import { useState, useEffect, useRef } from 'react'
import { useParams } from 'react-router-dom'
import { Layout, Menu, Spin, FloatButton, Button, Modal, Input, message, Drawer, Anchor } from 'antd'
import { VerticalAlignTopOutlined, MenuOutlined, MenuFoldOutlined, MenuUnfoldOutlined, FileTextOutlined, FolderOutlined, FilePdfOutlined, LockOutlined } from '@ant-design/icons'
import ReactMarkdown from 'react-markdown'
import remarkGfm from 'remark-gfm'
import rehypeRaw from 'rehype-raw'
import rehypeSlug from 'rehype-slug'
import rehypeHighlight from 'rehype-highlight'
import 'highlight.js/styles/github.css'
import { getPreviewInfo, getPreviewTree, getPreviewFile, verifyAccessPassword, getPreviewDocumentUrl } from '@/api/share'
import VirtualPDFViewer from '@/components/PDFViewer/VirtualPDFViewer'
import './PreviewPage.css'

const { Sider, Content } = Layout

function PreviewPage() {
  const { projectId } = useParams()
  const [projectInfo, setProjectInfo] = useState(null)
  const [fileTree, setFileTree] = useState([])
  const [selectedFile, setSelectedFile] = useState('')
  const [markdownContent, setMarkdownContent] = useState('')
  const [loading, setLoading] = useState(false)
  const [openKeys, setOpenKeys] = useState([])
  const [tocCollapsed, setTocCollapsed] = useState(false)
  const [tocItems, setTocItems] = useState([])
  const [passwordModalVisible, setPasswordModalVisible] = useState(false)
  const [password, setPassword] = useState('')
  const [accessPassword, setAccessPassword] = useState(null) // 已验证的密码
  const [siderCollapsed, setSiderCollapsed] = useState(false)
  const [mobileDrawerVisible, setMobileDrawerVisible] = useState(false)
  const [isMobile, setIsMobile] = useState(false)
  const [pdfViewerVisible, setPdfViewerVisible] = useState(false)
  const [pdfUrl, setPdfUrl] = useState('')
  const [pdfFilename, setPdfFilename] = useState('')
  const [viewMode, setViewMode] = useState('markdown') // 'markdown' or 'pdf'
  const contentRef = useRef(null)

  // 检测是否为移动设备
  useEffect(() => {
    const checkMobile = () => {
      setIsMobile(window.innerWidth < 768)
    }
    checkMobile()
    window.addEventListener('resize', checkMobile)
    return () => window.removeEventListener('resize', checkMobile)
  }, [])

  useEffect(() => {
    loadProjectInfo()
  }, [projectId])

  // 加载项目基本信息
  const loadProjectInfo = async () => {
    try {
      const res = await getPreviewInfo(projectId)
      const info = res.data
      setProjectInfo(info)

      if (info.has_password) {
        // 需要密码验证
        setPasswordModalVisible(true)
      } else {
        // 无需密码，直接加载文档树
        loadFileTree()
      }
    } catch (error) {
      console.error('Load project info error:', error)
      message.error('项目不存在或已被删除')
    }
  }

  // 验证密码
  const handleVerifyPassword = async () => {
    if (!password.trim()) {
      message.warning('请输入访问密码')
      return
    }

    try {
      await verifyAccessPassword(projectId, password)
      setAccessPassword(password)
      setPasswordModalVisible(false)
      loadFileTree(password)
      message.success('验证成功')
    } catch (error) {
      message.error('访问密码错误')
    }
  }

  // 加载文件树
  const loadFileTree = async (pwd = null) => {
    try {
      const res = await getPreviewTree(projectId, pwd || accessPassword)
      const tree = res.data || []
      setFileTree(tree)

      // 默认打开 README.md
      const readmeNode = findReadme(tree)
      if (readmeNode) {
        setSelectedFile(readmeNode.key)
        loadMarkdown(readmeNode.key, pwd || accessPassword)
      }
    } catch (error) {
      console.error('Load file tree error:', error)
      if (error.response?.status === 403) {
        message.error('访问密码错误或已过期')
        setPasswordModalVisible(true)
      }
    }
  }

  // 查找根目录的 README.md
  const findReadme = (nodes) => {
    for (const node of nodes) {
      if (node.title === 'README.md' && node.isLeaf) {
        return node
      }
    }
    return null
  }

  // 转换文件树为菜单项
  const convertTreeToMenuItems = (nodes) => {
    return nodes.map((node) => {
      if (!node.isLeaf) {
        return {
          key: node.key,
          label: node.title,
          icon: <FolderOutlined />,
          children: node.children ? convertTreeToMenuItems(node.children) : [],
        }
      } else if (node.title && node.title.endsWith('.md')) {
        return {
          key: node.key,
          label: node.title.replace('.md', ''),
          icon: <FileTextOutlined />,
        }
      } else if (node.title && node.title.endsWith('.pdf')) {
        return {
          key: node.key,
          label: node.title,
          icon: <FilePdfOutlined style={{ color: '#f5222d' }} />,
        }
      }
      return null
    }).filter(Boolean)
  }

  // 加载 markdown 文件
  const loadMarkdown = async (filePath, pwd = null) => {
    setLoading(true)
    setTocItems([])
    try {
      const res = await getPreviewFile(projectId, filePath, pwd || accessPassword)
      setMarkdownContent(res.data?.content || '')

      // 移动端自动关闭侧边栏
      if (isMobile) {
        setMobileDrawerVisible(false)
      }

      // 滚动到顶部
      if (contentRef.current) {
        contentRef.current.scrollTo({ top: 0, behavior: 'smooth' })
      }
    } catch (error) {
      console.error('Load markdown error:', error)
      if (error.response?.status === 403) {
        message.error('访问密码错误或已过期')
        setPasswordModalVisible(true)
      } else {
        setMarkdownContent('# 文档加载失败\n\n无法加载该文档，请稍后重试。')
      }
    } finally {
      setLoading(false)
    }
  }

  // 提取 markdown 标题生成目录
  useEffect(() => {
    if (markdownContent) {
      const headings = []
      const lines = markdownContent.split('\n')

      lines.forEach((line) => {
        const match = line.match(/^(#{1,6})\s+(.+)$/)
        if (match) {
          const level = match[1].length
          const title = match[2]
          const key = title.toLowerCase().replace(/[^a-z0-9\u4e00-\u9fa5]+/g, '-')

          headings.push({
            key: `#${key}`,
            href: `#${key}`,
            title,
            level,
          })
        }
      })

      setTocItems(headings)
    }
  }, [markdownContent])
  // 解析相对路径
  const resolveRelativePath = (currentPath, relativePath) => {
    if (relativePath.startsWith('/')) {
      return relativePath.substring(1)
    }

    const lastSlashIndex = currentPath.lastIndexOf('/')
    const currentDir = lastSlashIndex !== -1 ? currentPath.substring(0, lastSlashIndex) : ''

    const parts = relativePath.split('/')
    const dirParts = currentDir ? currentDir.split('/') : []

    for (const part of parts) {
      if (part === '..') {
        dirParts.pop()
      } else if (part !== '.' && part !== '') {
        dirParts.push(part)
      }
    }

    return dirParts.join('/')
  }

  // 处理 markdown 内部链接点击
  const handleMarkdownLink = (e, href) => {
    if (!href || href.startsWith('http') || href.startsWith('//') || href.startsWith('#')) {
      return
    }

    const isMd = href.endsWith('.md')
    const isPdf = href.toLowerCase().endsWith('.pdf')

    if (!isMd && !isPdf) return

    e.preventDefault()

    let decodedHref = href
    try {
      decodedHref = decodeURIComponent(href)
    } catch (err) {
      // ignore
    }

    const targetPath = resolveRelativePath(selectedFile, decodedHref)

    const lastSlashIndex = targetPath.lastIndexOf('/')
    const parentPath = lastSlashIndex !== -1 ? targetPath.substring(0, lastSlashIndex) : ''
    if (parentPath && !openKeys.includes(parentPath)) {
      const pathParts = parentPath.split('/')
      const allParentPaths = []
      let currentPath = ''
      for (const part of pathParts) {
        currentPath = currentPath ? `${currentPath}/${part}` : part
        allParentPaths.push(currentPath)
      }
      setOpenKeys([...new Set([...openKeys, ...allParentPaths])])
    }

    handleMenuClick({ key: targetPath })
  }

  // 处理菜单点击
  const handleMenuClick = ({ key }) => {
    setSelectedFile(key)

    // 检查是否是PDF文件
    if (key.toLowerCase().endsWith('.pdf')) {
      // 显示PDF - 使用预览API，添加必要的参数
      let url = getPreviewDocumentUrl(projectId, key)
      const params = []

      // 如果有密码，添加密码参数
      if (accessPassword) {
        params.push(`access_pass=${encodeURIComponent(accessPassword)}`)
      }

      // 如果用户已登录（私密项目需要），添加token参数
      const token = localStorage.getItem('access_token')
      if (token) {
        params.push(`token=${encodeURIComponent(token)}`)
      }

      if (params.length > 0) {
        url += `?${params.join('&')}`
      }

      setPdfUrl(url)
      setPdfFilename(key.split('/').pop())
      setViewMode('pdf')
    } else {
      // 加载Markdown文件
      setViewMode('markdown')
      loadMarkdown(key)
    }
  }

  const menuItems = convertTreeToMenuItems(fileTree)

  // 侧边栏内容
  const SiderContent = () => (
    <>
      <div className="preview-sider-header">
        <h2>{projectInfo?.name || '项目预览'}</h2>
        {projectInfo?.description && (
          <p className="preview-project-desc">{projectInfo.description}</p>
        )}
      </div>
      <Menu
        mode="inline"
        selectedKeys={[selectedFile]}
        openKeys={openKeys}
        onOpenChange={setOpenKeys}
        items={menuItems}
        onClick={handleMenuClick}
        className="preview-menu"
      />
    </>
  )

  return (
    <div className="preview-page">
      <Layout className="preview-layout">
        {/* 移动端使用 Drawer，桌面端使用 Sider */}
        {isMobile ? (
          <>
            <Button
              type="primary"
              icon={<MenuOutlined />}
              className="mobile-menu-btn"
              onClick={() => setMobileDrawerVisible(true)}
            >
              文档索引
            </Button>
            <Drawer
              title={projectInfo?.name || '项目预览'}
              placement="left"
              onClose={() => setMobileDrawerVisible(false)}
              open={mobileDrawerVisible}
              width="80%"
            >
              <Menu
                mode="inline"
                selectedKeys={[selectedFile]}
                openKeys={openKeys}
                onOpenChange={setOpenKeys}
                items={menuItems}
                onClick={handleMenuClick}
                className="preview-menu"
              />
            </Drawer>
          </>
        ) : (
          <Sider
            width={280}
            className="preview-sider"
            theme="light"
            collapsed={siderCollapsed}
            collapsedWidth={0}
          >
            <SiderContent />
          </Sider>
        )}

        {/* 右侧内容区 */}
        <Layout className="preview-content-layout">
          <Content className="preview-content" ref={contentRef}>
            <div className={`preview-content-wrapper ${viewMode === 'pdf' ? 'pdf-mode' : ''}`}>
              {loading ? (
                <div className="preview-loading">
                  <Spin size="large">
                    <div style={{ marginTop: 16 }}>加载中...</div>
                  </Spin>
                </div>
              ) : viewMode === 'pdf' ? (
                <VirtualPDFViewer
                  url={pdfUrl}
                  filename={pdfFilename}
                />
              ) : (
                <div className="markdown-body">
                  <ReactMarkdown
                    remarkPlugins={[remarkGfm]}
                    rehypePlugins={[rehypeRaw, rehypeSlug, rehypeHighlight]}
                    components={{
                      a: ({ node, href, children, ...props }) => (
                        <a
                          href={href}
                          onClick={(e) => handleMarkdownLink(e, href)}
                          {...props}
                        >
                          {children}
                        </a>
                      ),
                    }}
                  >
                    {markdownContent}
                  </ReactMarkdown>
                </div>
              )}
            </div>

            {/* 返回顶部按钮 - 仅在markdown模式显示 */}
            {viewMode === 'markdown' && (
              <FloatButton
                icon={<VerticalAlignTopOutlined />}
                type="primary"
                style={{ right: tocCollapsed || isMobile ? 24 : 280 }}
                onClick={() => {
                  if (contentRef.current) {
                    contentRef.current.scrollTo({ top: 0, behavior: 'smooth' })
                  }
                }}
              />
            )}
          </Content>

          {/* 右侧TOC面板（仅桌面端且markdown模式显示） */}
          {!isMobile && viewMode === 'markdown' && !tocCollapsed && (
            <Sider width={250} theme="light" className="preview-toc-sider">
              <div className="toc-header">
                <h3>文档索引</h3>
                <Button
                  type="text"
                  size="small"
                  icon={<MenuFoldOutlined />}
                  onClick={() => setTocCollapsed(true)}
                />
              </div>
              <div className="toc-content">
                {tocItems.length > 0 ? (
                  <Anchor
                    affix={false}
                    offsetTop={0}
                    getContainer={() => contentRef.current}
                    items={tocItems.map((item) => ({
                      key: item.key,
                      href: item.href,
                      title: (
                        <div style={{ paddingLeft: `${(item.level - 1) * 12}px`, display: 'flex', alignItems: 'center', gap: '4px' }}>
                          <FileTextOutlined style={{ fontSize: '12px', color: '#8c8c8c' }} />
                          {item.title}
                        </div>
                      ),
                    }))}
                  />
                ) : (
                  <div className="toc-empty">当前文档无标题</div>
                )}
              </div>
            </Sider>
          )}
        </Layout>

        {/* TOC展开按钮（仅桌面端） */}
        {!isMobile && tocCollapsed && (
          <Button
            type="primary"
            icon={<MenuUnfoldOutlined />}
            className="toc-toggle-btn"
            onClick={() => setTocCollapsed(false)}
          >
            文档索引
          </Button>
        )}
      </Layout>

      {/* 密码验证模态框 */}
      <Modal
        title={
          <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
            <LockOutlined />
            <span>访问验证</span>
          </div>
        }
        open={passwordModalVisible}
        onOk={handleVerifyPassword}
        onCancel={() => setPasswordModalVisible(false)}
        okText="验证"
        cancelText="取消"
        maskClosable={false}
      >
        <div style={{ marginTop: 16 }}>
          <p>该项目需要访问密码，请输入密码后继续浏览。</p>
          <Input.Password
            placeholder="请输入访问密码"
            value={password}
            onChange={(e) => setPassword(e.target.value)}
            onPressEnter={handleVerifyPassword}
            prefix={<LockOutlined />}
          />
        </div>
      </Modal>
    </div>
  )
}

export default PreviewPage