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   1  <?php
   2  /**
   3   * Custom CSS block support.
   4   *
   5   * @package WordPress
   6   */
   7  
   8  /**
   9   * Render the custom CSS stylesheet and add class name to block as required.
  10   *
  11   * @since 7.0.0
  12   *
  13   * @param array $parsed_block The parsed block.
  14   * @return array The same parsed block with custom CSS class name added if appropriate.
  15   *
  16   * @phpstan-param array{
  17   *     blockName: string|null,
  18   *     attrs: array{
  19   *         className?: string,
  20   *         style?: array{
  21   *             css?: string,
  22   *             ...
  23   *         },
  24   *         ...
  25   *     },
  26   *     ...
  27   * } $parsed_block
  28   */
  29  function wp_render_custom_css_support_styles( $parsed_block ) {
  30      $custom_css = $parsed_block['attrs']['style']['css'] ?? null;
  31      if ( ! is_string( $custom_css ) || '' === trim( $custom_css ) ) {
  32          return $parsed_block;
  33      }
  34  
  35      $block_type = WP_Block_Type_Registry::get_instance()->get_registered( $parsed_block['blockName'] );
  36      if ( ! block_has_support( $block_type, 'customCSS', true ) ) {
  37          return $parsed_block;
  38      }
  39  
  40      // Validate CSS doesn't contain HTML markup (same validation as global styles REST API).
  41      if ( preg_match( '#</?\w+#', $custom_css ) ) {
  42          return $parsed_block;
  43      }
  44  
  45      // Generate a unique class name for this block instance.
  46      $class_name          = wp_unique_id_from_values( $parsed_block, 'wp-custom-css-' );
  47      $existing_class_name = $parsed_block['attrs']['className'] ?? null;
  48      $updated_class_name  = is_string( $existing_class_name )
  49          ? "$existing_class_name $class_name"
  50          : $class_name;
  51  
  52      _wp_array_set( $parsed_block, array( 'attrs', 'className' ), $updated_class_name );
  53  
  54      // Process the custom CSS using the same method as global styles.
  55      $selector      = '.' . $class_name;
  56      $processed_css = WP_Theme_JSON::process_blocks_custom_css( $custom_css, $selector );
  57  
  58      if ( ! empty( $processed_css ) ) {
  59          /*
  60           * Register and add inline style for block custom CSS.
  61           * The style depends on global-styles to ensure custom CSS loads after
  62           * and can override global styles.
  63           */
  64          wp_register_style( 'wp-block-custom-css', false, array( 'global-styles' ) );
  65          wp_add_inline_style( 'wp-block-custom-css', $processed_css );
  66      }
  67  
  68      return $parsed_block;
  69  }
  70  
  71  /**
  72   * Enqueues the block custom CSS styles.
  73   *
  74   * @since 7.0.0
  75   */
  76  function wp_enqueue_block_custom_css() {
  77      wp_enqueue_style( 'wp-block-custom-css' );
  78  }
  79  
  80  /**
  81   * Applies the custom CSS class name to the block's rendered HTML.
  82   *
  83   * The class name is generated in {@see wp_render_custom_css_support_styles()}
  84   * and stored in block attributes. This filter adds it to the actual markup.
  85   *
  86   * @since 7.0.0
  87   *
  88   * @param string $block_content Rendered block content.
  89   * @param array  $block         Block object.
  90   * @return string               Filtered block content.
  91   *
  92   * @phpstan-param array{
  93   *     attrs: array{
  94   *         className?: string,
  95   *         ...
  96   *     },
  97   *     ...
  98   * } $block
  99   */
 100  function wp_render_custom_css_class_name( $block_content, $block ) {
 101      $class_name_attr   = $block['attrs']['className'] ?? null;
 102      $class_name_prefix = 'wp-custom-css-';
 103      if ( ! is_string( $class_name_attr ) || ! str_contains( $class_name_attr, $class_name_prefix ) ) {
 104          return $block_content;
 105      }
 106  
 107      // Parse out the 'wp-custom-css-*' class name added by wp_render_custom_css_support_styles().
 108      $matched_class_name = null;
 109      $token_delimiter    = " \t\f\r\n";
 110      $class_token        = strtok( $class_name_attr, $token_delimiter );
 111      while ( false !== $class_token ) {
 112          if ( str_starts_with( $class_token, $class_name_prefix ) ) {
 113              $matched_class_name = $class_token;
 114              break;
 115          }
 116          $class_token = strtok( $token_delimiter );
 117      }
 118      if ( null === $matched_class_name ) {
 119          return $block_content;
 120      }
 121  
 122      $tags = new WP_HTML_Tag_Processor( $block_content );
 123      if ( $tags->next_tag() ) {
 124          $tags->add_class( 'has-custom-css' );
 125          $tags->add_class( $matched_class_name );
 126      }
 127  
 128      return $tags->get_updated_html();
 129  }
 130  
 131  add_filter( 'render_block', 'wp_render_custom_css_class_name', 10, 2 );
 132  add_filter( 'render_block_data', 'wp_render_custom_css_support_styles', 10, 1 );
 133  add_action( 'wp_enqueue_scripts', 'wp_enqueue_block_custom_css', 1 );
 134  
 135  /**
 136   * Registers the style block attribute for block types that support it.
 137   *
 138   * @param WP_Block_Type $block_type Block Type.
 139   */
 140  function wp_register_custom_css_support( $block_type ) {
 141      // Setup attributes and styles within that if needed.
 142      if ( ! $block_type->attributes ) {
 143          $block_type->attributes = array();
 144      }
 145  
 146      // Check for existing style attribute definition e.g. from block.json.
 147      if ( array_key_exists( 'style', $block_type->attributes ) ) {
 148          return;
 149      }
 150  
 151      $has_custom_css_support = block_has_support( $block_type, array( 'customCSS' ), true );
 152  
 153      if ( $has_custom_css_support ) {
 154          $block_type->attributes['style'] = array(
 155              'type' => 'object',
 156          );
 157      }
 158  }
 159  
 160  /**
 161   * Strips custom CSS (`style.css` in attributes) from all blocks in post content.
 162   *
 163   * Uses {@see WP_Block_Parser::next_token()} to scan block tokens and surgically
 164   * replace only the attribute JSON that changed — no parse_blocks() +
 165   * serialize_blocks() round-trip needed.
 166   *
 167   * @since 7.0.0
 168   * @access private
 169   *
 170   * @param string $content Post content to filter, expected to be escaped with slashes.
 171   * @return string Filtered post content with block custom CSS removed.
 172   */
 173  function wp_strip_custom_css_from_blocks( $content ) {
 174      if ( ! has_blocks( $content ) ) {
 175          return $content;
 176      }
 177  
 178      $unslashed = stripslashes( $content );
 179  
 180      $parser           = new WP_Block_Parser();
 181      $parser->document = $unslashed;
 182      $parser->offset   = 0;
 183      $end              = strlen( $unslashed );
 184      $replacements     = array();
 185  
 186      while ( $parser->offset < $end ) {
 187          $next_token = $parser->next_token();
 188  
 189          if ( 'no-more-tokens' === $next_token[0] ) {
 190              break;
 191          }
 192  
 193          list( $token_type, , $attrs, $start_offset, $token_length ) = $next_token;
 194  
 195          $parser->offset = $start_offset + $token_length;
 196  
 197          if ( 'block-opener' !== $token_type && 'void-block' !== $token_type ) {
 198              continue;
 199          }
 200  
 201          if ( ! isset( $attrs['style']['css'] ) ) {
 202              continue;
 203          }
 204  
 205          // Remove css and clean up empty style.
 206          unset( $attrs['style']['css'] );
 207          if ( empty( $attrs['style'] ) ) {
 208              unset( $attrs['style'] );
 209          }
 210  
 211          // Locate the JSON portion within the token.
 212          $token_string   = substr( $unslashed, $start_offset, $token_length );
 213          $json_rel_start = strcspn( $token_string, '{' );
 214          $json_rel_end   = strrpos( $token_string, '}' );
 215  
 216          $json_start  = $start_offset + $json_rel_start;
 217          $json_length = $json_rel_end - $json_rel_start + 1;
 218  
 219          // Re-encode attributes. If attrs is now empty, remove JSON and trailing space.
 220          if ( empty( $attrs ) ) {
 221              // Remove the trailing space after JSON.
 222              $replacements[] = array( $json_start, $json_length + 1, '' );
 223          } else {
 224              $replacements[] = array( $json_start, $json_length, serialize_block_attributes( $attrs ) );
 225          }
 226      }
 227  
 228      if ( empty( $replacements ) ) {
 229          return $content;
 230      }
 231  
 232      // Build the result by splicing replacements into the original string.
 233      $result = '';
 234      $was_at = 0;
 235  
 236      foreach ( $replacements as $replacement ) {
 237          list( $offset, $length, $new_json ) = $replacement;
 238          $result                            .= substr( $unslashed, $was_at, $offset - $was_at ) . $new_json;
 239          $was_at                             = $offset + $length;
 240      }
 241  
 242      if ( $was_at < $end ) {
 243          $result .= substr( $unslashed, $was_at );
 244      }
 245  
 246      return addslashes( $result );
 247  }
 248  
 249  /**
 250   * Adds the filters to strip custom CSS from block content on save.
 251   * Priority of 8 to run before wp_filter_global_styles_post (priority 9) and wp_filter_post_kses (priority 10).
 252   *
 253   * @since 7.0.0
 254   * @access private
 255   */
 256  function wp_custom_css_kses_init_filters() {
 257      add_filter( 'content_save_pre', 'wp_strip_custom_css_from_blocks', 8 );
 258      add_filter( 'content_filtered_save_pre', 'wp_strip_custom_css_from_blocks', 8 );
 259  }
 260  
 261  /**
 262   * Removes the filters that strip custom CSS from block content on save.
 263   * Priority of 8 to run before wp_filter_global_styles_post (priority 9) and wp_filter_post_kses (priority 10).
 264   *
 265   * @since 7.0.0
 266   * @access private
 267   */
 268  function wp_custom_css_remove_filters() {
 269      remove_filter( 'content_save_pre', 'wp_strip_custom_css_from_blocks', 8 );
 270      remove_filter( 'content_filtered_save_pre', 'wp_strip_custom_css_from_blocks', 8 );
 271  }
 272  
 273  /**
 274   * Registers the custom CSS content filters if the user does not have the edit_css capability.
 275   *
 276   * @since 7.0.0
 277   * @access private
 278   */
 279  function wp_custom_css_kses_init() {
 280      wp_custom_css_remove_filters();
 281      if ( ! current_user_can( 'edit_css' ) ) {
 282          wp_custom_css_kses_init_filters();
 283      }
 284  }
 285  
 286  /**
 287   * Initializes custom CSS content filters when imported data should be filtered.
 288   *
 289   * Runs at priority 999 on {@see 'force_filtered_html_on_import'} to ensure it
 290   * fires after general KSES initialization, independently of user capabilities.
 291   * If the input of the filter is true it means we are in an import situation and should
 292   * enable the custom CSS filters, independently of the user capabilities.
 293   *
 294   * @since 7.0.0
 295   * @access private
 296   *
 297   * @param mixed $arg Input argument of the filter.
 298   * @return mixed Input argument of the filter.
 299   */
 300  function wp_custom_css_force_filtered_html_on_import_filter( $arg ) {
 301      if ( $arg ) {
 302          wp_custom_css_kses_init_filters();
 303      }
 304      return $arg;
 305  }
 306  
 307  // Run before wp_filter_global_styles_post (priority 9) and wp_filter_post_kses (priority 10).
 308  add_action( 'init', 'wp_custom_css_kses_init', 20 );
 309  add_action( 'set_current_user', 'wp_custom_css_kses_init' );
 310  add_filter( 'force_filtered_html_on_import', 'wp_custom_css_force_filtered_html_on_import_filter', 999 );
 311  
 312  // Register the block support.
 313  WP_Block_Supports::get_instance()->register(
 314      'custom-css',
 315      array(
 316          'register_attribute' => 'wp_register_custom_css_support',
 317      )
 318  );