let currentCategory = '';
let currentDoc = '';
let docList = [];
let currentMarkdownContent = ''; // 保存当前文档的markdown源码
let isEditMode = false; // 是否处于编辑模式
let savedScrollPosition = 0; // 保存的滚动位置

// DOM 元素缓存
const DOM = {
    loading: null,
    content: null,
    docNav: null,
    toc: null,
    leftSidebar: null,
    rightSidebar: null,
    editBtn: null,
    editorContainer: null,
    markdownEditor: null,
    editorDocName: null
};

// 配置 marked
marked.setOptions({
    highlight: function(code, lang) {
        if (lang && hljs.getLanguage(lang)) {
            try {
                return hljs.highlight(code, { language: lang }).value;
            } catch (err) {
                console.error('Highlight error:', err);
            }
        }
        return hljs.highlightAuto(code).value;
    },
    breaks: true,
    gfm: true
});

// 从 URL 获取参数
function getQueryParams() {
    const params = new URLSearchParams(window.location.search);
    return {
        category: params.get('category'),
        doc: params.get('doc')
    };
}

// 加载文档列表
async function loadDocList() {
    const { category } = getQueryParams();
    if (!category) {
        window.location.href = '/';
        return;
    }

    currentCategory = category;
    const categoryNameSpan = document.querySelector('#category-title .category-name');
    if (categoryNameSpan) {
        categoryNameSpan.textContent = category;
    }

    try {
        const response = await fetch(`/api/category/${encodeURIComponent(category)}`);
        if (!response.ok) throw new Error('获取文档列表失败');

        const categoryData = await response.json();
        docList = categoryData.docs;

        renderDocNav(docList);

        // 加载第一篇文档（或 URL 指定的文档）
        const { doc } = getQueryParams();
        const firstDoc = doc || docList[0]?.name;

        if (firstDoc) {
            loadDocument(firstDoc);
        }

    } catch (err) {
        console.error('Error loading doc list:', err);
        showError('加载文档列表失败');
    }
}

// 渲染文档导航
function renderDocNav(docs) {
    const nav = DOM.docNav || document.getElementById('doc-nav');
    if (!DOM.docNav) DOM.docNav = nav;

    nav.innerHTML = '';

    docs.forEach(doc => {
        const item = document.createElement('div');
        item.className = `nav-item level-${doc.level}`;
        item.dataset.docName = doc.name;

        const link = document.createElement('a');
        link.href = '#';
        link.className = 'nav-link';
        link.textContent = doc.name;

        item.appendChild(link);
        nav.appendChild(item);
    });

    // 使用事件委托 - 只添加一个监听器
    nav.removeEventListener('click', handleNavClick);
    nav.addEventListener('click', handleNavClick);
}

// 导航点击处理函数
function handleNavClick(e) {
    if (e.target.classList.contains('nav-link')) {
        e.preventDefault();
        const item = e.target.parentElement;
        const docName = item.dataset.docName;

        if (docName) {
            loadDocument(docName);
            updateURL(currentCategory, docName);

            // 更新活动状态 - 使用缓存的查询结果
            const navItems = DOM.docNav.querySelectorAll('.nav-item');
            navItems.forEach(el => el.classList.toggle('active', el === item));
        }
    }
}

// 加载文档内容
async function loadDocument(docName, scrollToText = null) {
    // 使用 DOM 缓存
    if (!DOM.loading) DOM.loading = document.getElementById('loading');
    if (!DOM.content) DOM.content = document.getElementById('markdown-content');

    DOM.loading.style.display = 'flex';
    DOM.content.innerHTML = '';

    try {
        const response = await fetch(`/api/doc/${encodeURIComponent(currentCategory)}/${encodeURIComponent(docName)}`);

        if (!response.ok) {
            const errorData = await response.json().catch(() => ({}));
            throw new Error(errorData.error || `加载失败 (${response.status})`);
        }

        const data = await response.json();

        // 验证数据有效性
        if (!data.content || typeof data.content !== 'string') {
            throw new Error('文档内容格式错误');
        }

        currentDoc = docName;
        currentMarkdownContent = data.content; // 保存markdown源码

        // 渲染 Markdown
        const html = marked.parse(data.content);
        DOM.content.innerHTML = html;

        // 生成 TOC
        generateTOC();

        // 更新活动文档 - 使用 toggle 优化
        if (DOM.docNav) {
            const navItems = DOM.docNav.querySelectorAll('.nav-item');
            navItems.forEach(el => el.classList.toggle('active', el.dataset.docName === docName));
        }

        DOM.loading.style.display = 'none';

        // 如果指定了要滚动到的文本，等待渲染完成后滚动
        if (scrollToText) {
            setTimeout(() => {
                scrollToSearchMatch(scrollToText);
            }, 100);
        }

    } catch (err) {
        console.error('Error loading document:', err);
        DOM.loading.style.display = 'none';
        showError(`加载文档失败：${err.message || '请稍后重试'}`);
    }
}

// 生成 TOC
function generateTOC() {
    // 使用 DOM 缓存
    if (!DOM.toc) DOM.toc = document.getElementById('toc');

    const headings = DOM.content.querySelectorAll('h1, h2, h3, h4, h5, h6');
    DOM.toc.innerHTML = '';

    if (headings.length === 0) {
        DOM.toc.innerHTML = '<p class="toc-empty">本文档没有标题</p>';
        return;
    }

    // 创建标题 ID 映射
    const headingMap = new Map();

    headings.forEach((heading, index) => {
        // 给标题添加 ID
        if (!heading.id) {
            heading.id = `heading-${index}`;
        }

        const level = parseInt(heading.tagName.substring(1));
        const link = document.createElement('a');
        link.href = `#${heading.id}`;
        link.className = `toc-link toc-level-${level}`;
        link.textContent = heading.textContent;

        headingMap.set(heading.id, heading);
        DOM.toc.appendChild(link);
    });

    // 使用事件委托 - 只添加一个监听器
    DOM.toc.removeEventListener('click', handleTocClick);
    DOM.toc.addEventListener('click', (e) => handleTocClick(e, headingMap));

    // 监听滚动，高亮当前标题
    setupScrollSpy(headings);
}

// TOC 点击处理函数
function handleTocClick(e, headingMap) {
    if (e.target.classList.contains('toc-link')) {
        e.preventDefault();
        const headingId = e.target.getAttribute('href').substring(1);
        const heading = headingMap.get(headingId);

        if (heading) {
            heading.scrollIntoView({ behavior: 'smooth', block: 'start' });

            // 更新活动状态
            const tocLinks = DOM.toc.querySelectorAll('.toc-link');
            tocLinks.forEach(el => el.classList.toggle('active', el === e.target));
        }
    }
}

// 滚动监听
function setupScrollSpy(headings) {
    let activeLink = null;

    const observer = new IntersectionObserver((entries) => {
        entries.forEach(entry => {
            if (entry.isIntersecting) {
                const id = entry.target.id;
                const link = DOM.toc.querySelector(`.toc-link[href="#${id}"]`);

                if (link && link !== activeLink) {
                    // 只在需要时更新，减少 DOM 操作
                    if (activeLink) activeLink.classList.remove('active');
                    link.classList.add('active');
                    activeLink = link;
                }
            }
        });
    }, {
        rootMargin: '-100px 0px -80% 0px',
        threshold: 0
    });

    headings.forEach(heading => observer.observe(heading));
}

// 更新 URL
function updateURL(category, doc) {
    const url = new URL(window.location);
    url.searchParams.set('category', category);
    url.searchParams.set('doc', doc);
    window.history.pushState({}, '', url);
}

// 显示错误
function showError(message) {
    const content = document.getElementById('markdown-content');
    content.innerHTML = `<div class="error-message">${message}</div>`;
}

// 切换侧边栏（移动端）
function setupSidebarToggles() {
    const toggleLeft = document.getElementById('toggle-left');
    const toggleRight = document.getElementById('toggle-right');

    // 使用 DOM 缓存
    if (!DOM.leftSidebar) DOM.leftSidebar = document.getElementById('left-sidebar');
    if (!DOM.rightSidebar) DOM.rightSidebar = document.getElementById('right-sidebar');

    // 移动端/平板初始化：默认折叠侧边栏
    if (window.innerWidth <= 768) {
        DOM.leftSidebar.classList.add('collapsed');
        DOM.rightSidebar.classList.add('collapsed');
    } else if (window.innerWidth <= 1024) {
        // 平板：只折叠右侧栏
        DOM.rightSidebar.classList.add('collapsed');
    }

    // 监听窗口大小变化
    window.addEventListener('resize', () => {
        if (window.innerWidth <= 768) {
            // 移动端：确保左右侧边栏都折叠
            if (!DOM.leftSidebar.classList.contains('collapsed')) {
                DOM.leftSidebar.classList.add('collapsed');
            }
            if (!DOM.rightSidebar.classList.contains('collapsed')) {
                DOM.rightSidebar.classList.add('collapsed');
            }
        } else if (window.innerWidth <= 1024) {
            // 平板：只折叠右侧栏，展开左侧栏
            DOM.leftSidebar.classList.remove('collapsed');
            if (!DOM.rightSidebar.classList.contains('collapsed')) {
                DOM.rightSidebar.classList.add('collapsed');
            }
        } else {
            // 桌面端：展开所有侧边栏
            DOM.leftSidebar.classList.remove('collapsed');
            DOM.rightSidebar.classList.remove('collapsed');
        }
    });

    toggleLeft.onclick = (e) => {
        e.stopPropagation();

        // 如果右侧栏展开，先隐藏它
        if (!DOM.rightSidebar.classList.contains('collapsed')) {
            DOM.rightSidebar.classList.add('collapsed');
        }

        DOM.leftSidebar.classList.toggle('collapsed');
    };

    toggleRight.onclick = (e) => {
        e.stopPropagation();

        // 如果左侧栏展开，先隐藏它
        if (!DOM.leftSidebar.classList.contains('collapsed')) {
            DOM.leftSidebar.classList.add('collapsed');
        }

        DOM.rightSidebar.classList.toggle('collapsed');
    };

    // 点击侧边栏外部时隐藏所有已展开的侧边栏（仅在移动端和平板）
    document.addEventListener('click', (e) => {
        // 仅在移动端和平板上启用此功能
        if (window.innerWidth > 1024) return;

        const isClickInsideLeftSidebar = DOM.leftSidebar.contains(e.target);
        const isClickInsideRightSidebar = DOM.rightSidebar.contains(e.target);
        const isToggleButton = e.target.closest('#toggle-left') || e.target.closest('#toggle-right');

        // 如果点击的不是侧边栏内部，也不是切换按钮，则隐藏所有展开的侧边栏
        if (!isClickInsideLeftSidebar && !isClickInsideRightSidebar && !isToggleButton) {
            if (!DOM.leftSidebar.classList.contains('collapsed')) {
                DOM.leftSidebar.classList.add('collapsed');
            }
            if (!DOM.rightSidebar.classList.contains('collapsed')) {
                DOM.rightSidebar.classList.add('collapsed');
            }
        }
    });
}

// 搜索功能
function initSearch() {
    const searchContainer = document.getElementById('search-container');
    const searchToggleBtn = document.getElementById('search-toggle-btn');
    const searchInput = document.getElementById('search-input');
    const searchBtn = document.getElementById('search-btn');
    const searchResults = document.getElementById('search-results');
    const closeSearchBoxBtn = document.getElementById('close-search-box');

    // 检查元素是否存在
    if (!searchContainer || !searchToggleBtn || !searchInput || !searchBtn || !searchResults || !closeSearchBoxBtn) {
        console.error('Search elements not found:', {
            searchContainer: !!searchContainer,
            searchToggleBtn: !!searchToggleBtn,
            searchInput: !!searchInput,
            searchBtn: !!searchBtn,
            searchResults: !!searchResults,
            closeSearchBoxBtn: !!closeSearchBoxBtn
        });
        return;
    }

    let searchTimeout;
    const SEARCH_HISTORY_KEY = 'cjydocs_search_history';

    // 保存搜索历史到localStorage
    const saveSearchHistory = (query) => {
        if (!query || query.trim().length < 2) return;

        try {
            let history = JSON.parse(localStorage.getItem(SEARCH_HISTORY_KEY) || '{}');
            history[currentCategory] = query;
            localStorage.setItem(SEARCH_HISTORY_KEY, JSON.stringify(history));
        } catch (err) {
            console.error('Failed to save search history:', err);
        }
    };

    // 搜索函数
    const performSearch = async () => {
        const query = searchInput.value.trim();

        if (query.length < 2) {
            searchResults.style.display = 'none';
            return;
        }

        // 保存搜索历史
        saveSearchHistory(query);

        try {
            const response = await fetch(
                `/api/search/${encodeURIComponent(currentCategory)}?q=${encodeURIComponent(query)}&currentDoc=${encodeURIComponent(currentDoc)}`
            );

            if (!response.ok) {
                const errorData = await response.json().catch(() => ({}));
                throw new Error(errorData.error || `搜索失败 (${response.status})`);
            }

            const data = await response.json();
            displaySearchResults(data);
            searchResults.style.display = 'block';

        } catch (err) {
            console.error('Search error:', err);
            // 向用户显示错误信息
            displaySearchError(err.message || '搜索失败，请稍后重试');
        }
    };

    // 加载搜索历史
    const loadSearchHistory = () => {
        try {
            const history = JSON.parse(localStorage.getItem(SEARCH_HISTORY_KEY) || '{}');
            const lastQuery = history[currentCategory];

            if (lastQuery) {
                searchInput.value = lastQuery;
                // 自动搜索上次的内容
                performSearch();
            }
        } catch (err) {
            console.error('Failed to load search history:', err);
        }
    };

    // 清除其他分类的搜索历史
    const clearOtherCategoryHistory = () => {
        try {
            let history = JSON.parse(localStorage.getItem(SEARCH_HISTORY_KEY) || '{}');
            // 只保留当前分类
            history = { [currentCategory]: history[currentCategory] || '' };
            localStorage.setItem(SEARCH_HISTORY_KEY, JSON.stringify(history));
        } catch (err) {
            console.error('Failed to clear search history:', err);
        }
    };

    // 切换搜索框显示/隐藏
    searchToggleBtn.addEventListener('click', (e) => {
        e.stopPropagation();
        console.log('Search button clicked');
        const isActive = searchContainer.classList.toggle('active');
        console.log('Search container active:', isActive);

        if (isActive) {
            // 加载搜索历史
            loadSearchHistory();
            // 聚焦到搜索框
            setTimeout(() => searchInput.focus(), 100);
        } else {
            // 隐藏搜索结果
            searchResults.style.display = 'none';
        }
    });

    // 输入时实时搜索（防抖） - 500ms 减少 API 调用
    searchInput.addEventListener('input', () => {
        clearTimeout(searchTimeout);
        searchTimeout = setTimeout(performSearch, 500);
    });

    // 点击搜索按钮
    searchBtn.addEventListener('click', performSearch);

    // 按回车搜索
    searchInput.addEventListener('keypress', (e) => {
        if (e.key === 'Enter') {
            performSearch();
        }
    });

    // 关闭搜索框按钮
    closeSearchBoxBtn.addEventListener('click', (e) => {
        e.stopPropagation();
        searchContainer.classList.remove('active');
        searchResults.style.display = 'none';
    });

    // 点击搜索结果外部关闭
    searchResults.addEventListener('click', (e) => {
        // 如果点击的是搜索结果容器本身（即遮罩背景），关闭搜索
        if (e.target === searchResults) {
            searchResults.style.display = 'none';
        }
    });

    // 点击外部关闭
    document.addEventListener('click', (e) => {
        const searchToggle = document.getElementById('search-toggle-btn');

        if (!searchResults.contains(e.target) &&
            !searchInput.contains(e.target) &&
            !searchBtn.contains(e.target) &&
            !searchContainer.contains(e.target) &&
            !searchToggle.contains(e.target)) {
            searchResults.style.display = 'none';
        }
    });

    // 初始化时清除其他分类的历史
    clearOtherCategoryHistory();
}

// 显示搜索错误
function displaySearchError(message) {
    const currentDocSection = document.querySelector('#current-doc-results .results-list');
    const otherDocsSection = document.querySelector('#other-docs-results .results-list');
    const searchResults = document.getElementById('search-results');

    // 清空之前的结果
    currentDocSection.innerHTML = '';
    otherDocsSection.innerHTML = '';

    // 隐藏分组标题
    document.getElementById('current-doc-results').style.display = 'none';
    document.getElementById('other-docs-results').style.display = 'none';

    // 显示错误信息
    currentDocSection.innerHTML = `<p class="search-error" style="color: #d73a49; padding: 20px; text-align: center;">${message}</p>`;
    document.getElementById('current-doc-results').style.display = 'block';

    // 显示搜索结果面板
    searchResults.style.display = 'block';
}

// 显示搜索结果
function displaySearchResults(data) {
    const currentDocSection = document.querySelector('#current-doc-results .results-list');
    const otherDocsSection = document.querySelector('#other-docs-results .results-list');

    // 清空之前的结果
    currentDocSection.innerHTML = '';
    otherDocsSection.innerHTML = '';

    // 隐藏/显示分组标题
    document.getElementById('current-doc-results').style.display =
        data.currentDoc.length > 0 ? 'block' : 'none';
    document.getElementById('other-docs-results').style.display =
        data.otherDocs.length > 0 ? 'block' : 'none';

    // 渲染当前文档结果
    if (data.currentDoc.length > 0) {
        data.currentDoc.forEach(doc => {
            const docResults = createDocResultElement(doc, true);
            currentDocSection.appendChild(docResults);
        });
    } else {
        currentDocSection.innerHTML = '<p class="no-results">当前文档无匹配结果</p>';
    }

    // 渲染其他文档结果
    if (data.otherDocs.length > 0) {
        data.otherDocs.forEach(doc => {
            const docResults = createDocResultElement(doc, false);
            otherDocsSection.appendChild(docResults);
        });
    } else if (data.currentDoc.length === 0) {
        otherDocsSection.innerHTML = '<p class="no-results">未找到匹配结果</p>';
    }
}

// 创建搜索结果元素
function createDocResultElement(doc, isCurrent) {
    const container = document.createElement('div');
    container.className = 'search-result-item';

    const header = document.createElement('div');
    header.className = 'result-header';
    header.innerHTML = `
        <span class="result-doc-name">${doc.docName}</span>
        <span class="result-count">${doc.matchCount} 个匹配</span>
    `;
    container.appendChild(header);

    // 添加匹配片段
    doc.matches.forEach(match => {
        const matchItem = document.createElement('div');
        matchItem.className = 'result-match';

        // 高亮搜索词
        const highlightedSnippet = highlightSearchTerm(match.snippet, document.getElementById('search-input').value);

        matchItem.innerHTML = `
            <div class="match-line-number">行 ${match.line}</div>
            <div class="match-snippet">${highlightedSnippet}</div>
        `;

        // 点击跳转
        matchItem.onclick = () => {
            // 隐藏搜索框和搜索结果
            const searchContainer = document.querySelector('.search-container');
            const searchResults = document.getElementById('search-results');
            searchContainer.classList.remove('active');
            searchResults.style.display = 'none';

            // 在移动端和平板上关闭所有侧边栏，确保用户能看到跳转后的内容
            if (window.innerWidth <= 1024) {
                if (DOM.leftSidebar && !DOM.leftSidebar.classList.contains('collapsed')) {
                    DOM.leftSidebar.classList.add('collapsed');
                }
                if (DOM.rightSidebar && !DOM.rightSidebar.classList.contains('collapsed')) {
                    DOM.rightSidebar.classList.add('collapsed');
                }
            }

            if (isCurrent) {
                // 当前文档，滚动到对应位置
                scrollToSearchMatch(match.fullLine);
            } else {
                // 其他文档，加载该文档并跳转到具体位置
                loadDocument(doc.docName, match.fullLine);
            }
        };

        container.appendChild(matchItem);
    });

    return container;
}

// 高亮搜索词
function highlightSearchTerm(text, searchTerm) {
    const regex = new RegExp(`(${searchTerm})`, 'gi');
    return text.replace(regex, '<mark class="search-highlight">$1</mark>');
}

// 滚动到搜索匹配位置
function scrollToSearchMatch(fullLine) {
    const content = document.getElementById('markdown-content');
    const searchText = fullLine.trim();

    if (!searchText) return;

    // 使用TreeWalker遍历所有文本节点
    const walker = document.createTreeWalker(
        content,
        NodeFilter.SHOW_TEXT,
        null
    );

    let found = false;
    let node;

    while (node = walker.nextNode()) {
        if (node.textContent.includes(searchText)) {
            const parentElement = node.parentElement;

            // 滚动到元素
            parentElement.scrollIntoView({ behavior: 'smooth', block: 'center' });

            // 临时高亮父元素
            parentElement.classList.add('temp-highlight');
            setTimeout(() => {
                parentElement.classList.remove('temp-highlight');
            }, 2000);

            found = true;
            break;
        }
    }

    // 如果没有找到精确匹配，尝试部分匹配
    if (!found) {
        const elements = content.querySelectorAll('p, li, td, th, h1, h2, h3, h4, h5, h6, blockquote, pre, code');

        for (const element of elements) {
            const text = element.textContent.trim();
            // 尝试匹配至少50%的内容
            if (text.length > 10 && searchText.includes(text.substring(0, Math.min(text.length, 50)))) {
                element.scrollIntoView({ behavior: 'smooth', block: 'center' });

                // 临时高亮
                element.classList.add('temp-highlight');
                setTimeout(() => {
                    element.classList.remove('temp-highlight');
                }, 2000);

                break;
            }
        }
    }
}

// 设置回到顶部按钮
function setupBackToTop() {
    const backToTopBtn = document.getElementById('back-to-top');
    const contentArea = document.getElementById('content-area');

    if (!backToTopBtn || !contentArea) return;

    // 初始状态：隐藏按钮
    backToTopBtn.classList.add('hidden');

    // 点击按钮滚动到顶部
    backToTopBtn.addEventListener('click', () => {
        contentArea.scrollTo({
            top: 0,
            behavior: 'smooth'
        });
    });

    // 监听滚动事件，控制按钮显示/隐藏
    let scrollTimeout;
    contentArea.addEventListener('scroll', () => {
        clearTimeout(scrollTimeout);
        scrollTimeout = setTimeout(() => {
            if (contentArea.scrollTop > 300) {
                backToTopBtn.classList.remove('hidden');
            } else {
                backToTopBtn.classList.add('hidden');
            }
        }, 100);
    });
}

// 编辑功能
function setupEditFeature() {
    // 缓存DOM元素
    if (!DOM.editBtn) DOM.editBtn = document.getElementById('edit-btn');
    if (!DOM.editorContainer) DOM.editorContainer = document.getElementById('editor-container');
    if (!DOM.markdownEditor) DOM.markdownEditor = document.getElementById('markdown-editor');
    if (!DOM.editorDocName) DOM.editorDocName = document.getElementById('editor-doc-name');

    const saveBtn = document.getElementById('save-btn');
    const cancelBtn = document.getElementById('cancel-edit-btn');
    const contentArea = document.getElementById('content-area');

    // 编辑按钮点击事件 - 切换编辑/查看模式
    DOM.editBtn.addEventListener('click', () => {
        if (isEditMode) {
            exitEditMode();
        } else {
            enterEditMode();
        }
    });

    // 取消编辑
    cancelBtn.addEventListener('click', () => {
        exitEditMode();
    });

    // 保存按钮
    saveBtn.addEventListener('click', async () => {
        await saveDocument();
    });
}

// 进入编辑模式
function enterEditMode() {
    if (!currentDoc || !currentMarkdownContent) {
        alert('请先加载一个文档');
        return;
    }

    isEditMode = true;

    // 更新编辑按钮状态
    DOM.editBtn.classList.add('active');
    DOM.editBtn.title = '退出编辑';

    // 保存当前滚动位置
    const contentArea = document.getElementById('content-area');
    savedScrollPosition = contentArea.scrollTop;

    // 找到当前视口中心附近的元素
    const visibleElement = findVisibleElement();

    // 隐藏渲染的内容
    if (!DOM.content) DOM.content = document.getElementById('markdown-content');
    DOM.content.style.display = 'none';

    // 显示编辑器
    DOM.editorContainer.style.display = 'flex';
    DOM.editorDocName.textContent = `${currentDoc}.md`;
    DOM.markdownEditor.value = currentMarkdownContent;

    // 定位光标到对应位置
    setTimeout(() => {
        if (visibleElement) {
            positionCursorByElement(visibleElement);
        } else {
            // 如果找不到元素，使用滚动比例
            const scrollRatio = savedScrollPosition / contentArea.scrollHeight;
            DOM.markdownEditor.scrollTop = DOM.markdownEditor.scrollHeight * scrollRatio;
        }
        DOM.markdownEditor.focus();
    }, 50);
}

// 找到当前视口中可见的元素
function findVisibleElement() {
    const contentArea = document.getElementById('content-area');
    const viewportTop = contentArea.scrollTop;
    const viewportMiddle = viewportTop + contentArea.clientHeight / 3; // 视口上方1/3处

    // 查找所有重要元素（标题、段落等）
    const elements = DOM.content.querySelectorAll('h1, h2, h3, h4, h5, h6, p, li, blockquote, pre');

    let closestElement = null;
    let minDistance = Infinity;

    elements.forEach(el => {
        const rect = el.getBoundingClientRect();
        const elementTop = el.offsetTop;
        const distance = Math.abs(elementTop - viewportMiddle);

        if (distance < minDistance && elementTop <= viewportMiddle + 200) {
            minDistance = distance;
            closestElement = el;
        }
    });

    return closestElement;
}

// 根据元素定位光标
function positionCursorByElement(element) {
    const elementText = element.textContent.trim();

    if (!elementText) {
        return;
    }

    // 获取元素标签类型
    const tagName = element.tagName.toLowerCase();
    let searchText = elementText;

    // 如果是标题，添加markdown标记进行搜索
    if (tagName.match(/^h[1-6]$/)) {
        const level = parseInt(tagName[1]);
        const hashes = '#'.repeat(level);

        // 尝试匹配标题行
        const lines = currentMarkdownContent.split('\n');
        let targetLine = -1;

        for (let i = 0; i < lines.length; i++) {
            const line = lines[i].trim();
            // 匹配 "# 标题" 格式
            if (line.startsWith(hashes + ' ') && line.substring(level + 1).trim() === elementText) {
                targetLine = i;
                break;
            }
        }

        if (targetLine !== -1) {
            setEditorCursorToLine(targetLine);
            return;
        }
    }

    // 对于其他元素，搜索文本内容
    const lines = currentMarkdownContent.split('\n');
    for (let i = 0; i < lines.length; i++) {
        const line = lines[i].trim();
        // 移除markdown标记进行比较
        const cleanLine = line.replace(/^[#\-*>]+\s*/, '').trim();

        if (cleanLine.includes(elementText.substring(0, Math.min(50, elementText.length)))) {
            setEditorCursorToLine(i);
            return;
        }
    }
}

// 设置编辑器光标到指定行
function setEditorCursorToLine(lineNumber) {
    const lines = currentMarkdownContent.split('\n');

    // 计算目标位置的字符索引
    let charPosition = 0;
    for (let i = 0; i < lineNumber && i < lines.length; i++) {
        charPosition += lines[i].length + 1; // +1 for newline
    }

    // 设置光标位置
    DOM.markdownEditor.setSelectionRange(charPosition, charPosition);

    // 滚动到光标位置
    const linesBeforeCursor = lineNumber;
    const lineHeight = 22; // 大约的行高（px）
    const targetScrollTop = linesBeforeCursor * lineHeight - DOM.markdownEditor.clientHeight / 3;

    DOM.markdownEditor.scrollTop = Math.max(0, targetScrollTop);
}

// 退出编辑模式
function exitEditMode() {
    isEditMode = false;

    // 更新编辑按钮状态
    DOM.editBtn.classList.remove('active');
    DOM.editBtn.title = '编辑文档';

    // 隐藏编辑器
    DOM.editorContainer.style.display = 'none';

    // 显示渲染的内容
    DOM.content.style.display = 'block';

    // 恢复滚动位置
    const contentArea = document.getElementById('content-area');
    setTimeout(() => {
        contentArea.scrollTop = savedScrollPosition;
    }, 0);
}

// 保存文档
async function saveDocument() {
    const newContent = DOM.markdownEditor.value;

    if (!currentCategory || !currentDoc) {
        alert('无法保存：缺少文档信息');
        return;
    }

    // 禁用保存按钮，防止重复点击
    const saveBtn = document.getElementById('save-btn');
    saveBtn.disabled = true;
    saveBtn.textContent = '保存中...';

    try {
        const response = await fetch(`/api/doc/${encodeURIComponent(currentCategory)}/${encodeURIComponent(currentDoc)}`, {
            method: 'PUT',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({
                content: newContent
            })
        });

        if (!response.ok) {
            const errorData = await response.json().catch(() => ({}));
            throw new Error(errorData.error || `保存失败 (${response.status})`);
        }

        const result = await response.json();

        // 更新本地的markdown内容
        currentMarkdownContent = newContent;

        // 重新渲染内容
        const html = marked.parse(newContent);
        DOM.content.innerHTML = html;

        // 重新生成TOC
        generateTOC();

        // 退出编辑模式
        exitEditMode();

        // 显示成功提示
        showSuccessMessage('保存成功！');

    } catch (error) {
        console.error('Save error:', error);
        alert(`保存失败：${error.message || '请稍后重试'}`);
    } finally {
        // 恢复保存按钮
        saveBtn.disabled = false;
        saveBtn.textContent = '保存';
    }
}

// 显示成功提示
function showSuccessMessage(message) {
    const toast = document.createElement('div');
    toast.className = 'success-toast';
    toast.textContent = message;
    toast.style.cssText = `
        position: fixed;
        top: 20px;
        right: 20px;
        background: #28a745;
        color: white;
        padding: 12px 24px;
        border-radius: 6px;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
        z-index: 10000;
        animation: slideInRight 0.3s ease-out;
    `;

    document.body.appendChild(toast);

    setTimeout(() => {
        toast.style.animation = 'slideOutRight 0.3s ease-out';
        setTimeout(() => {
            document.body.removeChild(toast);
        }, 300);
    }, 2000);
}

// 初始化
document.addEventListener('DOMContentLoaded', () => {
    loadDocList();
    setupSidebarToggles();
    initSearch();
    setupBackToTop();
    setupEditFeature();
});

// 处理浏览器后退/前进
window.addEventListener('popstate', () => {
    const { doc } = getQueryParams();
    if (doc) {
        loadDocument(doc);
    }
});