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

   1 import { Injectable } from '@angular/core'
   2 import { buildVideoLink } from '../../../assets/player/utils'
   3 import { HtmlRendererService } from '@app/shared/renderer/html-renderer.service'
   4 import * as MarkdownIt from 'markdown-it'
   5
   6 type MarkdownParsers = {
   7   textMarkdownIt: MarkdownIt
   8   textWithHTMLMarkdownIt: MarkdownIt
   9
  10   enhancedMarkdownIt: MarkdownIt
  11   enhancedWithHTMLMarkdownIt: MarkdownIt
  12
  13   completeMarkdownIt: MarkdownIt
  14 }
  15
  16 type MarkdownConfig = {
  17   rules: string[]
  18   html: boolean
  19   escape?: boolean
  20 }
  21
  22 type MarkdownParserConfigs = {
  23   [id in keyof MarkdownParsers]: MarkdownConfig
  24 }
  25
  26 @Injectable()
  27 export class MarkdownService {
  28   static TEXT_RULES = [
  29     'linkify',
  30     'autolink',
  31     'emphasis',
  32     'link',
  33     'newline',
  34     'list'
  35   ]
  36   static TEXT_WITH_HTML_RULES = MarkdownService.TEXT_RULES.concat([ 'html_inline', 'html_block' ])
  37
  38   static ENHANCED_RULES = MarkdownService.TEXT_RULES.concat([ 'image' ])
  39   static ENHANCED_WITH_HTML_RULES = MarkdownService.TEXT_WITH_HTML_RULES.concat([ 'image' ])
  40
  41   static COMPLETE_RULES = MarkdownService.ENHANCED_WITH_HTML_RULES.concat([ 'block', 'inline', 'heading', 'paragraph' ])
  42
  43   private markdownParsers: MarkdownParsers = {
  44     textMarkdownIt: null,
  45     textWithHTMLMarkdownIt: null,
  46     enhancedMarkdownIt: null,
  47     enhancedWithHTMLMarkdownIt: null,
  48     completeMarkdownIt: null
  49   }
  50   private parsersConfig: MarkdownParserConfigs = {
  51     textMarkdownIt: { rules: MarkdownService.TEXT_RULES, html: false },
  52     textWithHTMLMarkdownIt: { rules: MarkdownService.TEXT_WITH_HTML_RULES, html: true, escape: true },
  53
  54     enhancedMarkdownIt: { rules: MarkdownService.ENHANCED_RULES, html: false },
  55     enhancedWithHTMLMarkdownIt: { rules: MarkdownService.ENHANCED_WITH_HTML_RULES, html: true, escape: true },
  56
  57     completeMarkdownIt: { rules: MarkdownService.COMPLETE_RULES, html: true }
  58   }
  59
  60   constructor (private htmlRenderer: HtmlRendererService) {}
  61
  62   textMarkdownToHTML (markdown: string, withHtml = false) {
  63     if (withHtml) return this.render('textWithHTMLMarkdownIt', markdown)
  64
  65     return this.render('textMarkdownIt', markdown)
  66   }
  67
  68   enhancedMarkdownToHTML (markdown: string, withHtml = false) {
  69     if (withHtml) return this.render('enhancedWithHTMLMarkdownIt', markdown)
  70
  71     return this.render('enhancedMarkdownIt', markdown)
  72   }
  73
  74   completeMarkdownToHTML (markdown: string) {
  75     return this.render('completeMarkdownIt', markdown)
  76   }
  77
  78   async processVideoTimestamps (html: string) {
  79     return html.replace(/((\d{1,2}):)?(\d{1,2}):(\d{1,2})/g, function (str, _, h, m, s) {
  80       const t = (3600 * +(h || 0)) + (60 * +(m || 0)) + (+(s || 0))
  81       const url = buildVideoLink({ startTime: t })
  82       return `<a class="video-timestamp" href="${url}">${str}</a>`
  83     })
  84   }
  85
  86   private async render (name: keyof MarkdownParsers, markdown: string) {
  87     if (!markdown) return ''
  88
  89     const config = this.parsersConfig[ name ]
  90     if (!this.markdownParsers[ name ]) {
  91       this.markdownParsers[ name ] = await this.createMarkdownIt(config)
  92     }
  93
  94     let html = this.markdownParsers[ name ].render(markdown)
  95     html = this.avoidTruncatedTags(html)
  96
  97     if (config.escape) return this.htmlRenderer.toSafeHtml(html)
  98
  99     return html
 100   }
 101
 102   private async createMarkdownIt (config: MarkdownConfig) {
 103     // FIXME: import('...') returns a struct module, containing a "default" field
 104     const MarkdownItClass: typeof import ('markdown-it') = (await import('markdown-it') as any).default
 105
 106     const markdownIt = new MarkdownItClass('zero', { linkify: true, breaks: true, html: config.html })
 107
 108     for (const rule of config.rules) {
 109       markdownIt.enable(rule)
 110     }
 111
 112     this.setTargetToLinks(markdownIt)
 113
 114     return markdownIt
 115   }
 116
 117   private setTargetToLinks (markdownIt: MarkdownIt) {
 118     // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer
 119     const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) {
 120       return self.renderToken(tokens, idx, options)
 121     }
 122
 123     markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) {
 124       const token = tokens[index]
 125
 126       const targetIndex = token.attrIndex('target')
 127       if (targetIndex < 0) token.attrPush([ 'target', '_blank' ])
 128       else token.attrs[targetIndex][1] = '_blank'
 129
 130       const relIndex = token.attrIndex('rel')
 131       if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ])
 132       else token.attrs[relIndex][1] = 'noopener noreferrer'
 133
 134       // pass token to default renderer.
 135       return defaultRender(tokens, index, options, env, self)
 136     }
 137   }
 138
 139   private avoidTruncatedTags (html: string) {
 140     return html.replace(/\*\*?([^*]+)$/, '$1')
 141       .replace(/<a[^>]+>([^<]+)<\/a>\s*...((<\/p>)|(<\/li>)|(<\/strong>))?$/mi, '$1...')
 142       .replace(/\[[^\]]+\]\(([^\)]+)$/m, '$1')
 143       .replace(/\s?\[[^\]]+\]?[.]{3}<\/p>$/m, '...</p>')
 144   }
 145 }