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9d9597df C |
1 | import { Injectable } from '@angular/core' |
2 | ||
41d71344 | 3 | import { MarkdownIt } from 'markdown-it' |
9d9597df C |
4 | |
5 | @Injectable() | |
6 | export class MarkdownService { | |
621d99f5 C |
7 | static TEXT_RULES = [ |
8 | 'linkify', | |
9 | 'autolink', | |
10 | 'emphasis', | |
11 | 'link', | |
12 | 'newline', | |
13 | 'list' | |
14 | ] | |
15 | static ENHANCED_RULES = MarkdownService.TEXT_RULES.concat([ 'image' ]) | |
16 | ||
41d71344 C |
17 | private textMarkdownIt: MarkdownIt |
18 | private enhancedMarkdownIt: MarkdownIt | |
9d9597df | 19 | |
41d71344 | 20 | async textMarkdownToHTML (markdown: string) { |
53055a11 | 21 | if (!markdown) return '' |
66b16caf | 22 | |
41d71344 C |
23 | if (!this.textMarkdownIt) { |
24 | this.textMarkdownIt = await this.createMarkdownIt(MarkdownService.TEXT_RULES) | |
25 | } | |
26 | ||
53055a11 | 27 | const html = this.textMarkdownIt.render(markdown) |
8eaa6d62 | 28 | return this.avoidTruncatedTags(html) |
07fa4c97 C |
29 | } |
30 | ||
41d71344 | 31 | async enhancedMarkdownToHTML (markdown: string) { |
53055a11 | 32 | if (!markdown) return '' |
07fa4c97 | 33 | |
41d71344 C |
34 | if (!this.enhancedMarkdownIt) { |
35 | this.enhancedMarkdownIt = await this.createMarkdownIt(MarkdownService.ENHANCED_RULES) | |
36 | } | |
37 | ||
53055a11 | 38 | const html = this.enhancedMarkdownIt.render(markdown) |
8eaa6d62 | 39 | return this.avoidTruncatedTags(html) |
66b16caf | 40 | } |
621d99f5 | 41 | |
41d71344 C |
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 | |
45 | ||
46 | const markdownIt = new MarkdownItClass('zero', { linkify: true, breaks: true }) | |
621d99f5 | 47 | |
c4710631 | 48 | for (const rule of rules) { |
621d99f5 C |
49 | markdownIt.enable(rule) |
50 | } | |
51 | ||
52 | this.setTargetToLinks(markdownIt) | |
53 | ||
54 | return markdownIt | |
55 | } | |
3d9eaae3 | 56 | |
41d71344 | 57 | private setTargetToLinks (markdownIt: MarkdownIt) { |
9d9597df | 58 | // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer |
3d9eaae3 | 59 | const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) { |
9d9597df C |
60 | return self.renderToken(tokens, idx, options) |
61 | } | |
62 | ||
632c5e36 C |
63 | markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) { |
64 | const token = tokens[index] | |
9d9597df | 65 | |
632c5e36 C |
66 | const targetIndex = token.attrIndex('target') |
67 | if (targetIndex < 0) token.attrPush([ 'target', '_blank' ]) | |
68 | else token.attrs[targetIndex][1] = '_blank' | |
69 | ||
70 | const relIndex = token.attrIndex('rel') | |
71 | if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ]) | |
72 | else token.attrs[relIndex][1] = 'noopener noreferrer' | |
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73 | |
74 | // pass token to default renderer. | |
632c5e36 | 75 | return defaultRender(tokens, index, options, env, self) |
9d9597df C |
76 | } |
77 | } | |
07fa4c97 | 78 | |
8eaa6d62 | 79 | private avoidTruncatedTags (html: string) { |
e182430a C |
80 | return html.replace(/\*\*?([^*]+)$/, '$1') |
81 | .replace(/<a[^>]+>([^<]+)<\/a>\s*...((<\/p>)|(<\/li>)|(<\/strong>))?$/mi, '$1...') | |
040467f5 | 82 | .replace(/\[[^\]]+\]?\(?([^\)]+)$/, '$1') |
e182430a | 83 | |
07fa4c97 | 84 | } |
9d9597df | 85 | } |