<?php
/**
* Block support to enable per-section styling of block types via
* block style variations.
*
* @package WordPress
* @since 6.6.0
*/

/**
* Determines the block style variation names within a CSS class string.
*
* @since 6.6.0
*
* @param string $class_string CSS class string to look for a variation in.
*
* @return array|null The block style variation name if found.
*/
function wp_get_block_style_variation_name_from_class( $class_string ) {
if ( ! is_string( $class_string ) ) {
return null;
}

preg_match_all( '/\bis-style-(?!default)(\S+)\b/', $class_string, $matches );
return $matches[1] ?? null;
}

/**
* Recursively resolves any `ref` values within a block style variation's data.
*
* @since 6.6.0
* @access private
*
* @param array $variation_data Reference to the variation data being processed.
* @param array $theme_json Theme.json data to retrieve referenced values from.
*/
function wp_resolve_block_style_variation_ref_values( &$variation_data, $theme_json ) {
foreach ( $variation_data as $key => &$value ) {
// Only need to potentially process arrays.
if ( is_array( $value ) ) {
// If ref value is set, attempt to find its matching value and update it.
if ( array_key_exists( 'ref', $value ) ) {
// Clean up any invalid ref value.
if ( empty( $value['ref'] ) || ! is_string( $value['ref'] ) ) {
unset( $variation_data[ $key ] );
}

$value_path = explode( '.', $value['ref'] ?? '' );
$ref_value = _wp_array_get( $theme_json, $value_path );

// Only update the current value if the referenced path matched a value.
if ( null === $ref_value ) {
unset( $variation_data[ $key ] );
} else {
$value = $ref_value;
}
} else {
// Recursively look for ref instances.
wp_resolve_block_style_variation_ref_values( $value, $theme_json );
}
}
}
}
/**
* Renders the block style variation's styles.
*
* In the case of nested blocks with variations applied, we want the parent
* variation's styles to be rendered before their descendants. This solves the
* issue of a block type being styled in both the parent and descendant: we want
* the descendant style to take priority, and this is done by loading it after,
* in the DOM order. This is why the variation stylesheet generation is in a
* different filter.
*
* @since 6.6.0
* @access private
*
* @param array $parsed_block The parsed block.
*
* @return array The parsed block with block style variation classname added.
*/
function wp_render_block_style_variation_support_styles( $parsed_block ) {
$classes = $parsed_block['attrs']['className'] ?? null;
$variations = wp_get_block_style_variation_name_from_class( $classes );

if ( ! $variations ) {
return $parsed_block;
}

$tree = WP_Theme_JSON_Resolver::get_merged_data();
$theme_json = $tree->get_raw_data();

// Only the first block style variation with data is supported.
$variation_data = array();
foreach ( $variations as $variation ) {
$variation_data = $theme_json['styles']['blocks'][ $parsed_block['blockName'] ]['variations'][ $variation ] ?? array();

if ( ! empty( $variation_data ) ) {
break;
}
}

if ( empty( $variation_data ) ) {
return $parsed_block;
}

/*
* Recursively resolve any ref values with the appropriate value within the
* theme_json data.
*/
wp_resolve_block_style_variation_ref_values( $variation_data, $theme_json );

$variation_instance = wp_unique_id( $variation . '--' );
$class_name = "is-style-$variation_instance";
$updated_class_name = $parsed_block['attrs']['className'] . " $class_name";

/*
* Even though block style variations are effectively theme.json partials,
* they can't be processed completely as though they are.
*
* Block styles support custom selectors to direct specific types of styles
* to inner elements. For example, borders on Image block's get applied to
* the inner `img` element rather than the wrapping `figure`.
*
* The following relocates the "root" block style variation styles to
* under an appropriate blocks property to leverage the preexisting style
* generation for simple block style variations. This way they get the
* custom selectors they need.
*
* The inner elements and block styles for the variation itself are
* still included at the top level but scoped by the variation's selector
* when the stylesheet is generated.
*/
$elements_data = $variation_data['elements'] ?? array();
$blocks_data = $variation_data['blocks'] ?? array();
unset( $variation_data['elements'] );
unset( $variation_data['blocks'] );

_wp_array_set(
$blocks_data,
array( $parsed_block['blockName'], 'variations', $variation_instance ),
$variation_data
);

$config = array(
'version' => WP_Theme_JSON::LATEST_SCHEMA,
'styles' => array(
'elements' => $elements_data,
'blocks' => $blocks_data,
),
);

// Turn off filter that excludes block nodes. They are needed here for the variation's inner block types.
if ( ! is_admin() ) {
remove_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );
}

// Temporarily prevent variation instance from being sanitized while processing theme.json.
$styles_registry = WP_Block_Styles_Registry::get_instance();
$styles_registry->register( $parsed_block['blockName'], array( 'name' => $variation_instance ) );

$variation_theme_json = new WP_Theme_JSON( $config, 'blocks' );
$variation_styles = $variation_theme_json->get_stylesheet(
array( 'styles' ),
array( 'custom' ),
array(
'include_block_style_variations' => true,
'skip_root_layout_styles' => true,
'scope' => ".$class_name",
)
);

// Clean up temporary block style now instance styles have been processed.
$styles_registry->unregister( $parsed_block['blockName'], $variation_instance );

// Restore filter that excludes block nodes.
if ( ! is_admin() ) {
add_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );
}

if ( empty( $variation_styles ) ) {
return $parsed_block;
}

wp_register_style( 'block-style-variation-styles', false, array( 'wp-block-library', 'global-styles' ) );
wp_add_inline_style( 'block-style-variation-styles', $variation_styles );

/*
* Add variation instance class name to block's className string so it can
* be enforced in the block markup via render_block filter.
*/
_wp_array_set( $parsed_block, array( 'attrs', 'className' ), $updated_class_name );

return $parsed_block;
}

/**
* Ensures the variation block support class name generated and added to
* block attributes in the `render_block_data` filter gets applied to the
* block's markup.
*
* @since 6.6.0
* @access private
*
* @see wp_render_block_style_variation_support_styles
*
* @param string $block_content Rendered block content.
* @param array $block Block object.
*
* @return string Filtered block content.
*/
function wp_render_block_style_variation_class_name( $block_content, $block ) {
if ( ! $block_content || empty( $block['attrs']['className'] ) ) {
return $block_content;
}

/*
* Matches a class prefixed by `is-style`, followed by the
* variation slug, then `--`, and finally an instance number.
*/
preg_match( '/\bis-style-(\S+?--\d+)\b/', $block['attrs']['className'], $matches );

if ( empty( $matches ) ) {
return $block_content;
}

$tags = new WP_HTML_Tag_Processor( $block_content );

if ( $tags->next_tag() ) {
/*
* Ensure the variation instance class name set in the
* `render_block_data` filter is applied in markup.
* See `wp_render_block_style_variation_support_styles`.
*/
$tags->add_class( $matches[0] );
}

return $tags->get_updated_html();
}

/**
* Enqueues styles for block style variations.
*
* @since 6.6.0
* @access private
*/
function wp_enqueue_block_style_variation_styles() {
wp_enqueue_style( 'block-style-variation-styles' );
}

// Register the block support.
WP_Block_Supports::get_instance()->register( 'block-style-variation', array() );

add_filter( 'render_block_data', 'wp_render_block_style_variation_support_styles', 10, 2 );
add_filter( 'render_block', 'wp_render_block_style_variation_class_name', 10, 2 );
add_action( 'wp_enqueue_scripts', 'wp_enqueue_block_style_variation_styles', 1 );

/**
* Registers block style variations read in from theme.json partials.
*
* @since 6.6.0
* @access private
*
* @param array $variations Shared block style variations.
*/
function wp_register_block_style_variations_from_theme_json_partials( $variations ) {
if ( empty( $variations ) ) {
return;
}

$registry = WP_Block_Styles_Registry::get_instance();

foreach ( $variations as $variation ) {
if ( empty( $variation['blockTypes'] ) || empty( $variation['styles'] ) ) {
continue;
}

$variation_name = $variation['slug'] ?? _wp_to_kebab_case( $variation['title'] );
$variation_label = $variation['title'] ?? $variation_name;

foreach ( $variation['blockTypes'] as $block_type ) {
$registered_styles = $registry->get_registered_styles_for_block( $block_type );

// Register block style variation if it hasn't already been registered.
if ( ! array_key_exists( $variation_name, $registered_styles ) ) {
register_block_style(
$block_type,
array(
'name' => $variation_name,
'label' => $variation_label,
)
);
}
}
}
}