aboutsummaryrefslogtreecommitdiffhomepage
path: root/client/src/app/shared/renderer/markdown.service.ts
blob: f0c87326f4defc13f7e2987a1db3f188839e6e6f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
import { Injectable } from '@angular/core'
import { buildVideoLink } from '../../../assets/player/utils'
import { HtmlRendererService } from '@app/shared/renderer/html-renderer.service'
import * as MarkdownIt from 'markdown-it'

type MarkdownParsers = {
  textMarkdownIt: MarkdownIt
  textWithHTMLMarkdownIt: MarkdownIt

  enhancedMarkdownIt: MarkdownIt
  enhancedWithHTMLMarkdownIt: MarkdownIt

  completeMarkdownIt: MarkdownIt
}

type MarkdownConfig = {
  rules: string[]
  html: boolean
  escape?: boolean
}

type MarkdownParserConfigs = {
  [id in keyof MarkdownParsers]: MarkdownConfig
}

@Injectable()
export class MarkdownService {
  static TEXT_RULES = [
    'linkify',
    'autolink',
    'emphasis',
    'link',
    'newline',
    'list'
  ]
  static TEXT_WITH_HTML_RULES = MarkdownService.TEXT_RULES.concat([ 'html_inline', 'html_block' ])

  static ENHANCED_RULES = MarkdownService.TEXT_RULES.concat([ 'image' ])
  static ENHANCED_WITH_HTML_RULES = MarkdownService.TEXT_WITH_HTML_RULES.concat([ 'image' ])

  static COMPLETE_RULES = MarkdownService.ENHANCED_WITH_HTML_RULES.concat([ 'block', 'inline', 'heading', 'paragraph' ])

  private markdownParsers: MarkdownParsers = {
    textMarkdownIt: null,
    textWithHTMLMarkdownIt: null,
    enhancedMarkdownIt: null,
    enhancedWithHTMLMarkdownIt: null,
    completeMarkdownIt: null
  }
  private parsersConfig: MarkdownParserConfigs = {
    textMarkdownIt: { rules: MarkdownService.TEXT_RULES, html: false },
    textWithHTMLMarkdownIt: { rules: MarkdownService.TEXT_WITH_HTML_RULES, html: true, escape: true },

    enhancedMarkdownIt: { rules: MarkdownService.ENHANCED_RULES, html: false },
    enhancedWithHTMLMarkdownIt: { rules: MarkdownService.ENHANCED_WITH_HTML_RULES, html: true, escape: true },

    completeMarkdownIt: { rules: MarkdownService.COMPLETE_RULES, html: true }
  }

  constructor (private htmlRenderer: HtmlRendererService) {}

  textMarkdownToHTML (markdown: string, withHtml = false) {
    if (withHtml) return this.render('textWithHTMLMarkdownIt', markdown)

    return this.render('textMarkdownIt', markdown)
  }

  enhancedMarkdownToHTML (markdown: string, withHtml = false) {
    if (withHtml) return this.render('enhancedWithHTMLMarkdownIt', markdown)

    return this.render('enhancedMarkdownIt', markdown)
  }

  completeMarkdownToHTML (markdown: string) {
    return this.render('completeMarkdownIt', markdown)
  }

  async processVideoTimestamps (html: string) {
    return html.replace(/((\d{1,2}):)?(\d{1,2}):(\d{1,2})/g, function (str, _, h, m, s) {
      const t = (3600 * +(h || 0)) + (60 * +(m || 0)) + (+(s || 0))
      const url = buildVideoLink({ startTime: t })
      return `<a class="video-timestamp" href="${url}">${str}</a>`
    })
  }

  private async render (name: keyof MarkdownParsers, markdown: string) {
    if (!markdown) return ''

    const config = this.parsersConfig[ name ]
    if (!this.markdownParsers[ name ]) {
      this.markdownParsers[ name ] = await this.createMarkdownIt(config)
    }

    let html = this.markdownParsers[ name ].render(markdown)
    html = this.avoidTruncatedTags(html)

    if (config.escape) return this.htmlRenderer.toSafeHtml(html)

    return html
  }

  private async createMarkdownIt (config: MarkdownConfig) {
    // FIXME: import('...') returns a struct module, containing a "default" field
    const MarkdownItClass: typeof import ('markdown-it') = (await import('markdown-it') as any).default

    const markdownIt = new MarkdownItClass('zero', { linkify: true, breaks: true, html: config.html })

    for (const rule of config.rules) {
      markdownIt.enable(rule)
    }

    this.setTargetToLinks(markdownIt)

    return markdownIt
  }

  private setTargetToLinks (markdownIt: MarkdownIt) {
    // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer
    const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) {
      return self.renderToken(tokens, idx, options)
    }

    markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) {
      const token = tokens[index]

      const targetIndex = token.attrIndex('target')
      if (targetIndex < 0) token.attrPush([ 'target', '_blank' ])
      else token.attrs[targetIndex][1] = '_blank'

      const relIndex = token.attrIndex('rel')
      if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ])
      else token.attrs[relIndex][1] = 'noopener noreferrer'

      // pass token to default renderer.
      return defaultRender(tokens, index, options, env, self)
    }
  }

  private avoidTruncatedTags (html: string) {
    return html.replace(/\*\*?([^*]+)$/, '$1')
      .replace(/<a[^>]+>([^<]+)<\/a>\s*...((<\/p>)|(<\/li>)|(<\/strong>))?$/mi, '$1...')
      .replace(/\[[^\]]+\]\(([^\)]+)$/m, '$1')
      .replace(/\s?\[[^\]]+\]?[.]{3}<\/p>$/m, '...</p>')
  }
}