generateExtraFormats.js

const puppeteer = require('puppeteer');
const path = require('path');
const fs = require('fs');

module.exports = {
  'generate:after': generatePdfPngSvg
};

async function generatePdfPngSvg(generator) {
  const targetDir = generator.targetDir;
  const parameters = generator.templateParams;
  //all actions of this hook depend on parameters passed by the user, if non are provided we should just stop the hook
  if (!parameters) return;

  const browser = await puppeteer.launch();
  //mermaid has this strange behaviour that it generates the id of the diagram using current date which makes it totally not possible to test
  //we override date.now() here to make sure always the same number is returned, which is also fine for produciton as only one diagram will be on index.html
  browser.on('targetchanged', async target => {
    const targetPage = await target.page();
    const client = await targetPage.target().createCDPSession();
    await client.send('Runtime.evaluate', {
      expression: 'Date.now = function() { return 0; }'
    });
  });
  const page = await browser.newPage();
  await page.goto(`file://${path.join(targetDir, 'index.html')}`, {waitUntil: 'networkidle2'});
  
  if (parameters.pdf === 'true') await page.pdf({ format: 'A4', path: `${targetDir}/index.pdf` });

  if (parameters.png === 'true') {
    const clip = await page.$eval('.mermaid', svg => {
      const react = svg.getBoundingClientRect();
      return { x: Math.floor(react.left), y: Math.floor(react.top), width: Math.ceil(react.width), height: Math.ceil(react.height) };
    });
    await page.setViewport({ width: clip.x + clip.width, height: clip.y + clip.height });
    await page.screenshot({ path: `${targetDir}/index.png`, clip});
  }

  if (parameters.svg === 'true') {
    const svg = await page.$eval('.mermaid', container => container.innerHTML);
    /* eslint-disable-next-line security/detect-non-literal-fs-filename -- Safe as no value holds user input */
    fs.writeFileSync(`${targetDir}/index.svg`, svg);
  }

  browser.close();
}