import { visit } from 'unist-util-visit';

const HEADING_CLASSES = ['alpha', 'beta', 'gamma', 'delta'];

/*

* Adds classes to headings and other content elements. For example, `<h2>` becomes

* `<h2 class="beta">. Many HTML elements should have default styles applied to them

* when used in a documentation article. However, there may be cases where those

* we don’t need the default styles, e.g. when using a list for a horizontal navigation.

* Applying the default styles explicitly using classes is easier and has fewer side

* effects compared to applying them using tag selectors (in which case they'd need to

* be reset manually whenever the default styles are not needed).

*/

export default function defaultClasses() {

return () => {

return (tree) => {

visit(tree, ['heading', 'list'], (node) => {

node.data = node.data || {};

node.data.hProperties = node.data.hProperties || {};

if (node.type === 'heading') {

node.data.hProperties = {

...node.data.hProperties,

class: HEADING_CLASSES[node.depth - 1],

};

return;

}

if (node.type === 'list') {

node.data.hProperties = {

...node.data.hProperties,

class: node.ordered ? 'ordered-list' : 'unordered-list',

};

return;

}

});

};

};

}