modularize renderer (#552)

src/components/editor/app-bar/help-button/cheatsheet.tsx

@@ -1,7 +1,10 @@
-import React from 'react'
+import MarkdownIt from 'markdown-it'
+import markdownItContainer from 'markdown-it-container'
+import React, { useCallback } from 'react'
 import { Table } from 'react-bootstrap'
 import { Trans, useTranslation } from 'react-i18next'
-import { MarkdownRenderer } from '../../../markdown-renderer/markdown-renderer'
+import { BasicMarkdownRenderer } from '../../../markdown-renderer/basic-markdown-renderer'
+import { createRenderContainer, validAlertLevels } from '../../../markdown-renderer/markdown-it-plugins/alert-container'
 import { HighlightedCode } from '../../../markdown-renderer/replace-components/highlighted-fence/highlighted-code/highlighted-code'
 import './cheatsheet.scss'
 
@@ -27,6 +30,13 @@ export const Cheatsheet: React.FC = () => {
     ':smile:',
     `:::info\n${t('editor.help.cheatsheet.exampleAlert')}\n:::`
   ]
+
+  const markdownItPlugins = useCallback((md: MarkdownIt) => {
+    validAlertLevels.forEach(level => {
+      md.use(markdownItContainer, level, { render: createRenderContainer(level) })
+    })
+  }, [])
+
   return (
     <Table className="table-condensed table-cheatsheet">
       <thead>
@@ -40,14 +50,10 @@ export const Cheatsheet: React.FC = () => {
           return (
             <tr key={key}>
               <td>
-                <MarkdownRenderer
+                <BasicMarkdownRenderer
                   content={code}
                   wide={false}
-                  onTaskCheckedChange={(_) => null}
-                  onTocChange={() => false}
-                  onMetaDataChange={() => false}
-                  onFirstHeadingChange={() => false}
-                  onLineMarkerPositionChanged={() => false}
+                  onConfigureMarkdownIt={markdownItPlugins}
                 />
               </td>
               <td className={'markdown-body'}>

src/components/editor/app-bar/help-button/help-button.tsx

@@ -6,7 +6,7 @@ import { Cheatsheet } from './cheatsheet'
 import { Links } from './links'
 import { Shortcut } from './shortcuts'
 
-enum HelpTabStatus {
+export enum HelpTabStatus {
   Cheatsheet='cheatsheet.title',
   Shortcuts='shortcuts.title',
   Links='links.title'

src/components/editor/document-renderer-pane/document-render-pane.tsx

@@ -4,7 +4,8 @@ import useResizeObserver from 'use-resize-observer'
 import { TocAst } from '../../../external-types/markdown-it-toc-done-right/interface'
 import { ForkAwesomeIcon } from '../../common/fork-awesome/fork-awesome-icon'
 import { ShowIf } from '../../common/show-if/show-if'
-import { LineMarkerPosition, MarkdownRenderer } from '../../markdown-renderer/markdown-renderer'
+import { LineMarkerPosition } from '../../markdown-renderer/types'
+import { FullMarkdownRenderer } from '../../markdown-renderer/full-markdown-renderer'
 import { ScrollProps, ScrollState } from '../scroll/scroll-props'
 import { findLineMarks } from '../scroll/utils'
 import { TableOfContents } from '../table-of-contents/table-of-contents'
@@ -108,16 +109,18 @@ export const DocumentRenderPane: React.FC<DocumentRenderPaneProps & ScrollProps>
     <div className={'bg-light flex-fill pb-5 flex-row d-flex w-100 h-100 overflow-y-scroll'}
       ref={renderer} onScroll={userScroll} onMouseEnter={onMakeScrollSource}>
       <div className={'col-md'}/>
-      <MarkdownRenderer
-        className={'flex-fill mb-3'}
-        content={content}
-        onFirstHeadingChange={onFirstHeadingChange}
-        onLineMarkerPositionChanged={setLineMarks}
-        onMetaDataChange={onMetadataChange}
-        onTaskCheckedChange={onTaskCheckedChange}
-        onTocChange={(tocAst) => setTocAst(tocAst)}
-        wide={wide}
-      />
+      <div className={'bg-light flex-fill'}>
+        <FullMarkdownRenderer
+          className={'flex-fill mb-3'}
+          content={content}
+          onFirstHeadingChange={onFirstHeadingChange}
+          onLineMarkerPositionChanged={setLineMarks}
+          onMetaDataChange={onMetadataChange}
+          onTaskCheckedChange={onTaskCheckedChange}
+          onTocChange={(tocAst) => setTocAst(tocAst)}
+          wide={wide}
+        />
+      </div>
 
       <div className={'col-md'}>
         <ShowIf condition={realWidth >= 1280 && !!tocAst}>

src/components/editor/scroll/utils.ts

@@ -1,4 +1,5 @@
-import { LineMarkerPosition } from '../../markdown-renderer/markdown-renderer'
+import { LineMarkerPosition } from '../../markdown-renderer/types'
+
 export const findLineMarks = (lineMarks: LineMarkerPosition[], lineNumber: number): { lastMarkBefore: LineMarkerPosition | undefined, firstMarkAfter: LineMarkerPosition | undefined } => {
   let lastMarkBefore
   let firstMarkAfter

src/components/markdown-renderer/basic-markdown-renderer.tsx

@@ -0,0 +1,106 @@
+import MarkdownIt from 'markdown-it'
+import abbreviation from 'markdown-it-abbr'
+import definitionList from 'markdown-it-deflist'
+import emoji from 'markdown-it-emoji'
+import footnote from 'markdown-it-footnote'
+import imsize from 'markdown-it-imsize'
+import inserted from 'markdown-it-ins'
+import marked from 'markdown-it-mark'
+import subscript from 'markdown-it-sub'
+import superscript from 'markdown-it-sup'
+import React, { ReactElement, RefObject, useMemo, useRef } from 'react'
+import { Alert } from 'react-bootstrap'
+import ReactHtmlParser from 'react-html-parser'
+import { Trans } from 'react-i18next'
+import { useSelector } from 'react-redux'
+import { ApplicationState } from '../../redux'
+import { ShowIf } from '../common/show-if/show-if'
+import { combinedEmojiData } from './markdown-it-plugins/emoji/mapping'
+import { linkifyExtra } from './markdown-it-plugins/linkify-extra'
+import { MarkdownItParserDebugger } from './markdown-it-plugins/parser-debugger'
+import './markdown-renderer.scss'
+import { ComponentReplacer } from './replace-components/ComponentReplacer'
+import { AdditionalMarkdownRendererProps, LineKeys } from './types'
+import { buildTransformer } from './utils/html-react-transformer'
+import { calculateNewLineNumberMapping } from './utils/line-number-mapping'
+
+export interface BasicMarkdownRendererProps {
+  componentReplacers?: ComponentReplacer[],
+  onConfigureMarkdownIt?: (md: MarkdownIt) => void,
+  documentReference?: RefObject<HTMLDivElement>
+  onBeforeRendering?: () => void
+}
+
+export const BasicMarkdownRenderer: React.FC<BasicMarkdownRendererProps & AdditionalMarkdownRendererProps> = ({
+  className,
+  content,
+  wide,
+  componentReplacers,
+  onConfigureMarkdownIt,
+  documentReference,
+  onBeforeRendering
+}) => {
+  const maxLength = useSelector((state: ApplicationState) => state.config.maxDocumentLength)
+
+  const markdownIt = useMemo(() => {
+    const md = new MarkdownIt('default', {
+      html: true,
+      breaks: true,
+      langPrefix: '',
+      typographer: true
+    })
+
+    md.use(emoji, {
+      defs: combinedEmojiData
+    })
+    md.use(abbreviation)
+    md.use(definitionList)
+    md.use(subscript)
+    md.use(superscript)
+    md.use(inserted)
+    md.use(marked)
+    md.use(footnote)
+    md.use(imsize)
+
+    if (onConfigureMarkdownIt) {
+      onConfigureMarkdownIt(md)
+    }
+
+    md.use(linkifyExtra)
+    if (process.env.NODE_ENV !== 'production') {
+      md.use(MarkdownItParserDebugger)
+    }
+
+    return md
+  }, [onConfigureMarkdownIt])
+
+  const oldMarkdownLineKeys = useRef<LineKeys[]>()
+  const lastUsedLineId = useRef<number>(0)
+
+  const markdownReactDom: ReactElement[] = useMemo(() => {
+    if (onBeforeRendering) {
+      onBeforeRendering()
+    }
+    const trimmedContent = content.substr(0, maxLength)
+    const html: string = markdownIt.render(trimmedContent)
+    const contentLines = trimmedContent.split('\n')
+    const { lines: newLines, lastUsedLineId: newLastUsedLineId } = calculateNewLineNumberMapping(contentLines, oldMarkdownLineKeys.current ?? [], lastUsedLineId.current)
+    oldMarkdownLineKeys.current = newLines
+    lastUsedLineId.current = newLastUsedLineId
+    const transformer = componentReplacers ? buildTransformer(newLines, componentReplacers) : undefined
+    return ReactHtmlParser(html, { transform: transformer })
+  }, [onBeforeRendering, content, maxLength, markdownIt, componentReplacers])
+
+  return (
+    <div className={`${className || ''} d-flex flex-column align-items-center ${wide ? 'wider' : ''}`}>
+      <ShowIf condition={content.length > maxLength}>
+        <Alert variant='danger' dir={'auto'}>
+          <Trans i18nKey={'editor.error.limitReached.description'} values={{ maxLength }}/>
+        </Alert>
+      </ShowIf>
+      <div ref={documentReference} className={'markdown-body w-100 d-flex flex-column align-items-center'}>
+        {markdownReactDom}
+      </div>
+    </div>
+  )
+}

src/components/markdown-renderer/full-markdown-renderer.tsx

@@ -0,0 +1,227 @@
+import markdownItTaskLists from '@hedgedoc/markdown-it-task-lists'
+import yaml from 'js-yaml'
+import MarkdownIt from 'markdown-it'
+import anchor from 'markdown-it-anchor'
+import markdownItContainer from 'markdown-it-container'
+import frontmatter from 'markdown-it-front-matter'
+import mathJax from 'markdown-it-mathjax'
+import plantuml from 'markdown-it-plantuml'
+import markdownItRegex from 'markdown-it-regex'
+import toc from 'markdown-it-toc-done-right'
+import React, { useCallback, useMemo, useRef, useState } from 'react'
+import { Alert } from 'react-bootstrap'
+import { Trans } from 'react-i18next'
+import { useSelector } from 'react-redux'
+import { TocAst } from '../../external-types/markdown-it-toc-done-right/interface'
+import { ApplicationState } from '../../redux'
+import { InternalLink } from '../common/links/internal-link'
+import { ShowIf } from '../common/show-if/show-if'
+import { slugify } from '../editor/table-of-contents/table-of-contents'
+import { RawYAMLMetadata, YAMLMetaData } from '../editor/yaml-metadata/yaml-metadata'
+import { BasicMarkdownRenderer } from './basic-markdown-renderer'
+import { createRenderContainer, validAlertLevels } from './markdown-it-plugins/alert-container'
+import { firstHeaderExtractor } from './markdown-it-plugins/first-header-extractor'
+import { highlightedCode } from './markdown-it-plugins/highlighted-code'
+import { LineMarkers, lineNumberMarker } from './markdown-it-plugins/line-number-marker'
+import { plantumlError } from './markdown-it-plugins/plantuml-error'
+import { replaceAsciinemaLink } from './regex-plugins/replace-asciinema-link'
+import { replaceGistLink } from './regex-plugins/replace-gist-link'
+import { replaceLegacyGistShortCode } from './regex-plugins/replace-legacy-gist-short-code'
+import { replaceLegacySlideshareShortCode } from './regex-plugins/replace-legacy-slideshare-short-code'
+import { replaceLegacySpeakerdeckShortCode } from './regex-plugins/replace-legacy-speakerdeck-short-code'
+import { replaceLegacyVimeoShortCode } from './regex-plugins/replace-legacy-vimeo-short-code'
+import { replaceLegacyYoutubeShortCode } from './regex-plugins/replace-legacy-youtube-short-code'
+import { replacePdfShortCode } from './regex-plugins/replace-pdf-short-code'
+import { replaceQuoteExtraAuthor } from './regex-plugins/replace-quote-extra-author'
+import { replaceQuoteExtraColor } from './regex-plugins/replace-quote-extra-color'
+import { replaceQuoteExtraTime } from './regex-plugins/replace-quote-extra-time'
+import { replaceVimeoLink } from './regex-plugins/replace-vimeo-link'
+import { replaceYouTubeLink } from './regex-plugins/replace-youtube-link'
+import { AbcReplacer } from './replace-components/abc/abc-replacer'
+import { AsciinemaReplacer } from './replace-components/asciinema/asciinema-replacer'
+import { CsvReplacer } from './replace-components/csv/csv-replacer'
+import { FlowchartReplacer } from './replace-components/flow/flowchart-replacer'
+import { GistReplacer } from './replace-components/gist/gist-replacer'
+import { HighlightedCodeReplacer } from './replace-components/highlighted-fence/highlighted-fence-replacer'
+import { ImageReplacer } from './replace-components/image/image-replacer'
+import { KatexReplacer } from './replace-components/katex/katex-replacer'
+import { LinemarkerReplacer } from './replace-components/linemarker/linemarker-replacer'
+import { MermaidReplacer } from './replace-components/mermaid/mermaid-replacer'
+import { PdfReplacer } from './replace-components/pdf/pdf-replacer'
+import { PossibleWiderReplacer } from './replace-components/possible-wider/possible-wider-replacer'
+import { QuoteOptionsReplacer } from './replace-components/quote-options/quote-options-replacer'
+import { SequenceDiagramReplacer } from './replace-components/sequence-diagram/sequence-diagram-replacer'
+import { TaskListReplacer } from './replace-components/task-list/task-list-replacer'
+import { VimeoReplacer } from './replace-components/vimeo/vimeo-replacer'
+import { YoutubeReplacer } from './replace-components/youtube/youtube-replacer'
+import { useCalculateLineMarkerPosition } from './utils/calculate-line-marker-positions'
+import { AdditionalMarkdownRendererProps, LineMarkerPosition } from './types'
+import { usePostMetaDataOnChange } from './utils/use-post-meta-data-on-change'
+import { usePostTocAstOnChange } from './utils/use-post-toc-ast-on-change'
+
+export interface FullMarkdownRendererProps {
+  onFirstHeadingChange?: (firstHeading: string | undefined) => void
+  onLineMarkerPositionChanged?: (lineMarkerPosition: LineMarkerPosition[]) => void
+  onMetaDataChange?: (yamlMetaData: YAMLMetaData | undefined) => void
+  onTaskCheckedChange: (lineInMarkdown: number, checked: boolean) => void
+  onTocChange?: (ast: TocAst) => void
+}
+
+export const FullMarkdownRenderer: React.FC<FullMarkdownRendererProps & AdditionalMarkdownRendererProps> = ({
+  onFirstHeadingChange,
+  onLineMarkerPositionChanged,
+  onMetaDataChange,
+  onTaskCheckedChange,
+  onTocChange,
+  content,
+  className,
+  wide
+}) => {
+  const allReplacers = useMemo(() => {
+    return [
+      new LinemarkerReplacer(),
+      new PossibleWiderReplacer(),
+      new GistReplacer(),
+      new YoutubeReplacer(),
+      new VimeoReplacer(),
+      new AsciinemaReplacer(),
+      new AbcReplacer(),
+      new PdfReplacer(),
+      new ImageReplacer(),
+      new SequenceDiagramReplacer(),
+      new CsvReplacer(),
+      new FlowchartReplacer(),
+      new MermaidReplacer(),
+      new HighlightedCodeReplacer(),
+      new QuoteOptionsReplacer(),
+      new KatexReplacer(),
+      new TaskListReplacer(onTaskCheckedChange)
+    ]
+  }, [onTaskCheckedChange])
+
+  const [yamlError, setYamlError] = useState(false)
+
+  const plantumlServer = useSelector((state: ApplicationState) => state.config.plantumlServer)
+
+  const rawMetaRef = useRef<RawYAMLMetadata>()
+  const firstHeadingRef = useRef<string>()
+  const documentElement = useRef<HTMLDivElement>(null)
+  const currentLineMarkers = useRef<LineMarkers[]>()
+  usePostMetaDataOnChange(rawMetaRef.current, firstHeadingRef.current, onMetaDataChange, onFirstHeadingChange)
+  useCalculateLineMarkerPosition(documentElement, currentLineMarkers.current, onLineMarkerPositionChanged, documentElement.current?.offsetTop ?? 0)
+
+  const tocAst = useRef<TocAst>()
+  usePostTocAstOnChange(tocAst, onTocChange)
+
+  const configureMarkdownIt = useCallback((md: MarkdownIt): void => {
+    if (onFirstHeadingChange) {
+      md.use(firstHeaderExtractor(), {
+        firstHeaderFound: (firstHeader: string | undefined) => {
+          firstHeadingRef.current = firstHeader
+        }
+      })
+    }
+
+    if (onMetaDataChange) {
+      md.use(frontmatter, (rawMeta: string) => {
+        try {
+          const meta: RawYAMLMetadata = yaml.safeLoad(rawMeta) as RawYAMLMetadata
+          setYamlError(false)
+          rawMetaRef.current = meta
+        } catch (e) {
+          console.error(e)
+          setYamlError(true)
+        }
+      })
+    }
+    md.use(markdownItTaskLists, { lineNumber: true })
+    if (plantumlServer) {
+      md.use(plantuml, {
+        openMarker: '```plantuml',
+        closeMarker: '```',
+        server: plantumlServer
+      })
+    } else {
+      md.use(plantumlError)
+    }
+
+    if (onMetaDataChange) {
+      md.use(frontmatter, (rawMeta: string) => {
+        try {
+          const meta: RawYAMLMetadata = yaml.safeLoad(rawMeta) as RawYAMLMetadata
+          setYamlError(false)
+          rawMetaRef.current = meta
+        } catch (e) {
+          console.error(e)
+          setYamlError(true)
+          rawMetaRef.current = ({} as RawYAMLMetadata)
+        }
+      })
+    }
+    // noinspection CheckTagEmptyBody
+    md.use(anchor, {
+      permalink: true,
+      permalinkBefore: true,
+      permalinkClass: 'heading-anchor text-dark',
+      permalinkSymbol: '<i class="fa fa-link"></i>'
+    })
+    md.use(mathJax({
+      beforeMath: '<app-katex>',
+      afterMath: '</app-katex>',
+      beforeInlineMath: '<app-katex inline>',
+      afterInlineMath: '</app-katex>',
+      beforeDisplayMath: '<app-katex>',
+      afterDisplayMath: '</app-katex>'
+    }))
+    md.use(markdownItRegex, replaceLegacyYoutubeShortCode)
+    md.use(markdownItRegex, replaceLegacyVimeoShortCode)
+    md.use(markdownItRegex, replaceLegacyGistShortCode)
+    md.use(markdownItRegex, replaceLegacySlideshareShortCode)
+    md.use(markdownItRegex, replaceLegacySpeakerdeckShortCode)
+    md.use(markdownItRegex, replacePdfShortCode)
+    md.use(markdownItRegex, replaceAsciinemaLink)
+    md.use(markdownItRegex, replaceYouTubeLink)
+    md.use(markdownItRegex, replaceVimeoLink)
+    md.use(markdownItRegex, replaceGistLink)
+    md.use(highlightedCode)
+    md.use(markdownItRegex, replaceQuoteExtraAuthor)
+    md.use(markdownItRegex, replaceQuoteExtraColor)
+    md.use(markdownItRegex, replaceQuoteExtraTime)
+    md.use(toc, {
+      placeholder: '(\\[TOC\\]|\\[toc\\])',
+      listType: 'ul',
+      level: [1, 2, 3],
+      callback: (code: string, ast: TocAst): void => {
+        tocAst.current = ast
+      },
+      slugify: slugify
+    })
+    validAlertLevels.forEach(level => {
+      md.use(markdownItContainer, level, { render: createRenderContainer(level) })
+    })
+    md.use(lineNumberMarker(), {
+      postLineMarkers: (lineMarkers) => {
+        currentLineMarkers.current = lineMarkers
+      }
+    })
+  }, [onFirstHeadingChange, onMetaDataChange, plantumlServer])
+
+  const clearMetadata = useCallback(() => {
+    rawMetaRef.current = undefined
+  }, [])
+
+  return (
+    <div className={'position-relative'}>
+      <ShowIf condition={yamlError}>
+        <Alert variant='warning' dir='auto'>
+          <Trans i18nKey='editor.invalidYaml'>
+            <InternalLink text='yaml-metadata' href='/n/yaml-metadata' className='text-dark'/>
+          </Trans>
+        </Alert>
+      </ShowIf>
+      <BasicMarkdownRenderer className={className} wide={wide} content={content} componentReplacers={allReplacers}
+        onConfigureMarkdownIt={configureMarkdownIt} documentReference={documentElement}
+        onBeforeRendering={clearMetadata}/>
+    </div>
+  )
+}

src/components/markdown-renderer/markdown-it-plugins/emoji/mapping.ts

@@ -0,0 +1,36 @@
+import emojiData from 'emoji-mart/data/twitter.json'
+import { Data } from 'emoji-mart/dist-es/utils/data'
+import { ForkAwesomeIcons } from '../../../editor/editor-pane/tool-bar/emoji-picker/icon-names'
+
+export const markdownItTwitterEmojis = Object.keys((emojiData as unknown as Data).emojis)
+  .reduce((reduceObject, emojiIdentifier) => {
+    const emoji = (emojiData as unknown as Data).emojis[emojiIdentifier]
+    const emojiCodes = emoji.unified ?? emoji.b
+    if (emojiCodes) {
+      reduceObject[emojiIdentifier] = emojiCodes.split('-').map(char => `&#x${char};`).join('')
+    }
+    return reduceObject
+  }, {} as { [key: string]: string })
+
+export const emojiSkinToneModifierMap = [2, 3, 4, 5, 6]
+  .reduce((reduceObject, modifierValue) => {
+    const lightSkinCode = 127995
+    const codepoint = lightSkinCode + (modifierValue - 2)
+    const shortcode = `skin-tone-${modifierValue}`
+    reduceObject[shortcode] = `&#${codepoint};`
+    return reduceObject
+  }, {} as { [key: string]: string })
+
+export const forkAwesomeIconMap = Object.keys(ForkAwesomeIcons)
+  .reduce((reduceObject, icon) => {
+    const shortcode = `fa-${icon}`
+    // noinspection CheckTagEmptyBody
+    reduceObject[shortcode] = `<i class="fa fa-${icon}"></i>`
+    return reduceObject
+  }, {} as { [key: string]: string })
+
+export const combinedEmojiData = {
+  ...markdownItTwitterEmojis,
+  ...emojiSkinToneModifierMap,
+  ...forkAwesomeIconMap
+}

src/components/markdown-renderer/markdown-it-plugins/first-header-extractor.ts

@@ -0,0 +1,26 @@
+import MarkdownIt from 'markdown-it/lib'
+
+export interface FirstHeaderExtractorOptions {
+  firstHeaderFound: (firstHeader: string|undefined) => void
+}
+
+export const firstHeaderExtractor: () => MarkdownIt.PluginWithOptions<FirstHeaderExtractorOptions> = () => {
+  return (md, options) => {
+    if (!options?.firstHeaderFound) {
+      return
+    }
+    md.core.ruler.after('normalize', 'extract first L1 heading', (state) => {
+      const lines = state.src.split('\n')
+      const linkAltTextRegex = /!?\[([^\]]*)]\([^)]*\)/
+      for (const line of lines) {
+        if (line.startsWith('# ')) {
+          const headerLine = line.replace('# ', '').replace(linkAltTextRegex, '$1')
+          options.firstHeaderFound(headerLine)
+          return true
+        }
+      }
+      options.firstHeaderFound(undefined)
+      return true
+    })
+  }
+}

src/components/markdown-renderer/markdown-renderer.tsx

@@ -1,398 +0,0 @@
-import emojiData from 'emoji-mart/data/twitter.json'
-import { Data } from 'emoji-mart/dist-es/utils/data'
-import equal from 'fast-deep-equal'
-import yaml from 'js-yaml'
-import MarkdownIt from 'markdown-it'
-import abbreviation from 'markdown-it-abbr'
-import anchor from 'markdown-it-anchor'
-import markdownItContainer from 'markdown-it-container'
-import definitionList from 'markdown-it-deflist'
-import emoji from 'markdown-it-emoji'
-import footnote from 'markdown-it-footnote'
-import frontmatter from 'markdown-it-front-matter'
-import imsize from 'markdown-it-imsize'
-import inserted from 'markdown-it-ins'
-import marked from 'markdown-it-mark'
-import mathJax from 'markdown-it-mathjax'
-import plantuml from 'markdown-it-plantuml'
-import markdownItRegex from 'markdown-it-regex'
-import subscript from 'markdown-it-sub'
-import superscript from 'markdown-it-sup'
-import toc from 'markdown-it-toc-done-right'
-import React, { ReactElement, useCallback, useEffect, useMemo, useRef, useState } from 'react'
-import markdownItTaskLists from '@hedgedoc/markdown-it-task-lists'
-import { Alert } from 'react-bootstrap'
-import ReactHtmlParser from 'react-html-parser'
-import { Trans } from 'react-i18next'
-import { useSelector } from 'react-redux'
-import useResizeObserver from 'use-resize-observer'
-import { TocAst } from '../../external-types/markdown-it-toc-done-right/interface'
-import { ApplicationState } from '../../redux'
-import { InternalLink } from '../common/links/internal-link'
-import { ShowIf } from '../common/show-if/show-if'
-import { ForkAwesomeIcons } from '../editor/editor-pane/tool-bar/emoji-picker/icon-names'
-import { slugify } from '../editor/table-of-contents/table-of-contents'
-import { RawYAMLMetadata, YAMLMetaData } from '../editor/yaml-metadata/yaml-metadata'
-import { createRenderContainer, validAlertLevels } from './markdown-it-plugins/alert-container'
-import { highlightedCode } from './markdown-it-plugins/highlighted-code'
-import { LineMarkers, lineNumberMarker } from './markdown-it-plugins/line-number-marker'
-import { linkifyExtra } from './markdown-it-plugins/linkify-extra'
-import { MarkdownItParserDebugger } from './markdown-it-plugins/parser-debugger'
-import { plantumlError } from './markdown-it-plugins/plantuml-error'
-import { replaceAsciinemaLink } from './regex-plugins/replace-asciinema-link'
-import { replaceGistLink } from './regex-plugins/replace-gist-link'
-import { replaceLegacyGistShortCode } from './regex-plugins/replace-legacy-gist-short-code'
-import { replaceLegacySlideshareShortCode } from './regex-plugins/replace-legacy-slideshare-short-code'
-import { replaceLegacySpeakerdeckShortCode } from './regex-plugins/replace-legacy-speakerdeck-short-code'
-import { replaceLegacyVimeoShortCode } from './regex-plugins/replace-legacy-vimeo-short-code'
-import { replaceLegacyYoutubeShortCode } from './regex-plugins/replace-legacy-youtube-short-code'
-import { replacePdfShortCode } from './regex-plugins/replace-pdf-short-code'
-import { replaceQuoteExtraAuthor } from './regex-plugins/replace-quote-extra-author'
-import { replaceQuoteExtraColor } from './regex-plugins/replace-quote-extra-color'
-import { replaceQuoteExtraTime } from './regex-plugins/replace-quote-extra-time'
-import { replaceVimeoLink } from './regex-plugins/replace-vimeo-link'
-import { replaceYouTubeLink } from './regex-plugins/replace-youtube-link'
-import { buildTransformer, calculateNewLineNumberMapping, LineKeys } from './renderer-utils'
-import { AbcReplacer } from './replace-components/abc/abc-replacer'
-import { AsciinemaReplacer } from './replace-components/asciinema/asciinema-replacer'
-import { LinemarkerReplacer } from './replace-components/linemarker/linemarker-replacer'
-import { ComponentReplacer } from './replace-components/ComponentReplacer'
-import { CsvReplacer } from './replace-components/csv/csv-replacer'
-import { FlowchartReplacer } from './replace-components/flow/flowchart-replacer'
-import { GistReplacer } from './replace-components/gist/gist-replacer'
-import { HighlightedCodeReplacer } from './replace-components/highlighted-fence/highlighted-fence-replacer'
-import { ImageReplacer } from './replace-components/image/image-replacer'
-import { KatexReplacer } from './replace-components/katex/katex-replacer'
-import { MermaidReplacer } from './replace-components/mermaid/mermaid-replacer'
-import { PdfReplacer } from './replace-components/pdf/pdf-replacer'
-import { PossibleWiderReplacer } from './replace-components/possible-wider/possible-wider-replacer'
-import { QuoteOptionsReplacer } from './replace-components/quote-options/quote-options-replacer'
-import { SequenceDiagramReplacer } from './replace-components/sequence-diagram/sequence-diagram-replacer'
-import { TaskListReplacer } from './replace-components/task-list/task-list-replacer'
-import { VimeoReplacer } from './replace-components/vimeo/vimeo-replacer'
-import { YoutubeReplacer } from './replace-components/youtube/youtube-replacer'
-import './markdown-renderer.scss'
-
-export interface LineMarkerPosition {
-  line: number
-  position: number
-}
-
-export interface MarkdownRendererProps {
-  className?: string
-  content: string
-  onFirstHeadingChange?: (firstHeading: string | undefined) => void
-  onLineMarkerPositionChanged?: (lineMarkerPosition: LineMarkerPosition[]) => void
-  onMetaDataChange?: (yamlMetaData: YAMLMetaData | undefined) => void
-  onTaskCheckedChange: (lineInMarkdown: number, checked: boolean) => void
-  onTocChange?: (ast: TocAst) => void
-  wide?: boolean
-}
-
-const markdownItTwitterEmojis = Object.keys((emojiData as unknown as Data).emojis)
-  .reduce((reduceObject, emojiIdentifier) => {
-    const emoji = (emojiData as unknown as Data).emojis[emojiIdentifier]
-    const emojiCodes = emoji.unified ?? emoji.b
-    if (emojiCodes) {
-      reduceObject[emojiIdentifier] = emojiCodes.split('-').map(char => `&#x${char};`).join('')
-    }
-    return reduceObject
-  }, {} as { [key: string]: string })
-
-const emojiSkinToneModifierMap = [2, 3, 4, 5, 6]
-  .reduce((reduceObject, modifierValue) => {
-    const lightSkinCode = 127995
-    const codepoint = lightSkinCode + (modifierValue - 2)
-    const shortcode = `skin-tone-${modifierValue}`
-    reduceObject[shortcode] = `&#${codepoint};`
-    return reduceObject
-  }, {} as { [key: string]: string })
-
-const forkAwesomeIconMap = Object.keys(ForkAwesomeIcons)
-  .reduce((reduceObject, icon) => {
-    const shortcode = `fa-${icon}`
-    // noinspection CheckTagEmptyBody
-    reduceObject[shortcode] = `<i class="fa fa-${icon}"></i>`
-    return reduceObject
-  }, {} as { [key: string]: string })
-
-export const MarkdownRenderer: React.FC<MarkdownRendererProps> = ({
-  className,
-  content,
-  onFirstHeadingChange,
-  onLineMarkerPositionChanged,
-  onMetaDataChange,
-  onTaskCheckedChange,
-  onTocChange,
-  wide
-}) => {
-  const [tocAst, setTocAst] = useState<TocAst>()
-  const maxLength = useSelector((state: ApplicationState) => state.config.maxDocumentLength)
-  const lastTocAst = useRef<TocAst>()
-  const [yamlError, setYamlError] = useState(false)
-  const rawMetaRef = useRef<RawYAMLMetadata>()
-  const oldMetaRef = useRef<RawYAMLMetadata>()
-  const firstHeadingRef = useRef<string>()
-  const oldFirstHeadingRef = useRef<string>()
-  const documentElement = useRef<HTMLDivElement>(null)
-  const lastLineMarkerPositions = useRef<LineMarkerPosition[]>()
-  const currentLineMarkers = useRef<LineMarkers[]>()
-
-  const calculateLineMarkerPositions = useCallback(() => {
-    if (!(documentElement.current && onLineMarkerPositionChanged)) {
-      return
-    }
-    if (currentLineMarkers.current === undefined) {
-      return
-    }
-    const lineMarkers = currentLineMarkers.current
-    const children: HTMLCollection = documentElement.current.children
-    const lineMarkerPositions:LineMarkerPosition[] = []
-
-    Array.from(children).forEach((child, childIndex) => {
-      const htmlChild = (child as HTMLElement)
-      if (htmlChild.offsetTop === undefined) {
-        return
-      }
-      const currentLineMarker = lineMarkers[childIndex]
-      if (currentLineMarker === undefined) {
-        return
-      }
-
-      const lastPosition = lineMarkerPositions[lineMarkerPositions.length - 1]
-      if (!lastPosition || lastPosition.line !== currentLineMarker.startLine) {
-        lineMarkerPositions.push({
-          line: currentLineMarker.startLine,
-          position: htmlChild.offsetTop
-        })
-      }
-
-      lineMarkerPositions.push({
-        line: currentLineMarker.endLine,
-        position: htmlChild.offsetTop + htmlChild.offsetHeight
-      })
-    })
-
-    if (!equal(lineMarkerPositions, lastLineMarkerPositions.current)) {
-      lastLineMarkerPositions.current = lineMarkerPositions
-      onLineMarkerPositionChanged(lineMarkerPositions)
-    }
-  }, [onLineMarkerPositionChanged])
-
-  useEffect(() => {
-    calculateLineMarkerPositions()
-  }, [calculateLineMarkerPositions, content])
-
-  useResizeObserver({
-    ref: documentElement,
-    onResize: () => calculateLineMarkerPositions()
-  })
-
-  useEffect(() => {
-    if (onMetaDataChange && !equal(oldMetaRef.current, rawMetaRef.current)) {
-      if (rawMetaRef.current) {
-        const newMetaData = new YAMLMetaData(rawMetaRef.current)
-        onMetaDataChange(newMetaData)
-      } else {
-        onMetaDataChange(undefined)
-      }
-      oldMetaRef.current = rawMetaRef.current
-    }
-    if (onFirstHeadingChange && !equal(firstHeadingRef.current, oldFirstHeadingRef.current)) {
-      onFirstHeadingChange(firstHeadingRef.current || undefined)
-      oldFirstHeadingRef.current = firstHeadingRef.current
-    }
-  })
-
-  const plantumlServer = useSelector((state: ApplicationState) => state.config.plantumlServer)
-
-  const markdownIt = useMemo(() => {
-    const md = new MarkdownIt('default', {
-      html: true,
-      breaks: true,
-      langPrefix: '',
-      typographer: true
-    })
-    if (onFirstHeadingChange) {
-      md.core.ruler.after('normalize', 'extract first L1 heading', (state) => {
-        const lines = state.src.split('\n')
-        const linkAltTextRegex = /!?\[([^\]]*)]\([^)]*\)/
-        for (const line of lines) {
-          if (line.startsWith('# ')) {
-            firstHeadingRef.current = line.replace('# ', '').replace(linkAltTextRegex, '$1')
-            return true
-          }
-        }
-        firstHeadingRef.current = undefined
-        return true
-      })
-    }
-    if (onMetaDataChange) {
-      md.use(frontmatter, (rawMeta: string) => {
-        try {
-          const meta: RawYAMLMetadata = yaml.safeLoad(rawMeta) as RawYAMLMetadata
-          setYamlError(false)
-          rawMetaRef.current = meta
-        } catch (e) {
-          console.error(e)
-          setYamlError(true)
-        }
-      })
-    }
-    md.use(markdownItTaskLists, { lineNumber: true })
-    if (plantumlServer) {
-      md.use(plantuml, {
-        openMarker: '```plantuml',
-        closeMarker: '```',
-        server: plantumlServer
-      })
-    } else {
-      md.use(plantumlError)
-    }
-    md.use(emoji, {
-      defs: {
-        ...markdownItTwitterEmojis,
-        ...emojiSkinToneModifierMap,
-        ...forkAwesomeIconMap
-      }
-    })
-    md.use(abbreviation)
-    md.use(definitionList)
-    md.use(subscript)
-    md.use(superscript)
-    md.use(inserted)
-    md.use(marked)
-    md.use(footnote)
-    if (onMetaDataChange) {
-      md.use(frontmatter, (rawMeta: string) => {
-        try {
-          const meta: RawYAMLMetadata = yaml.safeLoad(rawMeta) as RawYAMLMetadata
-          setYamlError(false)
-          rawMetaRef.current = meta
-        } catch (e) {
-          console.error(e)
-          setYamlError(true)
-          rawMetaRef.current = ({} as RawYAMLMetadata)
-        }
-      })
-    }
-    md.use(imsize)
-    // noinspection CheckTagEmptyBody
-    md.use(anchor, {
-      permalink: true,
-      permalinkBefore: true,
-      permalinkClass: 'heading-anchor text-dark',
-      permalinkSymbol: '<i class="fa fa-link"></i>'
-    })
-    md.use(mathJax({
-      beforeMath: '<app-katex>',
-      afterMath: '</app-katex>',
-      beforeInlineMath: '<app-katex inline>',
-      afterInlineMath: '</app-katex>',
-      beforeDisplayMath: '<app-katex>',
-      afterDisplayMath: '</app-katex>'
-    }))
-    md.use(markdownItRegex, replaceLegacyYoutubeShortCode)
-    md.use(markdownItRegex, replaceLegacyVimeoShortCode)
-    md.use(markdownItRegex, replaceLegacyGistShortCode)
-    md.use(markdownItRegex, replaceLegacySlideshareShortCode)
-    md.use(markdownItRegex, replaceLegacySpeakerdeckShortCode)
-    md.use(markdownItRegex, replacePdfShortCode)
-    md.use(markdownItRegex, replaceAsciinemaLink)
-    md.use(markdownItRegex, replaceYouTubeLink)
-    md.use(markdownItRegex, replaceVimeoLink)
-    md.use(markdownItRegex, replaceGistLink)
-    md.use(highlightedCode)
-    md.use(markdownItRegex, replaceQuoteExtraAuthor)
-    md.use(markdownItRegex, replaceQuoteExtraColor)
-    md.use(markdownItRegex, replaceQuoteExtraTime)
-    md.use(toc, {
-      placeholder: '(\\[TOC\\]|\\[toc\\])',
-      listType: 'ul',
-      level: [1, 2, 3],
-      callback: (code: string, ast: TocAst): void => {
-        setTocAst(ast)
-      },
-      slugify: slugify
-    })
-    md.use(linkifyExtra)
-    validAlertLevels.forEach(level => {
-      md.use(markdownItContainer, level, { render: createRenderContainer(level) })
-    })
-    md.use(lineNumberMarker(), {
-      postLineMarkers: (lineMarkers) => {
-        currentLineMarkers.current = lineMarkers
-      }
-    })
-    if (process.env.NODE_ENV !== 'production') {
-      md.use(MarkdownItParserDebugger)
-    }
-
-    return md
-  }, [onMetaDataChange, onFirstHeadingChange, plantumlServer])
-
-  useEffect(() => {
-    if (onTocChange && tocAst && !equal(tocAst, lastTocAst.current)) {
-      lastTocAst.current = tocAst
-      onTocChange(tocAst)
-    }
-  }, [tocAst, onTocChange])
-
-  const oldMarkdownLineKeys = useRef<LineKeys[]>()
-  const lastUsedLineId = useRef<number>(0)
-
-  const markdownReactDom: ReactElement[] = useMemo(() => {
-    const allReplacers: ComponentReplacer[] = [
-      new LinemarkerReplacer(),
-      new PossibleWiderReplacer(),
-      new GistReplacer(),
-      new YoutubeReplacer(),
-      new VimeoReplacer(),
-      new AsciinemaReplacer(),
-      new AbcReplacer(),
-      new PdfReplacer(),
-      new ImageReplacer(),
-      new SequenceDiagramReplacer(),
-      new CsvReplacer(),
-      new FlowchartReplacer(),
-      new MermaidReplacer(),
-      new HighlightedCodeReplacer(),
-      new QuoteOptionsReplacer(),
-      new KatexReplacer(),
-      new TaskListReplacer(onTaskCheckedChange)
-    ]
-    if (onMetaDataChange) {
-      // This is used if the front-matter callback is never called, because the user deleted everything regarding metadata from the document
-      rawMetaRef.current = undefined
-    }
-    const trimmedContent = content.substr(0, maxLength)
-    const html: string = markdownIt.render(trimmedContent)
-    const contentLines = trimmedContent.split('\n')
-    const { lines: newLines, lastUsedLineId: newLastUsedLineId } = calculateNewLineNumberMapping(contentLines, oldMarkdownLineKeys.current ?? [], lastUsedLineId.current)
-    oldMarkdownLineKeys.current = newLines
-    lastUsedLineId.current = newLastUsedLineId
-    return ReactHtmlParser(html, { transform: buildTransformer(newLines, allReplacers) })
-  }, [content, markdownIt, onMetaDataChange, onTaskCheckedChange, maxLength])
-
-  return (
-    <div className={'bg-light flex-fill'}>
-      <div className={`${className || ''} d-flex flex-column align-items-center ${wide ? 'wider' : ''}`} >
-        <ShowIf condition={yamlError}>
-          <Alert variant='warning' dir='auto'>
-            <Trans i18nKey='editor.invalidYaml'>
-              <InternalLink text='yaml-metadata' href='/n/yaml-metadata' className='text-dark'/>
-            </Trans>
-          </Alert>
-        </ShowIf>
-        <ShowIf condition={content.length > maxLength}>
-          <Alert variant='danger' dir={'auto'}>
-            <Trans i18nKey={'editor.error.limitReached.description'} values={{ maxLength }}/>
-          </Alert>
-        </ShowIf>
-        <div ref={documentElement} className={'markdown-body w-100 d-flex flex-column align-items-center'}>
-          {markdownReactDom}
-        </div>
-      </div>
-    </div>
-  )
-}

src/components/markdown-renderer/types.d.ts

@@ -0,0 +1,15 @@
+export interface LineKeys {
+  line: string,
+  id: number
+}
+
+export interface LineMarkerPosition {
+  line: number
+  position: number
+}
+
+export interface AdditionalMarkdownRendererProps {
+  className?: string,
+  content: string,
+  wide?: boolean,
+}

src/components/markdown-renderer/utils/calculate-line-marker-positions.ts

@@ -0,0 +1,63 @@
+import equal from 'fast-deep-equal'
+import { RefObject, useCallback, useEffect, useRef } from 'react'
+import useResizeObserver from 'use-resize-observer'
+import { LineMarkerPosition } from '../types'
+import { LineMarkers } from '../markdown-it-plugins/line-number-marker'
+
+export const calculateLineMarkerPositions = (documentElement: HTMLDivElement, currentLineMarkers: LineMarkers[], offset?: number): LineMarkerPosition[] => {
+  const lineMarkers = currentLineMarkers
+  const children: HTMLCollection = documentElement.children
+  const lineMarkerPositions:LineMarkerPosition[] = []
+
+  Array.from(children).forEach((child, childIndex) => {
+    const htmlChild = (child as HTMLElement)
+    if (htmlChild.offsetTop === undefined) {
+      return
+    }
+    const currentLineMarker = lineMarkers[childIndex]
+    if (currentLineMarker === undefined) {
+      return
+    }
+
+    const lastPosition = lineMarkerPositions[lineMarkerPositions.length - 1]
+    if (!lastPosition || lastPosition.line !== currentLineMarker.startLine) {
+      lineMarkerPositions.push({
+        line: currentLineMarker.startLine,
+        position: htmlChild.offsetTop + (offset ?? 0)
+      })
+    }
+
+    lineMarkerPositions.push({
+      line: currentLineMarker.endLine,
+      position: htmlChild.offsetTop + htmlChild.offsetHeight + (offset ?? 0)
+    })
+  })
+
+  return lineMarkerPositions
+}
+
+export const useCalculateLineMarkerPosition = (documentElement: RefObject<HTMLDivElement>, lineMarkers?: LineMarkers[], onLineMarkerPositionChanged?: (lineMarkerPosition: LineMarkerPosition[]) => void, offset?: number) : void => {
+  const lastLineMarkerPositions = useRef<LineMarkerPosition[]>()
+
+  const calculateNewLineMarkerPositions = useCallback(() => {
+    if (!documentElement.current || !onLineMarkerPositionChanged || !lineMarkers) {
+      return
+    }
+
+    const newLines = calculateLineMarkerPositions(documentElement.current, lineMarkers, offset)
+
+    if (!equal(newLines, lastLineMarkerPositions)) {
+      lastLineMarkerPositions.current = newLines
+      onLineMarkerPositionChanged(newLines)
+    }
+  }, [documentElement, lineMarkers, offset, onLineMarkerPositionChanged])
+
+  useEffect(() => {
+    calculateNewLineMarkerPositions()
+  }, [calculateNewLineMarkerPositions])
+
+  useResizeObserver({
+    ref: documentElement,
+    onResize: () => calculateNewLineMarkerPositions()
+  })
+}

src/components/markdown-renderer/utils/html-react-transformer.tsx

@@ -1,51 +1,17 @@
-import { diffArrays } from 'diff'
 import { DomElement } from 'domhandler'
 import React, { Fragment, ReactElement } from 'react'
 import { convertNodeToElement, Transform } from 'react-html-parser'
 import {
   ComponentReplacer,
   SubNodeTransform
-} from './replace-components/ComponentReplacer'
+} from '../replace-components/ComponentReplacer'
+import { LineKeys } from '../types'
 
 export interface TextDifferenceResult {
   lines: LineKeys[],
   lastUsedLineId: number
 }
 
-export interface LineKeys {
-  line: string,
-  id: number
-}
-
-export const calculateNewLineNumberMapping = (newMarkdownLines: string[], oldLineKeys: LineKeys[], lastUsedLineId: number): TextDifferenceResult => {
-  const lineDifferences = diffArrays<string, LineKeys>(newMarkdownLines, oldLineKeys, {
-    comparator: (left:string|LineKeys, right:string|LineKeys) => {
-      const leftLine = (left as LineKeys).line ?? (left as string)
-      const rightLine = (right as LineKeys).line ?? (right as string)
-      return leftLine === rightLine
-    }
-  })
-
-  const newLines: LineKeys[] = []
-
-  lineDifferences
-    .filter((change) => change.added === undefined || !change.added)
-    .forEach((value) => {
-      if (value.removed) {
-        (value.value as string[])
-          .forEach(line => {
-            lastUsedLineId += 1
-            newLines.push({ line: line, id: lastUsedLineId })
-          })
-      } else {
-        (value.value as LineKeys[])
-          .forEach((line) => newLines.push(line))
-      }
-    })
-
-  return { lines: newLines, lastUsedLineId: lastUsedLineId }
-}
-
 export const calculateKeyFromLineMarker = (node: DomElement, lineKeys?: LineKeys[]): number|undefined => {
   if (!node.attribs || lineKeys === undefined) {
     return

src/components/markdown-renderer/utils/line-number-mapping.ts

@@ -0,0 +1,32 @@
+import { diffArrays } from 'diff'
+import { TextDifferenceResult } from './html-react-transformer'
+import { LineKeys } from '../types'
+
+export const calculateNewLineNumberMapping = (newMarkdownLines: string[], oldLineKeys: LineKeys[], lastUsedLineId: number): TextDifferenceResult => {
+  const lineDifferences = diffArrays<string, LineKeys>(newMarkdownLines, oldLineKeys, {
+    comparator: (left:string|LineKeys, right:string|LineKeys) => {
+      const leftLine = (left as LineKeys).line ?? (left as string)
+      const rightLine = (right as LineKeys).line ?? (right as string)
+      return leftLine === rightLine
+    }
+  })
+
+  const newLines: LineKeys[] = []
+
+  lineDifferences
+    .filter((change) => change.added === undefined || !change.added)
+    .forEach((value) => {
+      if (value.removed) {
+        (value.value as string[])
+          .forEach(line => {
+            lastUsedLineId += 1
+            newLines.push({ line: line, id: lastUsedLineId })
+          })
+      } else {
+        (value.value as LineKeys[])
+          .forEach((line) => newLines.push(line))
+      }
+    })
+
+  return { lines: newLines, lastUsedLineId: lastUsedLineId }
+}

src/components/markdown-renderer/utils/use-post-meta-data-on-change.ts

@@ -0,0 +1,29 @@
+import equal from 'fast-deep-equal'
+import { useEffect, useRef } from 'react'
+import { RawYAMLMetadata, YAMLMetaData } from '../../editor/yaml-metadata/yaml-metadata'
+
+export const usePostMetaDataOnChange = (
+  rawMetaRef: RawYAMLMetadata|undefined,
+  firstHeadingRef: string|undefined,
+  onMetaDataChange?: (yamlMetaData: YAMLMetaData | undefined) => void,
+  onFirstHeadingChange?: (firstHeading: string | undefined) => void
+): void => {
+  const oldMetaRef = useRef<RawYAMLMetadata>()
+  const oldFirstHeadingRef = useRef<string>()
+
+  useEffect(() => {
+    if (onMetaDataChange && !equal(oldMetaRef.current, rawMetaRef)) {
+      if (rawMetaRef) {
+        const newMetaData = new YAMLMetaData(rawMetaRef)
+        onMetaDataChange(newMetaData)
+      } else {
+        onMetaDataChange(undefined)
+      }
+      oldMetaRef.current = rawMetaRef
+    }
+    if (onFirstHeadingChange && !equal(firstHeadingRef, oldFirstHeadingRef.current)) {
+      onFirstHeadingChange(firstHeadingRef || undefined)
+      oldFirstHeadingRef.current = firstHeadingRef
+    }
+  })
+}

src/components/markdown-renderer/utils/use-post-toc-ast-on-change.ts

@@ -0,0 +1,13 @@
+import equal from 'fast-deep-equal'
+import { RefObject, useEffect, useRef } from 'react'
+import { TocAst } from '../../../external-types/markdown-it-toc-done-right/interface'
+
+export const usePostTocAstOnChange = (tocAst: RefObject<TocAst|undefined>, onTocChange?: (ast: TocAst) => void): void => {
+  const lastTocAst = useRef<TocAst>()
+  useEffect(() => {
+    if (onTocChange && tocAst.current && !equal(tocAst, lastTocAst.current)) {
+      lastTocAst.current = tocAst.current
+      onTocChange(tocAst.current)
+    }
+  }, [onTocChange, tocAst])
+}