dify/web/app/components/base/markdown.tsx

import ReactMarkdown from 'react-markdown'
import ReactEcharts from 'echarts-for-react'
import 'katex/dist/katex.min.css'
import RemarkMath from 'remark-math'
import RemarkBreaks from 'remark-breaks'
import RehypeKatex from 'rehype-katex'
import RemarkGfm from 'remark-gfm'
import RehypeRaw from 'rehype-raw'
import SyntaxHighlighter from 'react-syntax-highlighter'
import { atelierHeathLight } from 'react-syntax-highlighter/dist/esm/styles/hljs'
import type { RefObject } from 'react'
import { Component, memo, useEffect, useMemo, useRef, useState } from 'react'
import type { CodeComponent } from 'react-markdown/lib/ast-to-react'
import cn from '@/utils/classnames'
import CopyBtn from '@/app/components/base/copy-btn'
import SVGBtn from '@/app/components/base/svg'
import Flowchart from '@/app/components/base/mermaid'
import ImageGallery from '@/app/components/base/image-gallery'
import { useChatContext } from '@/app/components/base/chat/chat/context'
import VideoGallery from '@/app/components/base/video-gallery'
import AudioGallery from '@/app/components/base/audio-gallery'
import SVGRenderer from '@/app/components/base/svg-gallery'
import MarkdownButton from '@/app/components/base/markdown-blocks/button'
import MarkdownForm from '@/app/components/base/markdown-blocks/form'

// Available language https://github.com/react-syntax-highlighter/react-syntax-highlighter/blob/master/AVAILABLE_LANGUAGES_HLJS.MD
const capitalizationLanguageNameMap: Record<string, string> = {
  sql: 'SQL',
  javascript: 'JavaScript',
  java: 'Java',
  typescript: 'TypeScript',
  vbscript: 'VBScript',
  css: 'CSS',
  html: 'HTML',
  xml: 'XML',
  php: 'PHP',
  python: 'Python',
  yaml: 'Yaml',
  mermaid: 'Mermaid',
  markdown: 'MarkDown',
  makefile: 'MakeFile',
  echarts: 'ECharts',
  shell: 'Shell',
  powershell: 'PowerShell',
  json: 'JSON',
  latex: 'Latex',
  svg: 'SVG',
}
const getCorrectCapitalizationLanguageName = (language: string) => {
  if (!language)
    return 'Plain'

  if (language in capitalizationLanguageNameMap)
    return capitalizationLanguageNameMap[language]

  return language.charAt(0).toUpperCase() + language.substring(1)
}

const preprocessLaTeX = (content: string) => {
  if (typeof content !== 'string')
    return content
  return content.replace(/\\\[(.*?)\\\]/g, (_, equation) => `$$${equation}$$`)
    .replace(/\\\((.*?)\\\)/g, (_, equation) => `$$${equation}$$`)
    .replace(/(^|[^\\])\$(.+?)\$/g, (_, prefix, equation) => `${prefix}$${equation}$`)
}

export function PreCode(props: { children: any }) {
  const ref = useRef<HTMLPreElement>(null)

  return (
    <pre ref={ref}>
      <span
        className="copy-code-button"
      ></span>
      {props.children}
    </pre>
  )
}

// eslint-disable-next-line unused-imports/no-unused-vars
const useLazyLoad = (ref: RefObject<Element>): boolean => {
  const [isIntersecting, setIntersecting] = useState<boolean>(false)

  useEffect(() => {
    const observer = new IntersectionObserver(([entry]) => {
      if (entry.isIntersecting) {
        setIntersecting(true)
        observer.disconnect()
      }
    })

    if (ref.current)
      observer.observe(ref.current)

    return () => {
      observer.disconnect()
    }
  }, [ref])

  return isIntersecting
}

// **Add code block
// Avoid error #185 (Maximum update depth exceeded.
// This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate.
// React limits the number of nested updates to prevent infinite loops.)
// Reference A: https://reactjs.org/docs/error-decoder.html?invariant=185
// Reference B1: https://react.dev/reference/react/memo
// Reference B2: https://react.dev/reference/react/useMemo
// ****
// The original error that occurred in the streaming response during the conversation:
// Error: Minified React error 185;
// visit https://reactjs.org/docs/error-decoder.html?invariant=185 for the full message
// or use the non-minified dev environment for full errors and additional helpful warnings.

const CodeBlock: CodeComponent = memo(({ inline, className, children, ...props }) => {
  const [isSVG, setIsSVG] = useState(true)
  const match = /language-(\w+)/.exec(className || '')
  const language = match?.[1]
  const languageShowName = getCorrectCapitalizationLanguageName(language || '')
  const chartData = useMemo(() => {
    if (language === 'echarts') {
      try {
        return JSON.parse(String(children).replace(/\n$/, ''))
      }
      catch (error) {}
    }
    return JSON.parse('{"title":{"text":"ECharts error - Wrong JSON format."}}')
  }, [language, children])

  const renderCodeContent = useMemo(() => {
    const content = String(children).replace(/\n$/, '')
    if (language === 'mermaid' && isSVG) {
      return <Flowchart PrimitiveCode={content} />
    }
    else if (language === 'echarts') {
      return (
        <div style={{ minHeight: '350px', minWidth: '700px' }}>
          <ErrorBoundary>
            <ReactEcharts option={chartData} />
          </ErrorBoundary>
        </div>
      )
    }
    else if (language === 'svg' && isSVG) {
      return (
        <ErrorBoundary>
          <SVGRenderer content={content} />
        </ErrorBoundary>
      )
    }
    else {
      return (
        <SyntaxHighlighter
          {...props}
          style={atelierHeathLight}
          customStyle={{
            paddingLeft: 12,
            backgroundColor: '#fff',
          }}
          language={match?.[1]}
          showLineNumbers
          PreTag="div"
        >
          {content}
        </SyntaxHighlighter>
      )
    }
  }, [language, match, props, children, chartData, isSVG])

  if (inline || !match)
    return <code {...props} className={className}>{children}</code>

  return (
    <div>
      <div
        className='flex justify-between h-8 items-center p-1 pl-3 border-b'
        style={{
          borderColor: 'rgba(0, 0, 0, 0.05)',
        }}
      >
        <div className='text-[13px] text-gray-500 font-normal'>{languageShowName}</div>
        <div style={{ display: 'flex' }}>
          {(['mermaid', 'svg']).includes(language!) && <SVGBtn isSVG={isSVG} setIsSVG={setIsSVG}/>}
          <CopyBtn
            className='mr-1'
            value={String(children).replace(/\n$/, '')}
            isPlain
          />
        </div>
      </div>
      {renderCodeContent}
    </div>
  )
})
CodeBlock.displayName = 'CodeBlock'

const VideoBlock: CodeComponent = memo(({ node }) => {
  const srcs = node.children.filter(child => 'properties' in child).map(child => (child as any).properties.src)
  if (srcs.length === 0)
    return null
  return <VideoGallery key={srcs.join()} srcs={srcs} />
})
VideoBlock.displayName = 'VideoBlock'

const AudioBlock: CodeComponent = memo(({ node }) => {
  const srcs = node.children.filter(child => 'properties' in child).map(child => (child as any).properties.src)
  if (srcs.length === 0)
    return null
  return <AudioGallery key={srcs.join()} srcs={srcs} />
})
AudioBlock.displayName = 'AudioBlock'

const Paragraph = (paragraph: any) => {
  const { node }: any = paragraph
  const children_node = node.children
  if (children_node && children_node[0] && 'tagName' in children_node[0] && children_node[0].tagName === 'img') {
    return (
      <>
        <ImageGallery srcs={[children_node[0].properties.src]} />
        <p>{paragraph.children.slice(1)}</p>
      </>
    )
  }
  return <p>{paragraph.children}</p>
}

const Img = ({ src }: any) => {
  return (<ImageGallery srcs={[src]} />)
}

const Link = ({ node, ...props }: any) => {
  if (node.properties?.href && node.properties.href?.toString().startsWith('abbr')) {
    // eslint-disable-next-line react-hooks/rules-of-hooks
    const { onSend } = useChatContext()
    const hidden_text = decodeURIComponent(node.properties.href.toString().split('abbr:')[1])

    return <abbr className="underline decoration-dashed !decoration-primary-700 cursor-pointer" onClick={() => onSend?.(hidden_text)} title={node.children[0]?.value}>{node.children[0]?.value}</abbr>
  }
  else {
    return <a {...props} target="_blank" className="underline decoration-dashed !decoration-primary-700 cursor-pointer">{node.children[0] ? node.children[0]?.value : 'Download'}</a>
  }
}

export function Markdown(props: { content: string; className?: string }) {
  const latexContent = preprocessLaTeX(props.content)
  return (
    <div className={cn(props.className, 'markdown-body')}>
      <ReactMarkdown
        remarkPlugins={[RemarkGfm, RemarkMath, RemarkBreaks]}
        rehypePlugins={[
          RehypeKatex,
          RehypeRaw as any,
          // The Rehype plug-in is used to remove the ref attribute of an element
          () => {
            return (tree) => {
              const iterate = (node: any) => {
                if (node.type === 'element' && !node.properties?.src && node.properties?.ref && node.properties.ref.startsWith('{') && node.properties.ref.endsWith('}'))
                  delete node.properties.ref

                if (node.children)
                  node.children.forEach(iterate)
              }
              tree.children.forEach(iterate)
            }
          },
        ]}
        disallowedElements={['script', 'iframe', 'head', 'html', 'meta', 'link', 'style', 'body']}
        components={{
          code: CodeBlock,
          img: Img,
          video: VideoBlock,
          audio: AudioBlock,
          a: Link,
          p: Paragraph,
          button: MarkdownButton,
          form: MarkdownForm,
        }}
        linkTarget='_blank'
      >
        {/* Markdown detect has problem. */}
        {latexContent}
      </ReactMarkdown>
    </div>
  )
}

// **Add an ECharts runtime error handler
// Avoid error #7832 (Crash when ECharts accesses undefined objects)
// This can happen when a component attempts to access an undefined object that references an unregistered map, causing the program to crash.

export default class ErrorBoundary extends Component {
  constructor(props: any) {
    super(props)
    this.state = { hasError: false }
  }

  componentDidCatch(error: any, errorInfo: any) {
    this.setState({ hasError: true })
    console.error(error, errorInfo)
  }

  render() {
    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
    // @ts-expect-error
    if (this.state.hasError)
      return <div>Oops! An error occurred. This could be due to an ECharts runtime error or invalid SVG content. <br />(see the browser console for more information)</div>
    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
    // @ts-expect-error
    return this.props.children
  }
}