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1 | import { Injectable } from '@angular/core' |
2 | ||
3 | import * as MarkdownIt from 'markdown-it' | |
4 | ||
5 | @Injectable() | |
6 | export class MarkdownService { | |
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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 | ||
07fa4c97 | 17 | private textMarkdownIt: MarkdownIt.MarkdownIt |
07fa4c97 | 18 | private enhancedMarkdownIt: MarkdownIt.MarkdownIt |
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19 | |
20 | constructor () { | |
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21 | this.textMarkdownIt = this.createMarkdownIt(MarkdownService.TEXT_RULES) |
22 | this.enhancedMarkdownIt = this.createMarkdownIt(MarkdownService.ENHANCED_RULES) | |
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23 | } |
24 | ||
07fa4c97 | 25 | textMarkdownToHTML (markdown: string) { |
53055a11 | 26 | if (!markdown) return '' |
66b16caf | 27 | |
53055a11 | 28 | const html = this.textMarkdownIt.render(markdown) |
8eaa6d62 | 29 | return this.avoidTruncatedTags(html) |
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30 | } |
31 | ||
32 | enhancedMarkdownToHTML (markdown: string) { | |
53055a11 | 33 | if (!markdown) return '' |
07fa4c97 | 34 | |
53055a11 | 35 | const html = this.enhancedMarkdownIt.render(markdown) |
8eaa6d62 | 36 | return this.avoidTruncatedTags(html) |
66b16caf | 37 | } |
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38 | |
39 | private createMarkdownIt (rules: string[]) { | |
40 | const markdownIt = new MarkdownIt('zero', { linkify: true, breaks: true }) | |
41 | ||
42 | for (let rule of rules) { | |
43 | markdownIt.enable(rule) | |
44 | } | |
45 | ||
46 | this.setTargetToLinks(markdownIt) | |
47 | ||
48 | return markdownIt | |
49 | } | |
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50 | |
51 | private setTargetToLinks (markdownIt: MarkdownIt.MarkdownIt) { | |
9d9597df | 52 | // Snippet from markdown-it documentation: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md#renderer |
3d9eaae3 | 53 | const defaultRender = markdownIt.renderer.rules.link_open || function (tokens, idx, options, env, self) { |
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54 | return self.renderToken(tokens, idx, options) |
55 | } | |
56 | ||
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57 | markdownIt.renderer.rules.link_open = function (tokens, index, options, env, self) { |
58 | const token = tokens[index] | |
9d9597df | 59 | |
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60 | const targetIndex = token.attrIndex('target') |
61 | if (targetIndex < 0) token.attrPush([ 'target', '_blank' ]) | |
62 | else token.attrs[targetIndex][1] = '_blank' | |
63 | ||
64 | const relIndex = token.attrIndex('rel') | |
65 | if (relIndex < 0) token.attrPush([ 'rel', 'noopener noreferrer' ]) | |
66 | else token.attrs[relIndex][1] = 'noopener noreferrer' | |
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67 | |
68 | // pass token to default renderer. | |
632c5e36 | 69 | return defaultRender(tokens, index, options, env, self) |
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70 | } |
71 | } | |
07fa4c97 | 72 | |
8eaa6d62 | 73 | private avoidTruncatedTags (html: string) { |
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74 | return html.replace(/\*\*?([^*]+)$/, '$1') |
75 | .replace(/<a[^>]+>([^<]+)<\/a>\s*...((<\/p>)|(<\/li>)|(<\/strong>))?$/mi, '$1...') | |
040467f5 | 76 | .replace(/\[[^\]]+\]?\(?([^\)]+)$/, '$1') |
e182430a | 77 | |
07fa4c97 | 78 | } |
9d9597df | 79 | } |