1 import { Injectable } from '@angular/core'
3 import { MarkdownIt } from 'markdown-it'
6 export class MarkdownService {
15 static ENHANCED_RULES = MarkdownService.TEXT_RULES.concat([ 'image' ])
17 private textMarkdownIt: MarkdownIt
18 private enhancedMarkdownIt: MarkdownIt
20 async textMarkdownToHTML (markdown: string) {
21 if (!markdown) return ''
23 if (!this.textMarkdownIt) {
24 this.textMarkdownIt = await this.createMarkdownIt(MarkdownService.TEXT_RULES)
27 const html = this.textMarkdownIt.render(markdown)
28 return this.avoidTruncatedTags(html)
31 async enhancedMarkdownToHTML (markdown: string) {
32 if (!markdown) return ''
34 if (!this.enhancedMarkdownIt) {
35 this.enhancedMarkdownIt = await this.createMarkdownIt(MarkdownService.ENHANCED_RULES)
38 const html = this.enhancedMarkdownIt.render(markdown)
39 return this.avoidTruncatedTags(html)
42 private async createMarkdownIt (rules: string[]) {
43 // FIXME: import('..') returns a struct module, containing a "default" field corresponding to our sanitizeHtml function
44 const MarkdownItClass: typeof import ('markdown-it') = (await import('markdown-it') as any).default
46 const markdownIt = new MarkdownItClass('zero', { linkify: true, breaks: true })
48 for (const rule of rules) {
49 markdownIt.enable(rule)
52 this.setTargetToLinks(markdownIt)
57 private setTargetToLinks (markdownIt: MarkdownIt) {
58 // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer
59 const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) {
60 return self.renderToken(tokens, idx, options)
63 markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) {
64 const token = tokens[index]
66 const targetIndex = token.attrIndex('target')
67 if (targetIndex < 0) token.attrPush([ 'target', '_blank' ])
68 else token.attrs[targetIndex][1] = '_blank'
70 const relIndex = token.attrIndex('rel')
71 if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ])
72 else token.attrs[relIndex][1] = 'noopener noreferrer'
74 // pass token to default renderer.
75 return defaultRender(tokens, index, options, env, self)
79 private avoidTruncatedTags (html: string) {
80 return html.replace(/\*\*?([^*]+)$/, '$1')
81 .replace(/<a[^>]+>([^<]+)<\/a>\s*...((<\/p>)|(<\/li>)|(<\/strong>))?$/mi, '$1...')
82 .replace(/\[[^\]]+\]?\(?([^\)]+)$/, '$1')