(com|cc|xyz|net|org)$/i);
        return match ? match[1].toLowerCase() : '';
    }

    function isVikacgImageHost(host) {
        return /^image\.vikacg\.(com|cc|xyz|net|org)$/i.test(host || '');
    }

    function normalizePreviewImageSrc(src) {
        const text = decodeHtmlText(src || '').trim();
        if (!text || /^(?:data|blob|photo):/i.test(text)) return '';

        try {
            return new URL(text, window.location.origin).href;
        } catch (e) {
            return '';
        }
    }

    function getComparableImageKey(src) {
        try {
            const url = new URL(src, window.location.origin);
            return `${url.hostname.toLowerCase()}${url.pathname}`.toLowerCase();
        } catch (e) {
            return String(src || '').split(/[?#]/)[0].toLowerCase();
        }
    }

    function isSamePreviewImage(a, b) {
        if (!a || !b) return false;
        return getComparableImageKey(a) === getComparableImageKey(b);
    }

    function filterNonCoverPreviewImages(images, coverSrc) {
        const result = [];
        const seen = new Set();
        for (const src of images) {
            if (!src || isSamePreviewImage(src, coverSrc)) continue;

            const key = getComparableImageKey(src);
            if (seen.has(key)) continue;

            seen.add(key);
            result.push(src);
        }
        return result;
    }

    function getPreviewImageFallbacks(src) {
        const fallbacks = [];
        try {
            const url = new URL(src);
            if (!isVikacgImageHost(url.hostname)) return fallbacks;

            const currentSuffix = getCurrentVikacgSuffix();
            for (const suffix of [currentSuffix, 'cc', 'xyz', 'com', 'net', 'org']) {
                if (!suffix) continue;
                const next = new URL(url.href);
                next.hostname = `image.vikacg.${suffix}`;
                if (next.href !== url.href && !fallbacks.includes(next.href)) {
                    fallbacks.push(next.href);
                }
            }
        } catch (e) {
            // 非标准 URL 不做兜底。
        }
        return fallbacks;
    }

    function getPreviewLogUrl(src) {
        try {
            const url = new URL(src, window.location.origin);
            return `${url.origin}${url.pathname}${url.search}`;
        } catch (e) {
            return String(src || '');
        }
    }

    function logPreviewImage(level, message, data = {}) {
        debugLog(level, `${LOG_PREFIX} 预览图片${message}`, data);
    }

    function shouldKeepPreviewImage(url) {
        if (!url || !isImageUrl(url)) return false;
        const host = getHost(url);
        const lower = url.toLowerCase();
        if (/avatar|weblogo|favicon|apple-touch|maskable|default\.|site_head|emoji|smiley|iconfont|\/icon|\/assets\/moonlight\//i.test(lower)) {
            return false;
        }
        if (isVikacgImageHost(host)) return true;
        if (/(^|\.)vikacg\.(com|cc|xyz|net|org)$/i.test(host)) return false;
        return true;
    }

    function revokePreviewObjectUrl(img) {
        const objectUrl = img.dataset.objectUrl;
        if (objectUrl) {
            URL.revokeObjectURL(objectUrl);
            delete img.dataset.objectUrl;
        }
    }

    function revokePreviewObjectUrls(root) {
        root.querySelectorAll('img[data-object-url]').forEach(revokePreviewObjectUrl);
    }

    function setPreviewImageSrc(img, src) {
        if (!src) return;

        img.dataset.rawSrc = src;
        img.dataset.pendingSrc = src;
        img.classList.remove('is-loaded');
        revokePreviewObjectUrl(img);

        if (!isVikacgRequestUrl(src)) {
            img.src = src;
            return;
        }

        loadAuthorizedPreviewImage(img, src);
    }

    function loadAuthorizedPreviewImage(img, src) {
        const tokenInfo = getAuthTokenInfo();
        const token = tokenInfo.token;
        if (!token) {
            const retry = parseInt(img.dataset.authRetry || '0', 10);
            if (retry < PREVIEW_AUTH_RETRY_MAX) {
                img.dataset.authRetry = String(retry + 1);
                logPreviewImage('warn', '等待 authorization', {
                    url: getPreviewLogUrl(src),
                    retry: retry + 1,
                    max: PREVIEW_AUTH_RETRY_MAX,
                });
                setTimeout(() => {
                    if (img.isConnected && img.dataset.pendingSrc === src && !img.src) {
                        loadAuthorizedPreviewImage(img, src);
                    }
                }, PREVIEW_AUTH_RETRY_DELAY_MS);
                return;
            }

            logPreviewImage('error', '缺少 authorization，停止站内图片加载', {
                url: getPreviewLogUrl(src),
            });
            return;
        }

        delete img.dataset.authRetry;
        logPreviewImage('info', '开始授权请求', {
            url: getPreviewLogUrl(src),
            tokenSource: tokenInfo.source || '',
            tokenLength: token.length,
        });

        GM_xmlhttpRequest({
            method: 'GET',
            url: src,
            headers: withVikacgAuthorization(src, {
                accept: 'image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8',
                referer: window.location.href,
            }, token),
            responseType: 'blob',
            timeout: 20000,
            onload(response) {
                if (img.dataset.pendingSrc !== src) return;

                const contentType = response.responseHeaders?.match(/content-type:\s*([^\r\n]+)/i)?.[1] || '';
                const size = response.response instanceof Blob
                    ? response.response.size
                    : response.response
                        ? String(response.response).length
                        : 0;
                logPreviewImage(response.status >= 200 && response.status < 300 ? 'info' : 'warn', '授权响应', {
                    url: getPreviewLogUrl(src),
                    status: response.status,
                    contentType,
                    size,
                });

                if (response.status < 200 || response.status >= 300 || !response.response) {
                    img.dispatchEvent(new Event('error'));
                    return;
                }

                const blob = response.response instanceof Blob
                    ? response.response
                    : new Blob([response.response], { type: contentType || 'image/*' });
                const objectUrl = URL.createObjectURL(blob);
                img.dataset.objectUrl = objectUrl;
                img.src = objectUrl;
            },
            onerror(error) {
                if (img.dataset.pendingSrc === src) {
                    logPreviewImage('error', '授权请求失败', {
                        url: getPreviewLogUrl(src),
                        error,
                    });
                    img.dispatchEvent(new Event('error'));
                }
            },
            ontimeout() {
                if (img.dataset.pendingSrc === src) {
                    logPreviewImage('error', '授权请求超时', {
                        url: getPreviewLogUrl(src),
                    });
                    img.dispatchEvent(new Event('error'));
                }
            },
        });
    }

    function extractPreviewImages(html, limit) {
        const root = createHtmlRoot(html);
        const images = [];
        const seen = new Set();
        const nodes = Array.from(root.querySelectorAll('img, source[srcset]'));

        for (const node of nodes) {
            const raw = node.getAttribute('zoomfile')
                || node.getAttribute('file')
                || node.getAttribute('data-actualsrc')
                || node.getAttribute('actualsrc')
                || node.getAttribute('data-original')
                || node.getAttribute('data-src')
                || node.getAttribute('src')
                || parseSrcset(node.getAttribute('srcset'));
            const src = normalizePreviewImageSrc(raw);
            if (!shouldKeepPreviewImage(src) || seen.has(src)) continue;

            seen.add(src);
            images.push(src);
            if (images.length >= limit) break;
        }

        const vikacgImages = images.filter(url => isVikacgRequestUrl(url));
        if (vikacgImages.length > 0) {
            logPreviewImage('info', '提取到站内图片', {
                count: vikacgImages.length,
                sample: vikacgImages.slice(0, 3).map(getPreviewLogUrl),
            });
        }

        return images;
    }

    function renderPreviewImages(container, images) {
        if (!images.length) {
            revokePreviewObjectUrls(container);
            container.dataset.loaded = '1';
            container.dataset.empty = '1';
            if (getLogConsoleLevel() === 'debug') {
                container.style.display = '';
                const reason = container.dataset.failureReason || '未找到非封面预览图';
                container.replaceChildren();
                const state = document.createElement('span');
                state.className = 'vikacg-enhanced-preview-state';
                state.textContent = reason;
                container.appendChild(state);
            } else {
                container.style.display = 'none';
                container.replaceChildren();
            }
            return;
        }

        container.style.display = '';
        delete container.dataset.empty;
        delete container.dataset.failureReason;
        revokePreviewObjectUrls(container);
        container.replaceChildren();
        const fragment = document.createDocumentFragment();
        images.forEach(src => {
            const thumb = document.createElement('div');
            thumb.className = 'vikacg-enhanced-preview-thumb';
            thumb.title = '打开预览图';

            const img = document.createElement('img');
            img.alt = '';
            img.loading = 'eager';
            img.referrerPolicy = 'origin';
            img.dataset.src = src;
            img.dataset.fallbacks = JSON.stringify(getPreviewImageFallbacks(src));
            img.onload = () => {
                img.classList.add('is-loaded');
                if (isVikacgRequestUrl(img.dataset.rawSrc || src)) {
                    logPreviewImage('info', '渲染成功', {
                        url: getPreviewLogUrl(img.dataset.rawSrc || src),
                        renderedSrc: img.src.startsWith('blob:') ? 'blob:' : getPreviewLogUrl(img.src),
                    });
                }
            };
            img.onerror = () => {
                let fallbacks = [];
                try {
                    fallbacks = JSON.parse(img.dataset.fallbacks || '[]');
                } catch (e) {
                    fallbacks = [];
                }

                const next = fallbacks.shift();
                if (next) {
                    logPreviewImage('warn', '加载失败，尝试备用域名', {
                        failedUrl: getPreviewLogUrl(img.dataset.rawSrc || src),
                        nextUrl: getPreviewLogUrl(next),
                        remaining: fallbacks.length,
                    });
                    img.dataset.fallbacks = JSON.stringify(fallbacks);
                    setPreviewImageSrc(img, next);
                    return;
                }

                logPreviewImage('error', '所有备用地址均失败，移除缩略图', {
                    url: getPreviewLogUrl(img.dataset.rawSrc || src),
                    currentSrc: img.src.startsWith('blob:') ? 'blob:' : getPreviewLogUrl(img.src),
                });
                revokePreviewObjectUrl(img);
                thumb.remove();
                if (!container.querySelector('.vikacg-enhanced-preview-thumb')) {
                    container.dataset.empty = '1';
                    container.style.display = 'none';
                }
            };

            thumb.addEventListener('click', e => {
                e.preventDefault();
                e.stopPropagation();
                window.open(img.dataset.rawSrc || src, '_blank', 'noopener');
            });

            thumb.appendChild(img);
            fragment.appendChild(thumb);
            setPreviewImageSrc(img, src);
        });
        container.appendChild(fragment);
    }

    function extractDomain(text) {
        const match = text.match(/网页链接\(([^)]+)\)/) || text.match(/\(([^)]+\.[^)]+)\)/);
        return match ? match[1].trim().toLowerCase() : null;
    }

    // 直链映射：不访问 external 跳转页，直接用页面/API 内容还原真实链接。
    function extractExternalLinks(html) {
        const links = [];
        const seen = new Set();
        const root = createHtmlRoot(html);
        const anchors = Array.from(root.querySelectorAll('a[href*="external?e="]'));

        for (const anchor of anchors) {
            const href = normalizeExternalHref(anchor.getAttribute('href') || anchor.href);
            if (!href || seen.has(href)) continue;

            seen.add(href);
            const text = cleanHtmlText(anchor.innerHTML || anchor.textContent || '');
            links.push({ href, domain: extractDomain(text), text });
        }

        debugLog('log', `${LOG_PREFIX} HTML中找到external数量:`, links.length);
        return links;
    }

    function addMapping(href, url, reason) {
        const key = normalizeExternalHref(href);
        if (!key || !url) return false;

        if (urlMap[key] && urlMap[key] !== url) {
            debugLog('warn', `${LOG_PREFIX} 映射冲突，保留已有值:`, key, urlMap[key], '忽略:', url);
            return false;
        }

        if (!urlMap[key]) {
            urlMap[key] = url;
            debugLog('log', `${LOG_PREFIX} ${reason}:`, key, '->', url);
            return true;
        }

        return false;
    }

    function isDomainMatch(url, domain) {
        if (!domain) return false;

        const host = getHost(url);
        return host === domain || host.endsWith(`.${domain}`) || url.includes(domain);
    }

    function getUnmappedExternalLinks(externalLinks) {
        return externalLinks.filter(ext => !urlMap[normalizeExternalHref(ext.href)]);
    }

    function getUnusedJsonUrls(jsonUrls, usedUrls) {
        const result = [];
        const seen = new Set();
        for (const item of jsonUrls) {
            if (usedUrls.has(item.url) || seen.has(item.url)) continue;
            seen.add(item.url);
            result.push(item);
        }
        return result;
    }

    function getJsonContextText(item) {
        return cleanHtmlText(`${item.before || ''} ${item.after || ''}`).toLowerCase();
    }

    function addUniqueDomainMappings(externalLinks, jsonUrls, usedUrls) {
        let added = 0;
        for (const ext of externalLinks) {
            if (!ext.domain || urlMap[ext.href]) continue;

            const matches = getUnusedJsonUrls(jsonUrls, usedUrls)
                .filter(item => isDomainMatch(item.url, ext.domain));

            if (matches.length === 1 && addMapping(ext.href, matches[0].url, '域名匹配')) {
                usedUrls.add(matches[0].url);
                added++;
            }
        }
        return added;
    }

    function addContextMappings(externalLinks, jsonUrls, usedUrls) {
        let added = 0;
        for (const ext of externalLinks) {
            if (urlMap[ext.href]) continue;

            const extText = cleanHtmlText(ext.text || '').toLowerCase();
            if (!extText || extText.length < 4) continue;

            const matches = getUnusedJsonUrls(jsonUrls, usedUrls).filter(item => {
                const context = getJsonContextText(item);
                return context && (context.includes(extText) || extText.includes(context));
            });

            if (matches.length === 1 && addMapping(ext.href, matches[0].url, '文本上下文匹配')) {
                usedUrls.add(matches[0].url);
                added++;
            }
        }
        return added;
    }

    function addRemainingOrderMappings(externalLinks, jsonUrls, usedUrls) {
        const remainingLinks = getUnmappedExternalLinks(externalLinks);
        const remainingUrls = getUnusedJsonUrls(jsonUrls, usedUrls);
        if (remainingLinks.length === 0 || remainingLinks.length !== remainingUrls.length) return 0;

        let added = 0;
        debugLog('log', `${LOG_PREFIX} 剩余数量相同，按顺序对应`);
        for (let i = 0; i < remainingLinks.length; i++) {
            if (addMapping(remainingLinks[i].href, remainingUrls[i].url, '剩余顺序匹配')) {
                usedUrls.add(remainingUrls[i].url);
                added++;
            }
        }
        return added;
    }

    function buildMapping(jsonContent, htmlContent, sourceName = '内容') {
        const jsonUrls = extractJsonUrls(jsonContent);
        const externalLinks = extractExternalLinks(htmlContent);
        let added = 0;
        
        debugLog('log', LOG_PREFIX, sourceName, 'URL数量:', jsonUrls.length, 'HTML external数量:', externalLinks.length);
        if (jsonUrls.length === 0 || externalLinks.length === 0) {
            return 0;
        }
        
        // 策略1: 数量相同，按顺序对应
        if (jsonUrls.length === externalLinks.length) {
            debugLog('log', `${LOG_PREFIX} 数量相同，按顺序对应`);
            for (let i = 0; i < externalLinks.length; i++) {
                if (addMapping(externalLinks[i].href, jsonUrls[i].url, '顺序匹配')) {
                    added++;
                }
            }
        } else {
            // 策略2: 数量不同，用域名和剩余顺序匹配
            debugLog('log', `${LOG_PREFIX} 数量不同，使用域名/上下文/剩余顺序匹配`);
            const usedUrls = new Set();

            added += addUniqueDomainMappings(externalLinks, jsonUrls, usedUrls);
            added += addContextMappings(externalLinks, jsonUrls, usedUrls);
            added += addRemainingOrderMappings(externalLinks, jsonUrls, usedUrls);

            for (const ext of externalLinks) {
                if (!urlMap[ext.href]) {
                    debugLog('log', `${LOG_PREFIX} 未匹配:`, ext.href, ext.text || '');
                }
            }
        }
        
        debugLog('log', `${LOG_PREFIX} === 匹配完成，共`, Object.keys(urlMap).length, '条 ===');
        return added;
    }

    function resetMappingRetryState() {
        mappingRetryState = { postId: null, signature: '', attempts: 0, stopped: false };
    }

    function getMappingRetrySignature(postId) {
        const externalHrefs = getCurrentExternalHrefs().join('|');
        const cachedContent = getCachedRawContent(postId);
        return `${postId}:${externalHrefs}:${cachedContent.length}`;
    }

    function isMappingRetryStopped(postId) {
        const signature = getMappingRetrySignature(postId);
        return mappingRetryState.postId === postId
            && mappingRetryState.signature === signature
            && mappingRetryState.stopped;
    }

    function recordMappingRetryResult(postId, added) {
        const signature = getMappingRetrySignature(postId);
        if (mappingRetryState.postId !== postId || mappingRetryState.signature !== signature) {
            mappingRetryState = { postId, signature, attempts: 0, stopped: false };
        }

        if (added > 0) {
            mappingRetryState.attempts = 0;
            mappingRetryState.stopped = false;
            return;
        }

        mappingRetryState.attempts++;
        if (mappingRetryState.attempts >= MAX_MAPPING_RETRY_WITHOUT_PROGRESS) {
            mappingRetryState.stopped = true;
            debugLog('warn', `${LOG_PREFIX} 直链补匹配连续无新增，停止本轮懒加载重试`);
        }
    }

    function cacheRawContent(postId, content) {
        if (!postId || !content) return;

        if (rawContentCache.postId !== postId) {
            rawContentCache = { postId, content: '' };
        }

        if (!rawContentCache.content.includes(content)) {
            rawContentCache.content = rawContentCache.content
                ? `${rawContentCache.content}\n${content}`
                : content;
            resetMappingRetryState();
        }
    }

    function getCachedRawContent(postId) {
        return rawContentCache.postId === postId ? rawContentCache.content : '';
    }

    function getCurrentExternalHrefs() {
        const hrefs = Array.from(document.querySelectorAll('a[href*="external?e="]'))
            .map(link => normalizeExternalHref(link.getAttribute('href') || link.href))
            .filter(Boolean);
        return [...new Set(hrefs)];
    }

    function hasUnmappedExternalLinks() {
        return getCurrentExternalHrefs().some(href => !urlMap[href]);
    }

    function buildMappingFromCache(sourceName) {
        const postId = getPostId();
        const cachedContent = getCachedRawContent(postId);
        if (!cachedContent || !hasUnmappedExternalLinks()) return 0;
        if (isMappingRetryStopped(postId)) return 0;

        const added = buildMapping(cachedContent, getRenderedContentHtml(), sourceName);
        recordMappingRetryResult(postId, added);
        return added;
    }

    function scheduleMappingFromDom(delay = 300) {
        clearTimeout(mappingRetryTimer);
        mappingRetryTimer = setTimeout(() => {
            mappingRetryTimer = null;
            const postId = getPostId();
            if (!postId) return;

            if (getCachedRawContent(postId)) {
                if (!isMappingRetryStopped(postId)) {
                    buildMappingFromCache('懒加载DOM');
                }
            } else if (!isLoading && getCurrentExternalHrefs().length > 0) {
                loadMappings();
            }
        }, delay);
    }

    // 页面监听：兼容 Nuxt 路由切换和瀑布流懒加载，新增内容后重新扫描。
    function startContentObserver() {
        if (mutationObserver || !document.body) return;

        mutationObserver = new MutationObserver(mutations => {
            const changed = mutations.some(mutation => mutation.addedNodes && mutation.addedNodes.length > 0);
            if (changed && getPostId()) {
                scheduleMappingFromDom();
            }
            if (changed) {
                schedulePreviewProcessing();
            }
        });
        mutationObserver.observe(document.body, { childList: true, subtree: true });
    }

    function getRenderedContentHtml() {
        const prose = document.querySelector('.prose');
        if (prose && prose.querySelector('a[href*="external?e="]')) {
            return prose.innerHTML;
        }

        return document.body.innerHTML;
    }

    function extractPageRawContents() {
        const script = document.querySelector('#__NUXT_DATA__');
        if (!script || !script.textContent) return [];

        try {
            const payload = JSON.parse(script.textContent);
            if (!Array.isArray(payload)) return [];

            const contents = [];
            const seen = new Set();
            for (const value of payload) {
                if (typeof value !== 'string') continue;
                if (!/https?:\/\//i.test(value)) continue;
                if (!/<\s*(?:a|p|br|div|span|strong|h[1-6]|hidden_content)/i.test(value)) continue;

                const content = value.trim();
                if (content && !seen.has(content)) {
                    seen.add(content);
                    contents.push(content);
                }
            }

            debugLog('log', `${LOG_PREFIX} Nuxt数据中找到内容段:`, contents.length);
            return contents;
        } catch (e) {
            debugLog('warn', `${LOG_PREFIX} Nuxt数据解析失败:`, e);
            return [];
        }
    }

    async function loadMappings() {
        const postId = getPostId();
        if (!postId) {
            clearMappings();
            return;
        }

        if (isLoading) return;
        isLoading = true;

        if (mappedPostId !== postId) {
            clearMappings();
            mappedPostId = postId;
        }

        debugLog('log', `${LOG_PREFIX} 加载文章ID:`, postId);
        let mappedCount = 0;
        try {
            const htmlContent = getRenderedContentHtml();
            const pageContents = extractPageRawContents();
            if (pageContents.length > 0) {
                cacheRawContent(postId, pageContents.join('\n'));
                mappedCount += buildMapping(getCachedRawContent(postId), htmlContent, 'Nuxt数据');
            }

            const apiContent = await fetchPostContent(postId);
            if (getPostId() === postId) {
                cacheRawContent(postId, apiContent);
                mappedCount += buildMapping(getCachedRawContent(postId), getRenderedContentHtml(), 'API数据');
            } else {
                debugLog('log', `${LOG_PREFIX} 页面已切换，忽略旧API响应:`, postId);
            }
        } catch (e) {
            if (mappedCount > 0) {
                debugLog('warn', `${LOG_PREFIX} API加载失败，已使用页面数据完成部分映射:`, e);
            } else {
                debugLog('error', `${LOG_PREFIX} 加载失败:`, e);
            }
        }
        isLoading = false;

        if (getCachedRawContent(postId) && hasUnmappedExternalLinks() && !isMappingRetryStopped(postId)) {
            scheduleMappingFromDom(800);
        } else if (getCachedRawContent(postId) && getCurrentExternalHrefs().length === 0) {
            debugLog('log', `${LOG_PREFIX} 当前DOM未找到external，等待懒加载内容渲染`);
        }

        const currentPostId = getPostId();
        if (currentPostId && currentPostId !== mappedPostId) {
            setTimeout(loadMappings, 0);
        }
    }

    async function resolveRealUrl(href) {
        if (urlMap[href]) return urlMap[href];

        const postId = getPostId();
        if (!postId) return '';

        if (getCachedRawContent(postId)) {
            buildMappingFromCache('点击前补映射');
            if (urlMap[href]) return urlMap[href];
            if (isMappingRetryStopped(postId)) return '';
        }

        if (!isLoading) {
            await loadMappings();
            if (urlMap[href]) return urlMap[href];
        }

        scheduleMappingFromDom(500);
        return '';
    }

    async function handleClick(e) {
        const link = e.target.closest('a[href*="external?e="]');
        if (!link) return;

        const href = normalizeExternalHref(link.getAttribute('href') || link.href);
        const realUrl = urlMap[href];

        e.preventDefault();
        e.stopPropagation();

        if (realUrl) {
            debugLog('log', `${LOG_PREFIX} 直链跳转:`, realUrl);
            window.open(realUrl, '_blank', 'noopener');
        } else {
            const resolvedUrl = await resolveRealUrl(href);
            if (resolvedUrl) {
                debugLog('log', `${LOG_PREFIX} 直链跳转:`, resolvedUrl);
                window.open(resolvedUrl, '_blank', 'noopener');
                return;
            }

            const fallbackUrl = link.href || new URL(href, window.location.origin).href;
            debugLog('warn', `${LOG_PREFIX} 未找到映射，打开原external链接:`, fallbackUrl);
            showToast('暂未找到对应直链，已打开原站跳转链接', 'warning');
            window.open(fallbackUrl, '_blank', 'noopener');
        }
    }

    // 调试入口：在控制台使用 vikacgEnhanced.* 查看签到、预览和日志状态。
    function exposeDebugTools() {
        const target = typeof unsafeWindow !== 'undefined' ? unsafeWindow : window;
        target.vikacgEnhanced = {
            signNow: runDailySign,
            resetSignState() {
                gmSet(SIGN_STATE_KEY, {});
                showToast('已清空签到防重复状态，可重新尝试签到', 'info');
                debugLog('log', `${LOG_PREFIX} 已清空签到防重复状态`);
            },
            signStatus() {
                const tokenInfo = getAuthTokenInfo();
                const status = {
                    script: '维咔ACG增强',
                    version: '2.0',
                    signApi: `${getApiBase()}/api/vikacg/v1/userMission`,
                    hasToken: Boolean(tokenInfo.token),
                    tokenSource: tokenInfo.source || '',
                    tokenLength: tokenInfo.token ? tokenInfo.token.length : 0,
                    state: tokenInfo.token ? getSignState(tokenInfo.token).userState : null,
                };
                debugLog('log', `${LOG_PREFIX} 签到状态:`, status);
                showToast(status.hasToken ? `已找到 authorization：${status.tokenSource}` : '未找到 authorization', status.hasToken ? 'success' : 'warning');
                return status;
            },
            toast(message = 'toast 测试') {
                showToast(message, 'info');
            },
            previewStatus() {
                const status = {
                    count: getPreviewCount(),
                    concurrent: getPreviewMaxConcurrent(),
                    logLevel: getLogConsoleLevel(),
                    recommendKeywords: getRecommendKeywords(),
                    pending: previewPending,
                    queued: previewQueue.length,
                    candidates: getPostListLinks().length,
                    cards: document.querySelectorAll('.vikacg-enhanced-preview').length,
                };
                debugLog('log', `${LOG_PREFIX} 预览状态:`, status);
                showToast(`预览图片数：${status.count}，并发：${status.concurrent}`, 'info');
                return status;
            },
            logs() {
                const logs = getPageWindow().__vikacgEnhancedLogs || [];
                debugLog('log', `${LOG_PREFIX} 最近日志:`, logs.slice(-50));
                return logs;
            },
            setPreviewCount(count = PREVIEW_DEFAULT_COUNT) {
                const next = clampNumber(count, PREVIEW_DEFAULT_COUNT, 0, PREVIEW_MAX_COUNT);
                gmSet(PREVIEW_COUNT_KEY, next);
                resetPreviewDom();
                schedulePreviewProcessing(0);
                showToast(next > 0 ? `预览图片数已设置为 ${next}` : '已关闭列表预览增强', 'info');
                return next;
            },
            setLogLevel(level = 'warn') {
                const next = String(level || 'warn').toLowerCase();
                if (!Object.prototype.hasOwnProperty.call(LOG_LEVELS, next)) {
                    showToast('日志等级无效，可用：debug/log/warn/error/silent', 'warning');
                    return getLogConsoleLevel();
                }
                gmSet(LOG_LEVEL_KEY, next);
                showToast(`日志等级已设置为 ${next}`, 'info');
                return next;
            },
            setRecommendKeywords(keywords = DEFAULT_RECOMMEND_KEYWORDS) {
                const list = Array.isArray(keywords)
                    ? keywords
                    : String(keywords || '').split(/[,，\s]+/);
                const next = list.map(item => String(item || '').trim()).filter(Boolean);
                gmSet(RECOMMEND_KEYWORDS_KEY, next.length ? next : DEFAULT_RECOMMEND_KEYWORDS);
                schedulePreviewProcessing(0);
                showToast(`推荐屏蔽关键词：${getRecommendKeywords().join('、')}`, 'info');
                return getRecommendKeywords();
            },
            clearPreviewCache() {
                return clearPreviewCacheAndRefresh();
            },
            clearAuthCache() {
                gmDelete(AUTH_HEADER_KEY);
                showToast('已清理 authorization 缓存，刷新或触发站内请求后会重新捕获', 'info');
                return true;
            },
        };
    }

    function registerMenuCommands() {
        if (typeof GM_registerMenuCommand !== 'function') return;

        GM_registerMenuCommand('删除图片缓存', () => {
            clearPreviewCacheAndRefresh();
        });
    }

    function startApp() {
        if (appStarted) return;
        appStarted = true;
        debugLog('log', `${LOG_PREFIX} 启动增强功能:`, {
            route: getRouteKey(),
            readyState: document.readyState,
            previewCount: getPreviewCount(),
            previewConcurrent: getPreviewMaxConcurrent(),
        });

        loadMappings();
        schedulePreviewProcessing(500);
        setTimeout(runDailySign, 2000);
        startContentObserver();
        document.addEventListener('click', handleClick, true);

        setInterval(() => {
            const currentRoute = getRouteKey();
            if (currentRoute !== routePath) {
                routePath = currentRoute;
                clearMappings();
                setTimeout(loadMappings, 500);
                setTimeout(runDailySign, 2000);
                scheduleMappingFromDom(1200);
                schedulePreviewProcessing(800);
            }
        }, 1000);
    }

    installAuthorizationCapture();
    exposeDebugTools();
    registerMenuCommands();
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', startApp, { once: true });
    } else {
        startApp();
    }
})();