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import flash from '~/flash';
import { sprintf, __ } from '../../locale';
// Renders diagrams and flowcharts from text using Mermaid in any element with the
// `js-render-mermaid` class.
//
// Example markup:
//
// <pre class="js-render-mermaid">
// graph TD;
// A-- > B;
// A-- > C;
// B-- > D;
// C-- > D;
// </pre>
//
// This is an arbitrary number; Can be iterated upon when suitable.
const MAX_CHAR_LIMIT = 5000;
export default function renderMermaid($els) {
if (!$els.length) return;
import(/* webpackChunkName: 'mermaid' */ 'mermaid')
.then(mermaid => {
mermaid.initialize({
// mermaid core options
mermaid: {
startOnLoad: false,
},
// mermaidAPI options
theme: 'neutral',
flowchart: {
htmlLabels: false,
},
securityLevel: 'strict',
});
$els.each((i, el) => {
// Mermaid doesn't like `<br />` tags, so collapse all like tags into `<br>`, which is parsed correctly.
const source = el.textContent.replace(/<br\s*\/>/g, '<br>');
/**
* Restrict the rendering to a certain amount of character to
* prevent mermaidjs from hanging up the entire thread and
* causing a DoS.
*/
if (source && source.length > MAX_CHAR_LIMIT) {
el.textContent = sprintf(
__(
'Cannot render the image. Maximum character count (%{charLimit}) has been exceeded.',
),
{ charLimit: MAX_CHAR_LIMIT },
);
return;
}
// Remove any extra spans added by the backend syntax highlighting.
Object.assign(el, { textContent: source });
mermaid.init(undefined, el, id => {
const svg = document.getElementById(id);
// As of https://github.com/knsv/mermaid/commit/57b780a0d,
// Mermaid will make two init callbacks:one to initialize the
// flow charts, and another to initialize the Gannt charts.
// Guard against an error caused by double initialization.
if (svg.classList.contains('mermaid')) {
return;
}
svg.classList.add('mermaid');
// pre > code > svg
svg.closest('pre').replaceWith(svg);
// We need to add the original source into the DOM to allow Copy-as-GFM
// to access it.
const sourceEl = document.createElement('text');
sourceEl.classList.add('source');
sourceEl.setAttribute('display', 'none');
sourceEl.textContent = source;
svg.appendChild(sourceEl);
});
});
})
.catch(err => {
flash(`Can't load mermaid module: ${err}`);
});
}
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