changelog-to-html/src/markdown-it-changelog-plugin.js

CLI to convert a CHANGELOG.md following the http://keepachangelog.com convention to a static web page with permalinks and a GitHub look and feel

'use strict';

const path = require('path');

const fs = require('fs-extra');

const {getSlug} = require('./slug');

const permalinkIcon = String(
  // eslint-disable-next-line no-sync
  fs.readFileSync(path.join(__dirname, 'permalink.svg'))
);

const markdownItChangelogPlugin = (md, {h1TitleCb}) => {
  md.core.ruler.push('h1Title', state => {
    const {tokens} = state;
    const h1OpeningTagIndex = tokens.findIndex(
      ({tag, type}) => type === 'heading_open' && tag === 'h1'
    );
    h1TitleCb(
      h1OpeningTagIndex >= 0
        ? tokens[h1OpeningTagIndex + 1].content
        : 'Missing <h1> title'
    );
  });

  md.core.ruler.push('permalinks', state => {
    const breadcrumbs = [];
    const replacements = [];
    const {Token, tokens} = state;

    const replaceTokenWithOthers = ({replacementTokens, tokenToReplace}) => {
      const tokenToReplaceIndex = tokens.indexOf(tokenToReplace);
      if (replacementTokens.length === 0) {
        return;
      }
      const [firstToken, ...otherTokens] = replacementTokens;
      tokens.splice(tokenToReplaceIndex, 1, firstToken);
      otherTokens.forEach((token, index) => {
        tokens.splice(tokenToReplaceIndex + index + 1, 0, token);
      });
    };

    tokens.forEach(token => {
      // We discard <h1> title because according to http://keepachangelog.com/en/1.0.0,
      // there should be only one of these and it's the main title.
      if (token.type !== 'heading_open' || token.tag === 'h1') {
        return;
      }

      const indexInBreadcrumbs = Number(token.tag.substring(1)) - 2;
      const indexOfTitleToken = tokens.indexOf(token) + 1;
      const titleToken = tokens[indexOfTitleToken];
      const title =
        indexInBreadcrumbs === 0
          ? // <h2> titles are release titles.
            // We only keep the release name and discard the release date.
            titleToken.content.match(/\[([^\\]+)\]/)[1]
          : titleToken.content;

      breadcrumbs.length = indexInBreadcrumbs;
      breadcrumbs[indexInBreadcrumbs] = title;

      const slug = getSlug(breadcrumbs);
      const linkOpenToken = new Token('link_open', 'a', 1);
      linkOpenToken.attrSet('class', 'anchor');
      linkOpenToken.attrSet('href', `#${slug}`);
      linkOpenToken.attrSet('id', slug);

      const permalinkToken = new Token('html_inline', '', 0);
      permalinkToken.content = permalinkIcon;

      replacements.push({
        replacementTokens: [
          linkOpenToken,
          permalinkToken,
          new Token('link_close', 'a', -1),
          titleToken,
        ],
        tokenToReplace: titleToken,
      });
    });

    replacements.forEach(replaceTokenWithOthers);
  });
};

module.exports = {markdownItChangelogPlugin};