client/src/app/videos/shared/markdown.service.ts

   1 import { Injectable } from '@angular/core'
   2
   3 import * as MarkdownIt from 'markdown-it'
   4
   5 @Injectable()
   6 export class MarkdownService {
   7   private markdownIt: MarkdownIt.MarkdownIt
   8   private linkifier: MarkdownIt.MarkdownIt
   9
  10   constructor () {
  11     this.markdownIt = new MarkdownIt('zero', { linkify: true, breaks: true })
  12       .enable('linkify')
  13       .enable('autolink')
  14       .enable('emphasis')
  15       .enable('link')
  16       .enable('newline')
  17       .enable('list')
  18     this.setTargetToLinks(this.markdownIt)
  19
  20     this.linkifier = new MarkdownIt('zero', { linkify: true })
  21       .enable('linkify')
  22     this.setTargetToLinks(this.linkifier)
  23   }
  24
  25   markdownToHTML (markdown: string) {
  26     const html = this.markdownIt.render(markdown)
  27
  28     // Avoid linkify truncated links
  29     return html.replace(/<a[^>]+>([^<]+)<\/a>\s*...(<\/p>)?$/mi, '$1...')
  30   }
  31
  32   linkify (text: string) {
  33     return this.linkifier.render(text)
  34   }
  35
  36   private setTargetToLinks (markdownIt: MarkdownIt.MarkdownIt) {
  37     // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer
  38     const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) {
  39       return self.renderToken(tokens, idx, options)
  40     }
  41
  42     markdownIt.renderer.rules.link_open = function (tokens, idx, options, env, self) {
  43       // If you are sure other plugins can't add `target` - drop check below
  44       const aIndex = tokens[idx].attrIndex('target')
  45
  46       if (aIndex < 0) {
  47         tokens[idx].attrPush(['target', '_blank']) // add new attribute
  48       } else {
  49         tokens[idx].attrs[aIndex][1] = '_blank'    // replace value of existing attr
  50       }
  51
  52       // pass token to default renderer.
  53       return defaultRender(tokens, idx, options, env, self)
  54     }
  55   }
  56 }