// ==UserScript==
// @name         nhentai 漫画下拉阅读模式（2026 新版修复）
// @namespace    https://github/FENGLIAA
// @version      0.5.3
// @description  适配 nhentai.net 2026 改版（SvelteKit + v2 API + 新 CDN），支持 nhentai.xxx 与 e-hentai；多节点自动容错 + 超时切换 + 调试日志
// @author       FENGLIAA
// @license      MIT
// @match        https://nhentai.net/g/*
// @match        https://nhentai.xxx/g/*
// @match        https://e-hentai.org/g/*
// @match        https://e-hentai.org/s/*
// @match        https://exhentai.org/g/*
// @match        https://exhentai.org/s/*
// @grant        GM_xmlhttpRequest
// @grant        GM_addStyle
// @grant        unsafeWindow
// @run-at       document-idle
// ==/UserScript==

// 为什么旧版会裂图：
// nhentai.net 2026-03 末大改版（SvelteKit 重写）——
//   1) 旧接口 api/gallery/{id} 与页面结构 #thumbnail-container a 失效；
//   2) 图片 CDN 从裸 i.nhentai.net 改为 i1-i4.nhentai.net（裸 i. 经常失败）；
//   3) 逐页抓 HTML 撞上 Cloudflare，拿到挑战页解析不到图片。
// 新版改为：直接读页面内嵌的画廊 JSON（零请求），图片用原生 <img> 加载（浏览器自带
// cf 通行凭证），再配 i1-i4 多节点 onerror 自动切换，几乎不会再裂。

(function () {
  'use strict';

  const HOST = location.hostname;
  const IS_NHENTAI = HOST === 'nhentai.net';
  const IS_XXX = HOST === 'nhentai.xxx';
  const IS_EH = HOST === 'e-hentai.org' || HOST === 'exhentai.org';
  if (!IS_NHENTAI && !IS_XXX && !IS_EH) return;

  /* ---------- 调试日志（F12 控制台过滤 [nh-read] 查看） ---------- */
  const DEBUG = true;
  const LOG_DETAIL = 8; // 前 8 页详细记录每次请求/超时/报错，其余页只记最终失败
  function dbg(...args) { if (DEBUG) console.log('[nh-read]', ...args); }

  /* ---------- 工具 ---------- */

  const sleep = ms => new Promise(r => setTimeout(r, ms));

  function gmGetText(url, timeoutMs) {
    return new Promise((resolve, reject) => {
      GM_xmlhttpRequest({
        method: 'GET',
        url,
        timeout: timeoutMs || 20000,
        onload: r => {
          if (r.status >= 200 && r.status < 300) resolve(r.responseText);
          else reject(new Error('HTTP ' + r.status + ': ' + url));
        },
        onerror: () => reject(new Error('网络错误: ' + url)),
        ontimeout: () => reject(new Error('超时: ' + url)),
      });
    });
  }

  function parseDoc(html) {
    return new DOMParser().parseFromString(html, 'text/html');
  }

  // 并发受限队列（e-hentai 抓页用，避免触发限流）
  function makeQueue(limit) {
    let running = 0;
    const waiters = [];
    const next = () => {
      if (running >= limit || !waiters.length) return;
      running += 1;
      waiters.shift()();
    };
    return fn => new Promise((res, rej) => {
      waiters.push(async () => {
        try { res(await fn()); } catch (e) { rej(e); }
        running -= 1;
        next();
      });
      next();
    });
  }

  /* ---------- 数据源 ---------- */

  // 新 nhentai.net：详情页内嵌画廊 JSON（SvelteKit 水合数据）
  function readEmbeddedGallery() {
    const w = (typeof unsafeWindow !== 'undefined' ? unsafeWindow : null) || window;
    let g = null;
    try { g = w._gallery || w.gallery; } catch (e) { /* ignore */ }
    if (g && g.media_id && Array.isArray(g.pages) && g.pages.length) return normGallery(g);

    const script = document.querySelector('script[data-sveltekit-fetched][data-url^="/api/v2/galleries/"]');
    if (script) {
      try {
        const obj = JSON.parse(script.textContent);
        let body = obj && obj.body !== undefined ? obj.body : obj;
        if (typeof body === 'string') body = JSON.parse(body);
        if (body && body.media_id && Array.isArray(body.pages) && body.pages.length) return normGallery(body);
      } catch (e) { /* ignore */ }
    }
    return null;
  }

  function normGallery(g) {
    return {
      mediaId: g.media_id,
      paths: g.pages.map(p => (p && p.path) ? p.path : (p && p.number ? p.number + '.jpg' : '')),
    };
  }

  // 旧版结构回退：缩略图 URL → 原图 URL（t{n}→i{n}，去掉页号后的 t）
  function deriveFromThumbs() {
    const map = new Map();
    document.querySelectorAll('#thumbnail-container img').forEach(img => {
      const src = img.getAttribute('data-src') || img.getAttribute('src') || img.src || '';
      const m = /\/galleries\/[^/?#]+\/(\d+)t?\.([a-z0-9]+)$/i.exec(src);
      if (!m) return;
      const n = parseInt(m[1], 10);
      if (!n || map.has(n)) return;
      map.set(n, src
        .replace(/\/\/t(\d*)\.nhentai\./i, '//i$1.nhentai.')
        .replace(/(\d+)t\.([a-z0-9]+)$/i, '$1.$2'));
    });
    if (!map.size) return null;
    const out = [];
    map.forEach((url, n) => { out[n - 1] = url; });
    return out;
  }

  // 最后手段：从当前阅读页的大图 URL 推导全部页
  function deriveFromViewerImg() {
    let src = '';
    document.querySelectorAll(IS_XXX ? '#fimg' : '#image-container img').forEach(el => {
      if (!src) src = el.getAttribute('data-src') || el.getAttribute('src') || el.src || '';
    });
    const m = src.match(/^(https?:\/\/.+\/galleries\/[^/]+\/)\d+\.([a-z0-9]+)$/i);
    if (!m) return null;
    const txt = document.body.innerText || '';
    const mm = txt.match(/(\d+)\s*pages?/i);
    const total = mm ? parseInt(mm[1], 10) : 0;
    if (!total || total > 2000) return null;
    const out = [];
    for (let n = 1; n <= total; n += 1) out.push(m[1] + n + '.' + m[2]);
    return out;
  }

  // 图片节点列表：优先 /api/v2/config，失败则用默认 i1-i4/i5/i7/i 全部兜底
  let serverListPromise = null;
  function getServerList() {
    if (!serverListPromise) {
      serverListPromise = (async () => {
        const list = [];
        try {
          const cfg = JSON.parse(await gmGetText('https://nhentai.net/api/v2/config', 8000));
          if (cfg && Array.isArray(cfg.image_servers)) {
            cfg.image_servers.forEach(s => { if (s && typeof s === 'string') list.push(s); });
          }
        } catch (e) { /* 用默认节点 */ }
        ['i1', 'i2', 'i3', 'i4', 'i5', 'i7', 'i'].forEach(h => {
          const host = h + '.nhentai.net';
          if (!list.some(s => String(s).indexOf(host) !== -1)) list.push('https://' + host);
        });
        return list;
      })();
    }
    return serverListPromise;
  }

  // 兼容多种写法：
  // server: i1.nhentai.net / https://i1.nhentai.net/galleries/{id}
  // path:   1.jpg 或 galleries/{media_id}/1.jpg（v2 API 实际返回自带前缀的路径）
  function buildImageUrl(server, mediaId, path) {
    let s = String(server || '').trim().replace(/\/+$/, '');
    if (!s) return '';
    if (!/^https?:\/\//i.test(s)) s = 'https://' + s;
    const p = String(path || '').replace(/^\/+/, '');
    if (!p) return '';
    if (/^galleries\//i.test(p)) return s + '/' + p;
    if (/\/galleries\/[^/]+$/i.test(s)) return s + '/' + p;
    if (/\/galleries\/?$/i.test(s)) return s + '/' + mediaId + '/' + p;
    return s + '/galleries/' + mediaId + '/' + p;
  }

  // e-hentai：由 sha/gid 生成 1..total 的阅读页地址
  function ehGetPages() {
    const path = location.pathname;
    const mG = path.match(/^\/g\/(\d+)\/([0-9a-f]+)/i);
    const mS = path.match(/^\/s\/([0-9a-f]+)\/(\d+)-\d+/i);
    const gid = mS ? mS[2] : (mG ? mG[1] : null);
    let sha = mS ? mS[1] : null;
    if (!gid) return null;
    if (!sha) {
      const a = document.querySelector('#gdt a');
      const m = a && (a.getAttribute('href') || '').match(/\/s\/([0-9a-f]+)\//i);
      if (!m) return null;
      sha = m[1];
    }
    const txt = document.body.innerText || '';
    const mm = txt.match(/Length:\s*(\d+)\s*pages/i)
      || txt.match(/Pages:\s*(\d+)/i)
      || txt.match(/Showing\s+[\d,\s–-]*of\s+(\d+)\s+images/i);
    let total = mm ? parseInt(mm[1], 10) : 0;
    if (!total) total = document.querySelectorAll('#gdt a').length;
    if (!total || total > 3000) return null;
    const out = [];
    for (let n = 1; n <= total; n += 1) out.push('https://' + HOST + '/s/' + sha + '/' + gid + '-' + n);
    return out;
  }

  /* ---------- 数据汇总 ---------- */

  async function resolvePages() {
    if (IS_NHENTAI) {
      // 1) 页面内嵌 JSON（等 SvelteKit 水合，最多约 5 秒）
      for (let i = 0; i < 15; i += 1) {
        const g = readEmbeddedGallery();
        if (g) {
          const servers = await getServerList();
          return { kind: 'nh', mediaId: g.mediaId, pages: g.paths, servers };
        }
        await sleep(350);
      }
      // 2) 缩略图回退
      const thumbs = deriveFromThumbs();
      if (thumbs) return { kind: 'direct', pages: thumbs };
      // 3) v2 API
      const gid = (location.pathname.match(/\/g\/(\d+)/) || [])[1];
      if (gid) {
        try {
          const api = JSON.parse(await gmGetText('https://nhentai.net/api/v2/galleries/' + gid, 15000));
          if (api && api.media_id && Array.isArray(api.pages) && api.pages.length) {
            const servers = await getServerList();
            return { kind: 'nh', mediaId: api.media_id, pages: api.pages.map(p => p.path || ''), servers };
          }
        } catch (e) { /* ignore */ }
      }
      // 4) 阅读页大图推导
      const list = deriveFromViewerImg();
      if (list) return { kind: 'direct', pages: list };
      return null;
    }

    if (IS_XXX) {
      // 详情页缩略图链接 → 懒加载逐页抓 #fimg
      const links = Array.from(document.querySelectorAll('.gt_th > a'));
      if (links.length) {
        return { kind: 'fetch', pages: links.map(a => ({ href: a.href, selector: '#fimg' })) };
      }
      const list = deriveFromViewerImg();
      if (list) return { kind: 'direct', pages: list };
      return null;
    }

    if (IS_EH) {
      const pages = ehGetPages();
      if (pages) return { kind: 'fetch', pages: pages.map(href => ({ href, selector: '#img' })) };
      return null;
    }

    return null;
  }

  /* ---------- UI ---------- */

  GM_addStyle([
    '#nh-read-mode { position: fixed; top: 0; left: 0; width: 100%; height: 100%;',
    '  background: #000; overflow-y: scroll; z-index: 2147483000; display: none; text-align: center; }',
    '#nh-read-mode img { width: 90%; max-width: 800px; margin: 20px auto; display: block;',
    '  background: #161616; min-height: 60px; }',
    '#nh-read-mode img[data-state="loading"] { height: 420px; object-fit: contain; }',
    '#nh-read-status { position: fixed; top: 12px; left: 50%; transform: translateX(-50%);',
    '  z-index: 2147483001; background: rgba(0,0,0,.85); color: #fff; padding: 6px 14px;',
    '  border-radius: 14px; font: 13px/1.5 sans-serif; display: none; max-width: 90%; text-align: center; }',
    '#nh-read-close { position: fixed; top: 10px; right: 10px; z-index: 2147483002;',
    '  padding: 6px 12px; background: #e74c3c; color: #fff; border: none; border-radius: 4px;',
    '  cursor: pointer; display: none; font-size: 14px; }',
    '#nh-read-open { position: fixed; bottom: 20px; right: 20px; z-index: 2147483002;',
    '  padding: 10px 14px; background: #27ae60; color: #fff; border: none; border-radius: 4px;',
    '  cursor: pointer; font-size: 14px; box-shadow: 0 2px 8px rgba(0,0,0,.4); }'
  ].join('\n'));

  const box = document.createElement('div');
  box.id = 'nh-read-mode';
  document.body.appendChild(box);

  const statusEl = document.createElement('div');
  statusEl.id = 'nh-read-status';
  document.body.appendChild(statusEl);

  const closeBtn = document.createElement('button');
  closeBtn.id = 'nh-read-close';
  closeBtn.textContent = '✖ 关闭阅读';
  closeBtn.onclick = hideReader;
  document.body.appendChild(closeBtn);

  const openBtn = document.createElement('button');
  openBtn.id = 'nh-read-open';
  openBtn.textContent = '📖 下拉阅读';
  openBtn.onclick = () => { showReader(); loadReader(); };
  document.body.appendChild(openBtn);

  let state = 'idle'; // idle | loading | done | error
  const fetchQueue = makeQueue(2);

  function showReader() {
    box.style.display = 'block';
    closeBtn.style.display = 'block';
    openBtn.style.display = 'none';
  }

  function hideReader() {
    box.style.display = 'none';
    closeBtn.style.display = 'none';
    openBtn.style.display = 'block';
    setStatus(null);
  }

  function setStatus(text) {
    if (!text) { statusEl.style.display = 'none'; return; }
    statusEl.textContent = text;
    statusEl.style.display = 'block';
  }

  document.addEventListener('keydown', e => {
    if (e.key === 'Escape' && box.style.display === 'block') hideReader();
  });

  /* ---------- 渲染 ---------- */

  async function loadReader() {
    if (state === 'loading' || state === 'done') return;
    state = 'loading';
    setStatus('正在解析页面…');
    let data = null;
    try { data = await resolvePages(); } catch (e) { dbg('resolvePages 异常:', e && e.message); data = null; }
    if (!data || !data.pages || !data.pages.length) {
      state = 'error';
      dbg('没找到图片数据');
      setStatus('❌ 没找到图片数据：请在本子【详情页】打开再点“下拉阅读”；若仍失败可能是网络/Cloudflare 拦截，稍后重试。');
      return;
    }
    dbg('数据源 kind=' + data.kind + ' 页数=' + data.pages.length +
      ' mediaId=' + (data.mediaId || '-') +
      ' servers=' + ((data.servers || []).slice(0, 4).join(', ') || '-'));
    if (data.kind === 'nh' && data.servers && data.servers.length && data.pages[0]) {
      dbg('第一页 URL 示例:', buildImageUrl(data.servers[0], data.mediaId, data.pages[0]));
    }
    renderPages(data);
    state = 'done';
    setStatus(null);
  }

  function renderPages(data) {
    box.innerHTML = '';
    const frag = document.createDocumentFragment();
    data.pages.forEach((p, i) => frag.appendChild(createPageItem(data, p, i)));
    box.appendChild(frag);
  }

  // 逐节点尝试加载：加载失败或 10 秒超时都会切换下一个 CDN 节点
  function applyServerChain(img, servers, mediaId, path, i) {
    let idx = 0;
    let settled = false;
    let timer = null;
    function next() {
      if (settled) return;
      idx += 1;
      if (idx < servers.length) {
        tryServer(idx);
      } else {
        settled = true;
        clearTimeout(timer);
        img.alt = '图片加载失败 (第 ' + (i + 1) + ' 页)：所有节点都失败。若官网阅读页能看图，请检查代理是否放行 i*.nhentai.net';
        dbg('P' + (i + 1) + ' 全部节点失败');
      }
    }
    function tryServer(k) {
      if (settled) return;
      clearTimeout(timer);
      img.src = buildImageUrl(servers[k], mediaId, path);
      if (i < LOG_DETAIL) dbg('P' + (i + 1) + ' 请求 ' + servers[k]);
      timer = setTimeout(() => {
        if (i < LOG_DETAIL) dbg('P' + (i + 1) + ' 超时(10s) ' + servers[k] + '，切换下一个');
        next();
      }, 10000);
    }
    img.onerror = () => {
      if (!settled) {
        if (i < LOG_DETAIL) dbg('P' + (i + 1) + ' 报错 ' + servers[idx] + '，切换下一个');
        next();
      }
    };
    img.onload = () => {
      settled = true;
      clearTimeout(timer);
      img.alt = '';
      if (i < LOG_DETAIL) dbg('P' + (i + 1) + ' 加载成功 ' + servers[idx]);
    };
    tryServer(0);
  }

  function createPageItem(data, p, i) {
    const img = document.createElement('img');
    img.decoding = 'async';
    if (data.kind === 'nh') {
      // nhentai：立即加载（不用 loading=lazy，固定滚动容器里可能永远不触发请求），
      // 失败或超时自动切换 CDN 节点
      applyServerChain(img, data.servers, data.mediaId, p, i);
    } else if (data.kind === 'direct') {
      img.src = p;
      if (i < LOG_DETAIL) dbg('P' + (i + 1) + ' direct ' + p);
      img.onerror = () => { img.alt = '图片加载失败 (第 ' + (i + 1) + ' 页)'; dbg('P' + (i + 1) + ' direct 报错'); };
      setTimeout(() => {
        if (!img.complete || !img.naturalWidth) {
          img.alt = '图片加载超时 (第 ' + (i + 1) + ' 页)，节点可能被墙';
          dbg('P' + (i + 1) + ' direct 超时(20s)');
        }
      }, 20000);
    } else {
      // e-hentai / nhentai.xxx：滚动到附近才抓页
      img.dataset.state = 'loading';
      img.alt = '加载中 (第 ' + (i + 1) + ' 页)…';
      observeLazy(img, p);
    }
    return img;
  }

  /* ---------- 懒加载抓页 ---------- */

  let io = null;
  function observeLazy(img, p) {
    if (!('IntersectionObserver' in window)) { loadPageInto(img, p); return; }
    if (!io) {
      io = new IntersectionObserver(entries => {
        entries.forEach(en => {
          if (en.isIntersecting) {
            io.unobserve(en.target);
            loadPageInto(en.target, JSON.parse(en.target.dataset.page));
          }
        });
      }, { root: box, rootMargin: '800px 0px' });
    }
    img.dataset.page = JSON.stringify(p);
    io.observe(img);
  }

  function loadPageInto(img, p) {
    if (img.dataset.state !== 'loading') return;
    fetchQueue(async () => {
      for (let attempt = 1; attempt <= 4; attempt += 1) {
        try {
          const html = await gmGetText(p.href, 30000);
          const doc = parseDoc(html);
          const el = doc.querySelector(p.selector);
          const raw = el && (el.getAttribute('data-src') || el.getAttribute('src') || el.src);
          if (!raw) throw new Error('no img');
          img.src = /^https?:/i.test(raw) ? raw : new URL(raw, p.href).href;
          img.onload = () => { img.dataset.state = 'done'; img.alt = ''; dbg('fetch 成功 ' + p.href); };
          img.onerror = () => { img.dataset.state = 'failed'; img.alt = '图片加载失败'; dbg('fetch 图片加载失败 ' + p.href); };
          return;
        } catch (err) {
          dbg('fetch 抓页失败 attempt=' + attempt + ' ' + p.href, (err && err.message) || err);
          await sleep(1200 * attempt);
        }
      }
      img.dataset.state = 'failed';
      img.alt = '加载失败（可能被限流），点击重试';
      img.style.cursor = 'pointer';
      img.onclick = () => {
        img.dataset.state = 'loading';
        img.alt = '加载中…';
        img.onclick = null;
        loadPageInto(img, p);
      };
    });
  }
})();