feat: import markdown-it-plugins from https://github.com/hedgedoc/markdown-it-plugins

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

markdown-it-plugins/src/toc/plugin.ts

@@ -0,0 +1,157 @@
+/*
+ * SPDX-FileCopyrightText: Original: (c) 2018 Fabio Zendhi Nagao / Modifications: (c) 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+import { Optional } from '@mrdrogdrog/optional'
+import { encode as htmlencode } from 'html-entities'
+import MarkdownIt from 'markdown-it'
+import StateBlock from 'markdown-it/lib/rules_block/state_block.js'
+import Token from 'markdown-it/lib/token.js'
+import { TocAst } from './toc-ast.js'
+import { renderAstToHtml } from './toc-body-renderer.js'
+import { defaultOptions, TocOptions } from './toc-options.js'
+
+class Plugin {
+  private readonly tocOptions: TocOptions
+  private currentAst?: TocAst
+  public readonly START_LEVEL_ATTRIBUTE_NAME = 'startLevel'
+  public readonly END_LEVEL_ATTRIBUTE_NAME = 'endLevel'
+
+  private readonly TOC_PLACEHOLDER = /^\[\[toc(?::(\d+):(\d+))?]]|\[toc(?::(\d+):(\d+))?]$/i
+
+  public constructor(md: MarkdownIt, tocOptions?: Partial<TocOptions>) {
+    this.tocOptions = {
+      ...defaultOptions,
+      ...tocOptions
+    }
+    md.renderer.rules.tocOpen = this.renderTocOpen.bind(this)
+    md.renderer.rules.tocClose = this.renderTocClose.bind(this)
+    md.renderer.rules.tocBody = this.renderTocBody.bind(this)
+    md.core.ruler.push('generateTocAst', (state) => this.generateTocAst(state.tokens))
+    md.block.ruler.before('heading', 'toc', this.generateTocToken.bind(this), {
+      alt: ['paragraph', 'reference', 'blockquote']
+    })
+  }
+
+  private generateTocToken(state: StateBlock, startLine: number, _endLine: number, silent: boolean): boolean {
+    const pos = state.bMarks[startLine] + state.tShift[startLine]
+    const max = state.eMarks[startLine]
+
+    // use whitespace as a line tokenizer and extract the first token
+    // to test against the placeholder anchored pattern, rejecting if false
+    const lineFirstToken = state.src.slice(pos, max).split(' ')[0]
+
+    const matches = this.TOC_PLACEHOLDER.exec(lineFirstToken)
+    if (matches === null) {
+      return false
+    }
+
+    if (silent) {
+      return true
+    }
+
+    state.line = startLine + 1
+    const tocOpenToken = state.push('tocOpen', 'nav', 1)
+    tocOpenToken.markup = ''
+    tocOpenToken.map = [startLine, state.line]
+
+    const tocBodyToken = state.push('tocBody', '', 0)
+    tocBodyToken.markup = ''
+    tocBodyToken.map = [startLine, state.line]
+    tocBodyToken.children = []
+
+    const startLevel = matches[3]
+    const endLevel = matches[4]
+    if (startLevel !== undefined && endLevel !== undefined) {
+      tocBodyToken.attrSet(this.START_LEVEL_ATTRIBUTE_NAME, startLevel)
+      tocBodyToken.attrSet(this.END_LEVEL_ATTRIBUTE_NAME, endLevel)
+    }
+
+    const tocCloseToken = state.push('tocClose', 'nav', -1)
+    tocCloseToken.markup = ''
+
+    return true
+  }
+
+  private generateTocAst(tokens: Token[]) {
+    this.currentAst = this.headings2ast(tokens)
+    this.tocOptions.callback?.(this.currentAst)
+  }
+
+  private renderTocOpen(): string {
+    const id = this.tocOptions.containerId ? ` id="${htmlencode(this.tocOptions.containerId)}"` : ''
+    return `<nav${id} class="${htmlencode(this.tocOptions.containerClass)}">`
+  }
+
+  private renderTocClose(): string {
+    return '</nav>'
+  }
+
+  private createNumberRangeArray(from: number, to: number): number[] {
+    return Array.from(Array(to - from + 1).keys()).map((value) => value + from)
+  }
+
+  private renderTocBody(tokens: Token[], index: number): string {
+    const bodyToken = tokens[index]
+    const startLevel = Optional.ofNullable(bodyToken?.attrGet(this.START_LEVEL_ATTRIBUTE_NAME))
+      .map(parseInt)
+      .filter(isFinite)
+      .orElse(null)
+    const endLevel = Optional.ofNullable(bodyToken?.attrGet(this.END_LEVEL_ATTRIBUTE_NAME))
+      .map(parseInt)
+      .filter(isFinite)
+      .orElse(null)
+
+    const modifiedTocOptions =
+      startLevel !== null && endLevel !== null && startLevel <= endLevel
+        ? { ...this.tocOptions, level: this.createNumberRangeArray(startLevel, endLevel) }
+        : this.tocOptions
+
+    return this.currentAst ? renderAstToHtml(this.currentAst, modifiedTocOptions) : ''
+  }
+
+  private headings2ast(tokens: Token[]): TocAst {
+    const ast: TocAst = { level: 0, name: '', children: [] }
+    const stack = [ast]
+
+    for (let tokenIndex = 0; tokenIndex < tokens.length; tokenIndex++) {
+      const token = tokens[tokenIndex]
+      if (token.type !== 'heading_open') {
+        continue
+      }
+      const nextToken = tokens[tokenIndex + 1]
+      const key = (nextToken?.children ?? [])
+        .filter((token) => this.tocOptions.allowedTokenTypes.includes(token.type))
+        .reduce((s, t) => s + t.content, '')
+
+      const node: TocAst = {
+        level: parseInt(token.tag.slice(1), 10),
+        name: key,
+        children: []
+      }
+      if (node.level > stack[0].level) {
+        stack[0].children.push(node)
+        stack.unshift(node)
+      } else if (node.level === stack[0].level) {
+        stack[1].children.push(node)
+        stack[0] = node
+      } else {
+        while (node.level <= stack[0].level) stack.shift()
+        stack[0].children.push(node)
+        stack.unshift(node)
+      }
+    }
+
+    return ast
+  }
+}
+
+/**
+ * Creates a new TOC plugin.
+ *
+ * @param md The markdown-it instance that should be configured
+ * @param options The additional options that configure the plugin
+ */
+export const toc: MarkdownIt.PluginWithOptions<Partial<TocOptions>> = (md, options) => new Plugin(md, options)