<?php

/**

 * Appending the wp-block-heading to before rendering the stored `core/heading` block contents.

 *

 * @package WordPress

 */

/**

 * Adds a wp-block-heading class to the heading block content.

 *

 * For example, the following block content:

 *  <h2 class="align-left">Hello World</h2>

 *

 * Would be transformed to:

 *  <h2 class="align-left wp-block-heading">Hello World</h2>

 *

 * @since 6.2.0

 *

 * @param array  $attributes Attributes of the block being rendered.

 * @param string $content Content of the block being rendered.

 *

 * @return string The content of the block being rendered.

 */

function block_core_heading_render( $attributes, $content ) {

	if ( ! $content ) {

		return $content;

	}

	$p = new WP_HTML_Tag_Processor( $content );

	$header_tags = array( 'H1', 'H2', 'H3', 'H4', 'H5', 'H6' );

	while ( $p->next_tag() ) {

		if ( in_array( $p->get_tag(), $header_tags, true ) ) {

			$p->add_class( 'wp-block-heading' );

			break;

		}

	}

	return $p->get_updated_html();

}

/**

 * Registers the `core/heading` block on server.

 *

 * @since 6.2.0

 */

function register_block_core_heading() {

	register_block_type_from_metadata(

		__DIR__ . '/heading',

		array(

			'render_callback' => 'block_core_heading_render',

		)

	);

}

add_action( 'init', 'register_block_core_heading' );