<?php
/**
* Server-side rendering of the `core/button` block.
*
* @package WordPress
*/

/**
* Renders the `core/button` block on the server,
*
* @since 6.6.0
*
* @param array $attributes The block attributes.
* @param string $content The block content.
* @param WP_Block $block The block object.
*
* @return string The block content.
*/
function render_block_core_button( $attributes, $content ) {
$p = new WP_HTML_Tag_Processor( $content );

/*
* The button block can render an `<a>` or `<button>` and also has a
* `<div>` wrapper. Find the a or button tag.
*/
$tag = null;
while ( $p->next_tag() ) {
$tag = $p->get_tag();
if ( 'A' === $tag || 'BUTTON' === $tag ) {
break;
}
}

/*
* If this happens, the likelihood is there's no block content,
* or the block has been modified by a plugin.
*/
if ( null === $tag ) {
return $content;
}

// If the next token is the closing tag, the button is empty.
$is_empty = true;
while ( $p->next_token() && $tag !== $p->get_token_name() && $is_empty ) {
if ( '#comment' !== $p->get_token_type() ) {
/**
* Anything else implies this is not empty.
* This might include any text content (including a space),
* inline images or other HTML.
*/
$is_empty = false;
}
}

/*
* When there's no text, render nothing for the block.
* See https://github.com/WordPress/gutenberg/issues/17221 for the
* reasoning behind this.
*/
if ( $is_empty ) {
return '';
}

return $content;
}

/**
* Registers the `core/button` block on server.
*
* @since 6.6.0
*/
function register_block_core_button() {
register_block_type_from_metadata(
__DIR__ . '/button',
array(
'render_callback' => 'render_block_core_button',
)
);
}
add_action( 'init', 'register_block_core_button' );