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

   1 import * as MarkdownIt from 'markdown-it'
   2 import MarkdownItEmoji from 'markdown-it-emoji'
   3 import { buildVideoLink } from 'src/assets/player/utils'
   4 import { Injectable } from '@angular/core'
   5 import { HtmlRendererService } from './html-renderer.service'
   6
   7 type MarkdownParsers = {
   8   textMarkdownIt: MarkdownIt
   9   textWithHTMLMarkdownIt: MarkdownIt
  10
  11   enhancedMarkdownIt: MarkdownIt
  12   enhancedWithHTMLMarkdownIt: MarkdownIt
  13
  14   completeMarkdownIt: MarkdownIt
  15 }
  16
  17 type MarkdownConfig = {
  18   rules: string[]
  19   html: boolean
  20   escape?: boolean
  21 }
  22
  23 type MarkdownParserConfigs = {
  24   [id in keyof MarkdownParsers]: MarkdownConfig
  25 }
  26
  27 @Injectable()
  28 export class MarkdownService {
  29   static TEXT_RULES = [
  30     'linkify',
  31     'autolink',
  32     'emphasis',
  33     'link',
  34     'newline',
  35     'list'
  36   ]
  37   static TEXT_WITH_HTML_RULES = MarkdownService.TEXT_RULES.concat([ 'html_inline', 'html_block' ])
  38
  39   static ENHANCED_RULES = MarkdownService.TEXT_RULES.concat([ 'image' ])
  40   static ENHANCED_WITH_HTML_RULES = MarkdownService.TEXT_WITH_HTML_RULES.concat([ 'image' ])
  41
  42   static COMPLETE_RULES = MarkdownService.ENHANCED_WITH_HTML_RULES.concat([ 'block', 'inline', 'heading', 'paragraph' ])
  43
  44   private markdownParsers: MarkdownParsers = {
  45     textMarkdownIt: null,
  46     textWithHTMLMarkdownIt: null,
  47     enhancedMarkdownIt: null,
  48     enhancedWithHTMLMarkdownIt: null,
  49     completeMarkdownIt: null
  50   }
  51   private parsersConfig: MarkdownParserConfigs = {
  52     textMarkdownIt: { rules: MarkdownService.TEXT_RULES, html: false },
  53     textWithHTMLMarkdownIt: { rules: MarkdownService.TEXT_WITH_HTML_RULES, html: true, escape: true },
  54
  55     enhancedMarkdownIt: { rules: MarkdownService.ENHANCED_RULES, html: false },
  56     enhancedWithHTMLMarkdownIt: { rules: MarkdownService.ENHANCED_WITH_HTML_RULES, html: true, escape: true },
  57
  58     completeMarkdownIt: { rules: MarkdownService.COMPLETE_RULES, html: true }
  59   }
  60
  61   constructor (private htmlRenderer: HtmlRendererService) {}
  62
  63   textMarkdownToHTML (markdown: string, withHtml = false, withEmoji = false) {
  64     if (withHtml) return this.render('textWithHTMLMarkdownIt', markdown, withEmoji)
  65
  66     return this.render('textMarkdownIt', markdown, withEmoji)
  67   }
  68
  69   enhancedMarkdownToHTML (markdown: string, withHtml = false, withEmoji = false) {
  70     if (withHtml) return this.render('enhancedWithHTMLMarkdownIt', markdown, withEmoji)
  71
  72     return this.render('enhancedMarkdownIt', markdown, withEmoji)
  73   }
  74
  75   completeMarkdownToHTML (markdown: string) {
  76     return this.render('completeMarkdownIt', markdown, true)
  77   }
  78
  79   async processVideoTimestamps (html: string) {
  80     return html.replace(/((\d{1,2}):)?(\d{1,2}):(\d{1,2})/g, function (str, _, h, m, s) {
  81       const t = (3600 * +(h || 0)) + (60 * +(m || 0)) + (+(s || 0))
  82       const url = buildVideoLink({ startTime: t })
  83       return `<a class="video-timestamp" href="${url}">${str}</a>`
  84     })
  85   }
  86
  87   private async render (name: keyof MarkdownParsers, markdown: string, withEmoji = false) {
  88     if (!markdown) return ''
  89
  90     const config = this.parsersConfig[ name ]
  91     if (!this.markdownParsers[ name ]) {
  92       this.markdownParsers[ name ] = await this.createMarkdownIt(config)
  93
  94       if (withEmoji) {
  95         this.markdownParsers[ name ].use(MarkdownItEmoji)
  96       }
  97     }
  98
  99     let html = this.markdownParsers[ name ].render(markdown)
 100     html = this.avoidTruncatedTags(html)
 101
 102     if (config.escape) return this.htmlRenderer.toSafeHtml(html)
 103
 104     return html
 105   }
 106
 107   private async createMarkdownIt (config: MarkdownConfig) {
 108     // FIXME: import('...') returns a struct module, containing a "default" field
 109     const MarkdownItClass: typeof import ('markdown-it') = (await import('markdown-it') as any).default
 110
 111     const markdownIt = new MarkdownItClass('zero', { linkify: true, breaks: true, html: config.html })
 112
 113     for (const rule of config.rules) {
 114       markdownIt.enable(rule)
 115     }
 116
 117     this.setTargetToLinks(markdownIt)
 118
 119     return markdownIt
 120   }
 121
 122   private setTargetToLinks (markdownIt: MarkdownIt) {
 123     // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer
 124     const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) {
 125       return self.renderToken(tokens, idx, options)
 126     }
 127
 128     markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) {
 129       const token = tokens[index]
 130
 131       const targetIndex = token.attrIndex('target')
 132       if (targetIndex < 0) token.attrPush([ 'target', '_blank' ])
 133       else token.attrs[targetIndex][1] = '_blank'
 134
 135       const relIndex = token.attrIndex('rel')
 136       if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ])
 137       else token.attrs[relIndex][1] = 'noopener noreferrer'
 138
 139       // pass token to default renderer.
 140       return defaultRender(tokens, index, options, env, self)
 141     }
 142   }
 143
 144   private avoidTruncatedTags (html: string) {
 145     return html.replace(/\*\*?([^*]+)$/, '$1')
 146       .replace(/<a[^>]+>([^<]+)<\/a>\s*...((<\/p>)|(<\/li>)|(<\/strong>))?$/mi, '$1...')
 147       .replace(/\[[^\]]+\]\(([^\)]+)$/m, '$1')
 148       .replace(/\s?\[[^\]]+\]?[.]{3}<\/p>$/m, '...</p>')
 149   }
 150 }