// ==UserScript==
// @name         文档批量下载器 (VitePress + VuePress)
// @namespace    https://github.com/ai-assistant/document-downloader
// @version      0.2.0
// @description  通用 VitePress/VuePress 文档批量下载，直接抓取 .md 源码，保存到本地文件夹
// @author       AI Assistant
// @match        *://*/*
// @grant        GM_notification
// @grant        GM_download
// @run-at       document-idle
// ==/UserScript==

(function() {
  'use strict';

  // ==================== 配置 ====================
  var CONFIG = {
    DELAY: 150,          // 请求间隔 (ms)
    TIMEOUT: 20000,      // 单个请求超时 (ms)
    MAX_RETRY: 3,        // 最大重试次数
    RETRY_DELAY: 1000    // 重试间隔 (ms)
  };

  var SITE_TYPE = null;   // 'vitepress' 或 'vuepress'
  var CURRENT_FOLDER = null;
  var BASE_URL = '';

  // ==================== 工具函数 ====================
  function log(msg, data) {
    console.log('[DocDL]', msg, data || '');
  }

  function delay(ms) {
    return new Promise(function(r) { setTimeout(r, ms); });
  }

  // ==================== 站点检测 ====================
  function detectSiteType() {
    // 检测 VitePress
    if (document.documentElement.outerHTML.indexOf('__VP_HASH_MAP__') > -1 ||
        document.documentElement.outerHTML.indexOf('vitepress') > -1 ||
        document.querySelector('meta[name="generator"][content*="VitePress"]') ||
        document.querySelector('.VPSidebar')) {
      return 'vitepress';
    }
    
    // 检测 VuePress
    if (document.querySelector('meta[name="generator"][content*="VuePress"]') ||
        document.querySelector('.vp-sidebar') ||
        document.querySelector('.theme-hope-content')) {
      return 'vuepress';
    }
    
    return null;
  }

  // ==================== 提取页面列表 ====================
  function extractPages() {
    if (SITE_TYPE === 'vitepress') {
      return extractVitePressPages();
    } else if (SITE_TYPE === 'vuepress') {
      return extractVuePressPages();
    }
    return [];
  }

  // VitePress 页面提取
  function extractVitePressPages() {
    var pages = [];
    var seen = new Set();
    var groups = document.querySelectorAll('.VPSidebarItem.level-0');

    if (groups.length) {
      groups.forEach(function(g) {
        var folderEl = g.querySelector(':scope > .item > .text');
        var folder = folderEl ? folderEl.textContent.trim() : '';
        var links = g.querySelectorAll('.VPSidebarItem.level-1.is-link a[href]');

        links.forEach(function(a) {
          var href = a.getAttribute('href');
          var titleEl = a.querySelector('.text');
          var title = titleEl ? titleEl.textContent.trim() : '';

          if (href && !seen.has(href)) {
            seen.add(href);
            pages.push({ title: title, url: href, folder: folder });
          }
        });
      });
    } else {
      var sidebar = document.querySelector('.VPSidebar nav') || document.querySelector('aside nav');
      if (sidebar) {
        sidebar.querySelectorAll('a[href]').forEach(function(a) {
          var href = a.getAttribute('href');
          if (href && !seen.has(href) && href !== '#' && !href.startsWith('http')) {
            seen.add(href);
            pages.push({ title: a.textContent.trim(), url: href, folder: '' });
          }
        });
      }
    }

    log('VitePress 提取到 ' + pages.length + ' 个页面');
    return pages;
  }

  // VuePress 页面提取
  function extractVuePressPages() {
    var pages = [];
    var seen = new Set();
    
    // VuePress Theme Hope 侧边栏结构
    var sidebarGroups = document.querySelectorAll('.vp-sidebar-links > li');
    
    if (sidebarGroups.length) {
      sidebarGroups.forEach(function(group) {
        // 获取一级标题（如 "一、前言"）
        var topLink = group.querySelector(':scope > .vp-sidebar-link');
        var topFolder = topLink ? topLink.textContent.trim() : '';
        
        if (topLink && topLink.getAttribute('href') && !seen.has(topLink.getAttribute('href'))) {
          seen.add(topLink.getAttribute('href'));
          pages.push({ 
            title: topLink.textContent.trim(), 
            url: topLink.getAttribute('href'), 
            folder: '' 
          });
        }
        
        // 获取子菜单
        var subGroups = group.querySelectorAll(':scope > .vp-sidebar-group');
        subGroups.forEach(function(subGroup) {
          var groupTitleEl = subGroup.querySelector(':scope > .vp-sidebar-header .vp-sidebar-title');
          var groupTitle = groupTitleEl ? groupTitleEl.textContent.trim() : '';
          
          // 如果标题是链接
          var groupLink = subGroup.querySelector(':scope > .vp-sidebar-header a.vp-sidebar-title');
          if (groupLink && groupLink.getAttribute('href') && !seen.has(groupLink.getAttribute('href'))) {
            seen.add(groupLink.getAttribute('href'));
            pages.push({ 
              title: groupTitle, 
              url: groupLink.getAttribute('href'), 
              folder: topFolder 
            });
          }
          
          // 获取该组下的所有子页面
          var links = subGroup.querySelectorAll('ul.vp-sidebar-links .vp-sidebar-link');
          links.forEach(function(a) {
            var href = a.getAttribute('href');
            var title = a.textContent.trim();
            if (href && !seen.has(href) && href !== '#') {
              seen.add(href);
              pages.push({ 
                title: title, 
                url: href, 
                folder: groupTitle || topFolder 
              });
            }
          });
        });
        
        // 直接二级链接（不带 group 的情况）
        var directLinks = group.querySelectorAll(':scope > ul.vp-sidebar-links > li > a.vp-sidebar-link');
        directLinks.forEach(function(a) {
          var href = a.getAttribute('href');
          var title = a.textContent.trim();
          if (href && !seen.has(href) && href !== '#') {
            seen.add(href);
            pages.push({ 
              title: title, 
              url: href, 
              folder: topFolder 
            });
          }
        });
      });
    } else {
      // 备用方案：直接查找所有侧边栏链接
      var allLinks = document.querySelectorAll('.vp-sidebar-links .vp-sidebar-link, .sidebar-link');
      allLinks.forEach(function(a) {
        var href = a.getAttribute('href');
        var title = a.textContent.trim();
        if (href && !seen.has(href) && href !== '#' && !href.startsWith('http')) {
          seen.add(href);
          pages.push({ title: title, url: href, folder: '' });
        }
      });
    }

    log('VuePress 提取到 ' + pages.length + ' 个页面');
    return pages;
  }

  // ==================== URL 处理 ====================
  function getBaseUrl() {
    return location.origin;
  }

  function getSiteName() {
    var title = document.querySelector('title');
    if (!title) return location.hostname.replace('www.', '').split('.')[0];

    // 处理 VuePress 标题格式： "页面标题 | 站点名称"
    var parts = title.textContent.split(/\s*\|\s*/);
    var name = parts.length > 1 ? parts[parts.length - 1] : parts[0];
    name = name.split(/\s+[-–—]\s+/).pop();
    return name.trim();
  }

  // 获取 .md 文件 URL
  function getMdUrl(pageUrl) {
    // 移除 .html 后缀，添加 .md
    var path = pageUrl.replace(/\.html$/, '');
    if (path.endsWith('/')) path += 'index';
    return BASE_URL + (path.startsWith('/') ? '' : '/') + path + '.md';
  }

  function sanitizeFileName(name) {
    return name
      .replace(/[<>:"/\\|?*]/g, '-')
      .replace(/[\x00-\x1f]/g, '')
      .replace(/\s+/g, ' ')
      .trim()
      .substring(0, 200);
  }

  // ==================== 带重试的 fetch ====================
  async function fetchWithRetry(url, retries) {
    var lastError;

    for (var i = 0; i <= (retries || CONFIG.MAX_RETRY); i++) {
      try {
        var data = await fetchMarkdown(url);
        return data;
      } catch (e) {
        lastError = e;
        log(`重试 ${i + 1}/${CONFIG.MAX_RETRY}: ${url}`, e.message);
        if (i < CONFIG.MAX_RETRY) await delay(CONFIG.RETRY_DELAY);
      }
    }

    throw lastError;
  }

  // ==================== iframe 加载 .md 文件 ====================
  function fetchMarkdown(url) {
    return new Promise(function(resolve, reject) {
      var iframe = document.createElement('iframe');
      var timer;
      var isDone = false;

      iframe.style.cssText = 'position:fixed;top:-9999px;left:-9999px;width:1px;height:1px;border:none;';
      iframe.src = url;

      function cleanup() {
        if (timer) clearTimeout(timer);
        if (iframe.parentNode) iframe.parentNode.removeChild(iframe);
      }

      timer = setTimeout(function() {
        if (!isDone) {
          isDone = true;
          cleanup();
          reject(new Error('请求超时: ' + url));
        }
      }, CONFIG.TIMEOUT);

      iframe.onload = function() {
        if (isDone) return;
        isDone = true;
        clearTimeout(timer);

        try {
          var doc = iframe.contentDocument || iframe.contentWindow.document;
          var body = doc.body;

          if (!body) {
            cleanup();
            reject(new Error('无法读取文档内容: ' + url));
            return;
          }

          var pre = body.querySelector('pre');
          var rawText = pre ? pre.textContent : (body.textContent || body.innerText);

          if (!rawText || rawText.trim() === '') {
            cleanup();
            reject(new Error('文档内容为空: ' + url));
            return;
          }

          var title = extractTitle(rawText);
          cleanup();
          resolve({ title: title, md: rawText.trim() });
        } catch (e) {
          cleanup();
          reject(new Error('解析失败: ' + e.message));
        }
      };

      iframe.onerror = function() {
        if (!isDone) {
          isDone = true;
          cleanup();
          reject(new Error('网络错误: ' + url));
        }
      };

      document.body.appendChild(iframe);
    });
  }

  function extractTitle(mdContent) {
    // 方法1: 匹配第一个 # 标题
    var h1Match = mdContent.match(/^#\s+(.+)$/m);
    if (h1Match) return h1Match[1].trim();

    // 方法2: 提取 frontmatter 中的 title
    if (mdContent.startsWith('---')) {
      var end = mdContent.indexOf('---', 3);
      if (end > -1) {
        var fm = mdContent.substring(3, end);
        var fmMatch = fm.match(/^title:\s*(.+)$/m);
        if (fmMatch) return fmMatch[1].trim();
      }
    }

    return '';
  }

  // ==================== 下载文件到文件夹 ====================
  function downloadToFolder(content, filename, folderName) {
    return new Promise(function(resolve, reject) {
      var fullPath = folderName + '/' + filename;
      var blob = new Blob([content], { type: 'text/markdown;charset=utf-8' });
      var url = URL.createObjectURL(blob);
      
      GM_download({
        url: url,
        name: fullPath,
        saveAs: false,
        onload: function() {
          URL.revokeObjectURL(url);
          log('✅ 已保存: ' + fullPath);
          resolve();
        },
        onerror: function(error) {
          URL.revokeObjectURL(url);
          log('❌ 保存失败: ' + fullPath, error);
          reject(error);
        }
      });
    });
  }

  // ==================== 创建文件夹 ====================
  async function ensureFolder(folderName) {
    if (CURRENT_FOLDER === folderName) return true;
    
    var keepContent = '# This folder is created by Document Downloader\n';
    
    return new Promise(function(resolve) {
      var blob = new Blob([keepContent], { type: 'text/plain;charset=utf-8' });
      var url = URL.createObjectURL(blob);
      
      GM_download({
        url: url,
        name: folderName + '/.keep',
        saveAs: false,
        onload: function() {
          URL.revokeObjectURL(url);
          CURRENT_FOLDER = folderName;
          log('📁 文件夹已创建: ' + folderName);
          resolve(true);
        },
        onerror: function(error) {
          URL.revokeObjectURL(url);
          log('⚠️ 创建文件夹失败，将保存到默认位置', error);
          resolve(false);
        }
      });
    });
  }

  // ==================== UI 创建 ====================
  function createUI(pages, siteName) {
    if (document.getElementById('doc-dl-btn')) return;

    var btn = document.createElement('button');
    btn.id = 'doc-dl-btn';
    btn.innerHTML = '📥<br><span style="font-size:10px;font-weight:400;">' + pages.length + '篇</span>';
    btn.title = '下载 ' + siteName + ' 文档 (.md 源码)';
    btn.style.cssText = 'position:fixed;bottom:24px;right:24px;z-index:2147483646;padding:10px 16px;background:#6366f1;color:#fff;border:none;border-radius:12px;font-size:14px;font-weight:600;cursor:pointer;box-shadow:0 4px 20px rgba(99,102,241,.45);font-family:-apple-system,BlinkMacSystemFont,sans-serif;transition:all .2s;line-height:1.3';
    btn.onmouseenter = function() { btn.style.transform = 'scale(1.05)'; };
    btn.onmouseleave = function() { btn.style.transform = 'scale(1)'; };

    var statusDiv = document.createElement('div');
    statusDiv.id = 'doc-dl-status';
    statusDiv.style.cssText = 'position:fixed;bottom:100px;right:24px;z-index:2147483646;background:#fff;border-radius:10px;padding:14px 18px;box-shadow:0 4px 24px rgba(0,0,0,.15);font-size:13px;font-family:-apple-system,BlinkMacSystemFont,sans-serif;min-width:240px;display:none;line-height:1.6;color:#333';
    document.body.appendChild(statusDiv);

    btn.onclick = function() { startDownload(pages, siteName, btn, statusDiv); };
    document.body.appendChild(btn);

    log('UI 就绪 — ' + siteName + ' (' + SITE_TYPE + ') — ' + pages.length + ' 篇');
  }

  // ==================== 下载流程 ====================
  async function startDownload(pages, siteName, btn, statusDiv) {
    if (btn._running) return;

    btn._running = true;
    btn.style.opacity = '0.6';
    btn.style.pointerEvents = 'none';
    statusDiv.style.display = 'block';

    var total = pages.length;
    var ok = 0, fail = 0;
    var startTime = Date.now();
    BASE_URL = getBaseUrl();
    
    var folderName = siteName + '_docs';
    await ensureFolder(folderName);
    
    var usedNames = {};

    for (var i = 0; i < total; i++) {
      var page = pages[i];
      var url = getMdUrl(page.url);

      updateStatus(statusDiv, i, total, page.title, ok, fail);

      try {
        var data = await fetchWithRetry(url, CONFIG.MAX_RETRY);
        var title = data.title || page.title || 'untitled';
        var safeName = sanitizeFileName(title);
        var folder = page.folder ? sanitizeFileName(page.folder) + '/' : '';
        
        var fname = folder + safeName + '.md';
        if (usedNames[fname] !== undefined) {
          usedNames[fname]++;
          fname = folder + safeName + ' (' + usedNames[fname] + ').md';
        } else {
          usedNames[fname] = 0;
        }

        await downloadToFolder(data.md, fname, folderName);
        ok++;
      } catch (e) {
        fail++;
        log('❌ 失败: ' + (page.title || url), e.message);
      }

      if (i < total - 1) await delay(CONFIG.DELAY);
    }

    var elapsed = ((Date.now() - startTime) / 1000).toFixed(1);
    statusDiv.innerHTML = [
      '<strong style="color:#22c55e;">✅ 完成!</strong>',
      '<div>成功 ' + ok + ' / 失败 ' + fail + ' / ' + total + '</div>',
      '<div style="font-size:11px;color:#888;">📁 保存到: ' + folderName + '/</div>',
      '<div style="font-size:11px;color:#888;">⏱ ' + elapsed + 's · .md 源码</div>'
    ].join('');
    
    log('✅ 下载完成, 成功: ' + ok + ', 失败: ' + fail);

    setTimeout(function() { statusDiv.style.display = 'none'; }, 10000);

    btn._running = false;
    btn.style.opacity = '1';
    btn.style.pointerEvents = 'auto';
  }

  function updateStatus(statusDiv, index, total, title, ok, fail) {
    var percent = ((index / total) * 100);
    var shortTitle = (title || '').substring(0, 40);

    statusDiv.innerHTML = [
      '<strong>📥 ' + (index + 1) + '/' + total + '</strong>',
      '<span style="font-size:11px;color:#666;margin-left:6px;">' + shortTitle + '</span>',
      '<div style="height:4px;background:#eee;border-radius:2px;margin-top:6px;">',
        '<div style="height:100%;background:#6366f1;border-radius:2px;width:' + percent + '%;"></div>',
      '</div>',
      '<div style="font-size:11px;color:#888;margin-top:4px;">✅ ' + ok + ' &nbsp; ❌ ' + fail + '</div>'
    ].join('');
  }

  // ==================== SPA 导航监听 ====================
  function initNavigationWatch() {
    var lastPath = location.pathname;

    function checkNav() {
      if (location.pathname !== lastPath) {
        lastPath = location.pathname;
        setTimeout(function() {
          var newType = detectSiteType();
          if (newType && !document.getElementById('doc-dl-btn')) {
            SITE_TYPE = newType;
            var pages = extractPages();
            if (pages.length) {
              var siteName = getSiteName();
              createUI(pages, siteName);
            }
          }
        }, 1000);
      }
    }

    var observer = new MutationObserver(checkNav);
    observer.observe(document.body, { childList: true, subtree: true });
    window.addEventListener('popstate', function() { setTimeout(checkNav, 500); });
  }

  // ==================== 初始化 ====================
  async function init() {
    SITE_TYPE = detectSiteType();
    
    if (!SITE_TYPE) {
      log('未检测到 VitePress 或 VuePress 站点，跳过');
      return;
    }

    log('检测到站点类型: ' + SITE_TYPE);

    var siteName = getSiteName();
    var pages = extractPages();

    if (!pages.length) {
      setTimeout(function() {
        var retryPages = extractPages();
        if (retryPages.length) createUI(retryPages, siteName);
      }, 2000);
      return;
    }

    createUI(pages, siteName);
    initNavigationWatch();
  }

  // ==================== 启动 ====================
  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', function() { setTimeout(init, 500); });
  } else {
    setTimeout(init, 500);
  }
})();