Support @-moz-document url-prefix() Firefox CSS hack by transforming into @supports (-moz-appearance:meterbar) (#5530)

Co-authored-by: Pierre Gordon <[email protected]>

Author: westonruter

includes/sanitizers/class-amp-core-theme-sanitizer.php

@@ -130,7 +130,6 @@ protected static function get_theme_features_config( $theme_slug ) {
 					],
 					'add_twentynineteen_masthead_styles' => [],
 					'adjust_twentynineteen_images'       => [],
-					'accept_remove_moz_document_at_rule' => [],
 				];
 
 			// Twenty Seventeen.
@@ -289,27 +288,6 @@ public static function get_acceptable_errors() {
 		return [];
 	}
 
-	/**
-	 * Accept the removal of `@-moz-document` at-rules.
-	 *
-	 * This is temporary with the hope that the at-rule will become allowed in AMP.
-	 *
-	 * @since 2.0.1
-	 * @link https://github.com/ampproject/amp-wp/issues/5302
-	 * @link https://github.com/ampproject/amphtml/issues/26406
-	 */
-	public static function accept_remove_moz_document_at_rule() {
-		AMP_Validation_Error_Taxonomy::accept_validation_errors(
-			[
-				AMP_Style_Sanitizer::CSS_SYNTAX_INVALID_AT_RULE => [
-					[
-						'at_rule' => '-moz-document',
-					],
-				],
-			]
-		);
-	}
-
 	/**
 	 * Adds extra theme support arguments on the fly.
 	 *

includes/sanitizers/class-amp-style-sanitizer.php

@@ -381,15 +381,6 @@ public static function get_css_parser_validation_error_codes() {
 	 * @return bool Returns true if the plugin's forked version of PHP-CSS-Parser is loaded by Composer.
 	 */
 	public static function has_required_php_css_parser() {
-		$has_required_methods = (
-			method_exists( 'Sabberworm\CSS\CSSList\Document', 'splice' )
-			&&
-			method_exists( 'Sabberworm\CSS\CSSList\Document', 'replace' )
-		);
-		if ( ! $has_required_methods ) {
-			return false;
-		}
-
 		$reflection = new ReflectionClass( 'Sabberworm\CSS\OutputFormat' );
 
 		$has_output_format_extensions = (
@@ -1570,7 +1561,7 @@ private function get_parsed_stylesheet( $stylesheet, $options = [] ) {
 		$parsed         = null;
 		$cache_key      = null;
 		$cached         = true;
-		$cache_group    = 'amp-parsed-stylesheet-v33'; // This should be bumped whenever the PHP-CSS-Parser is updated or parsed format is updated.
+		$cache_group    = 'amp-parsed-stylesheet-v34'; // This should be bumped whenever the PHP-CSS-Parser is updated or parsed format is updated.
 		$use_transients = $this->should_use_transient_caching();
 
 		$cache_impacting_options = array_merge(
@@ -1743,25 +1734,48 @@ private function splice_imported_stylesheet( Import $item, CSSList $css_list, $o
 		);
 		$viewport_rules     = $parsed_stylesheet['viewport_rules'];
 
-		if ( ! empty( $parsed_stylesheet['css_document'] ) && method_exists( $css_list, 'replace' ) ) {
+		if ( ! empty( $parsed_stylesheet['css_document'] ) ) {
 			/**
 			 * CSS Doc.
 			 *
 			 * @var CSSDocument $css_document
 			 */
 			$css_document = $parsed_stylesheet['css_document'];
 
-			// Work around bug in \Sabberworm\CSS\CSSList\CSSList::replace() when array keys are not 0-based.
-			$css_list->setContents( array_values( $css_list->getContents() ) );
-
-			$css_list->replace( $item, $css_document->getContents() );
+			$this->replace_inside_css_list( $css_list, $item, $css_document->getContents() );
 		} else {
 			$css_list->remove( $item );
 		}
 
 		return compact( 'validation_results', 'imported_font_urls', 'viewport_rules' );
 	}
 
+	/**
+	 * Replace an item inside of a CSSList.
+	 *
+	 * This is being used instead of `CSSList::splice()` because it uses `array_splice()` which does not work properly
+	 * if the array keys are not sequentially indexed from 0, which happens when `CSSList::remove()` is employed.
+	 *
+	 * @see CSSList::splice()
+	 * @see CSSList::replace()
+	 * @see CSSList::remove()
+	 *
+	 * @param CSSList                      $css_list  CSS list.
+	 * @param AtRule|RuleSet|CSSList       $old_item  Old item.
+	 * @param AtRule[]|RuleSet[]|CSSList[] $new_items New item(s). If empty, the old item is simply removed.
+	 * @return bool Whether the replacement was successful.
+	 */
+	private function replace_inside_css_list( CSSList $css_list, $old_item, $new_items = [] ) {
+		$contents = array_values( $css_list->getContents() ); // Required to obtain the offset instead of the index.
+		$offset   = array_search( $old_item, $contents, true );
+		if ( false !== $offset ) {
+			array_splice( $contents, $offset, 1, $new_items );
+			$css_list->setContents( $contents );
+			return true;
+		}
+		return false;
+	}
+
 	/**
 	 * Create validated CSS document.
 	 *
@@ -2138,7 +2152,24 @@ private function process_css_list( CSSList $css_list, $options ) {
 					$this->process_css_declaration_block( $css_item, $css_list, $options )
 				);
 			} elseif ( $css_item instanceof AtRuleBlockList ) {
-				if ( ! in_array( $css_item->atRuleName(), $options['allowed_at_rules'], true ) ) {
+				if (
+					'-moz-document' === $css_item->atRuleName()
+					&&
+					'url-prefix()' === $css_item->atRuleArgs()
+					&&
+					in_array( 'supports', $options['allowed_at_rules'], true )
+				) {
+					// Replace `@-moz-document url-prefix()` with `@supports (-moz-appearance:meterbar)` as an alternative
+					// way to provide Firefox-specific style rules. This is a workaround since @-moz-document is not
+					// yet allowed in AMP, and this use of @supports is another recognized Firefox-specific CSS hack,
+					// per <http://browserhacks.com/#hack-8e9b5504d9fda44ec75169381b3c3157>.
+					// For adding @-moz-document to AMP, see <https://github.com/ampproject/amphtml/issues/26406>.
+					$new_css_item = new AtRuleBlockList( 'supports', '(-moz-appearance:meterbar)' );
+					$new_css_item->setContents( $css_item->getContents() );
+					$this->replace_inside_css_list( $css_list, $css_item, [ $new_css_item ] );
+					$css_item  = $new_css_item; // To process_css_list below.
+					$sanitized = false;
+				} elseif ( ! in_array( $css_item->atRuleName(), $options['allowed_at_rules'], true ) ) {
 					$error                = [
 						'code'      => self::CSS_SYNTAX_INVALID_AT_RULE,
 						'at_rule'   => $css_item->atRuleName(),
@@ -2702,13 +2733,12 @@ static function( Selector $old_selector ) {
 		);
 		$important_ruleset->setRules( $importants );
 
-		$i = array_search( $ruleset, $css_list->getContents(), true );
-		if ( false !== $i && method_exists( $css_list, 'splice' ) ) {
-			$css_list->splice( $i + 1, 0, [ $important_ruleset ] );
-		} else {
-			$css_list->append( $important_ruleset );
+		$contents = array_values( $css_list->getContents() ); // Ensure keys are 0-indexed and sequential.
+		$offset   = array_search( $ruleset, $contents, true );
+		if ( false !== $offset ) {
+			array_splice( $contents, $offset + 1, 0, [ $important_ruleset ] );
+			$css_list->setContents( $contents );
 		}
-
 		return $results;
 	}
 

src/PluginSuppression.php

@@ -45,6 +45,18 @@ final class PluginSuppression implements Service, Registerable {
 	 */
 	private $callback_reflection;
 
+	/**
+	 * Original render callbacks for blocks.
+	 *
+	 * Populated via the `register_block_type_args` filter at the moment the block is first registered. This is useful
+	 * to detect a suppressed plugin's blocks which had their `render_callback` wrapped by another function before
+	 * plugin suppression is started at the `wp` action.
+	 *
+	 * @see gutenberg_current_parsed_block_tracking()
+	 * @var array
+	 */
+	private $original_block_render_callbacks = [];
+
 	/**
 	 * Instantiate the plugin suppression service.
 	 *
@@ -63,6 +75,18 @@ public function register() {
 		add_filter( 'amp_default_options', [ $this, 'filter_default_options' ] );
 		add_filter( 'amp_options_updating', [ $this, 'sanitize_options' ], 10, 2 );
 
+		add_filter(
+			'register_block_type_args',
+			function ( $props, $block_name ) {
+				if ( isset( $props['render_callback'] ) ) {
+					$this->original_block_render_callbacks[ $block_name ] = $props['render_callback'];
+				}
+				return $props;
+			},
+			~PHP_INT_MAX,
+			2
+		);
+
 		// When a Reader theme is selected and an AMP request is being made, start suppressing as early as possible.
 		// This can be done because we know it is an AMP page due to the query parameter, but it also _has_ to be done
 		// specifically for the case of accessing the AMP Customizer (in which customize.php is requested with the query
@@ -426,11 +450,22 @@ private function suppress_blocks( $suppressed_plugins ) {
 		$registry = WP_Block_Type_Registry::get_instance();
 
 		foreach ( $registry->get_all_registered() as $block_type ) {
-			if ( ! $block_type->is_dynamic() || ! $this->is_callback_plugin_suppressed( $block_type->render_callback, $suppressed_plugins ) ) {
+			if ( ! $block_type->is_dynamic() ) {
 				continue;
 			}
-			unset( $block_type->script, $block_type->style );
-			$block_type->render_callback = '__return_empty_string';
+
+			if (
+				$this->is_callback_plugin_suppressed( $block_type->render_callback, $suppressed_plugins )
+				||
+				(
+					isset( $this->original_block_render_callbacks[ $block_type->name ] )
+					&&
+					$this->is_callback_plugin_suppressed( $this->original_block_render_callbacks[ $block_type->name ], $suppressed_plugins )
+				)
+			) {
+				unset( $block_type->script, $block_type->style );
+				$block_type->render_callback = '__return_empty_string';
+			}
 		}
 	}