add wp-rocket

wp-content/plugins/wp-rocket/inc/Engine/Optimization/Minify/CSS/AbstractCSSOptimization.php

@@ -0,0 +1,148 @@
+<?php
+
+namespace WP_Rocket\Engine\Optimization\Minify\CSS;
+
+use WP_Rocket\Admin\Options_Data;
+use WP_Rocket\Engine\Optimization\AbstractOptimization;
+use WP_Rocket\Engine\Optimization\AssetsLocalCache;
+
+/**
+ * Abstract class for CSS Optimization
+ *
+ * @since  3.1
+ */
+abstract class AbstractCSSOptimization extends AbstractOptimization {
+	const FILE_TYPE = 'css';
+
+	/**
+	 * Assets local cache instance
+	 *
+	 * @var AssetsLocalCache
+	 */
+	protected $local_cache;
+
+	/**
+	 * Creates an instance of inheriting class.
+	 *
+	 * @since  3.1
+	 *
+	 * @param Options_Data     $options     Options instance.
+	 * @param AssetsLocalCache $local_cache AssetsLocalCache instance.
+	 */
+	public function __construct( Options_Data $options, AssetsLocalCache $local_cache ) {
+		$this->options        = $options;
+		$this->local_cache    = $local_cache;
+		$this->minify_key     = $this->options->get( 'minify_css_key', create_rocket_uniqid() );
+		$this->excluded_files = $this->get_excluded_files();
+		$this->init_base_path_and_url();
+	}
+
+	/**
+	 * Get all files to exclude from minification/concatenation.
+	 *
+	 * @since  2.11
+	 *
+	 * @return string
+	 */
+	protected function get_excluded_files() {
+		$excluded_files = $this->options->get( 'exclude_css', [] );
+
+		/**
+		 * Filters CSS files to exclude from minification/concatenation.
+		 *
+		 * @since 2.6
+		 *
+		 * @param array $excluded_files List of excluded CSS files.
+		 */
+		$excluded_files = (array) apply_filters( 'rocket_exclude_css', $excluded_files );
+
+		if ( empty( $excluded_files ) ) {
+			return '';
+		}
+
+		foreach ( $excluded_files as $i => $excluded_file ) {
+			$excluded_files[ $i ] = str_replace( '#', '\#', $excluded_file );
+		}
+
+		return implode( '|', $excluded_files );
+	}
+
+	/**
+	 * Returns the CDN zones.
+	 *
+	 * @since  3.1
+	 *
+	 * @return array
+	 */
+	public function get_zones() {
+		return [ 'all', 'css_and_js', self::FILE_TYPE ];
+	}
+
+	/**
+	 * Gets the minify URL
+	 *
+	 * @since  3.1
+	 *
+	 * @param string $filename     Minified filename.
+	 * @param string $original_url Original URL for this file. Optional.
+	 *
+	 * @return string
+	 */
+	protected function get_minify_url( $filename, $original_url = '' ) {
+		$minify_url = $this->minify_base_url . $filename;
+
+		/**
+		 * Filters CSS file URL with CDN hostname
+		 *
+		 * @since 2.1
+		 *
+		 * @param string $minify_url   Minified file URL.
+		 * @param string $original_url Original URL for this file.
+		 */
+		return apply_filters( 'rocket_css_url', $minify_url, $original_url );
+	}
+
+	/**
+	 * Determines if it is a file excluded from minification
+	 *
+	 * @since  2.11
+	 *
+	 * @param array $tag Tag corresponding to a CSS file.
+	 *
+	 * @return bool True if it is a file excluded, false otherwise
+	 */
+	protected function is_minify_excluded_file( array $tag ) {
+		if ( ! isset( $tag[0], $tag['url'] ) ) {
+			return true;
+		}
+
+		// File should not be minified.
+		if ( false !== strpos( $tag[0], 'data-minify=' ) || false !== strpos( $tag[0], 'data-no-minify=' ) ) {
+			return true;
+		}
+
+		if ( false !== strpos( $tag[0], 'media=' ) && ! preg_match( '/media=["\'](?:\s*|[^"\']*?\b(all|screen)\b[^"\']*?)["\']/i', $tag[0] ) ) {
+			return true;
+		}
+
+		if ( false !== strpos( $tag[0], 'only screen and' ) ) {
+			return true;
+		}
+
+		$file_path = wp_parse_url( $tag['url'], PHP_URL_PATH );
+
+		// File extension is not css.
+		if ( pathinfo( $file_path, PATHINFO_EXTENSION ) !== self::FILE_TYPE ) {
+			return true;
+		}
+
+		if ( ! empty( $this->excluded_files ) ) {
+			// File is excluded from minification/concatenation.
+			if ( preg_match( '#^(' . $this->excluded_files . ')$#', $file_path ) ) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+}

wp-content/plugins/wp-rocket/inc/Engine/Optimization/Minify/CSS/AdminSubscriber.php

@@ -0,0 +1,125 @@
+<?php
+
+namespace WP_Rocket\Engine\Optimization\Minify\CSS;
+
+use WP_Rocket\Event_Management\Subscriber_Interface;
+
+/**
+ * Minify/Combine CSS Admin subscriber
+ *
+ * @since 3.5.4
+ */
+class AdminSubscriber implements Subscriber_Interface {
+	/**
+	 * Return an array of events that this subscriber wants to listen to.
+	 *
+	 * @since 3.5.4
+	 *
+	 * @return array
+	 */
+	public static function get_subscribed_events() {
+		$slug = rocket_get_constant( 'WP_ROCKET_SLUG', 'wp_rocket_settings' );
+
+		return [
+			"update_option_{$slug}"     => [ 'clean_minify', 10, 2 ],
+			"pre_update_option_{$slug}" => [ 'regenerate_minify_css_key', 10, 2 ],
+		];
+	}
+
+	/**
+	 * Clean minify CSS files when options change.
+	 *
+	 * @since  3.5.4
+	 *
+	 * @param array $old An array of previous settings.
+	 * @param array $new An array of submitted settings.
+	 */
+	public function clean_minify( $old, $new ) {
+		if ( ! is_array( $old ) || ! is_array( $new ) ) {
+			return;
+		}
+
+		if ( ! $this->maybe_minify_regenerate( $new, $old ) ) {
+			return;
+		}
+		// Purge all minify cache files.
+		rocket_clean_minify( 'css' );
+	}
+
+	/**
+	 * Regenerate the minify key if CSS files have been modified.
+	 *
+	 * @since  3.5.4
+	 *
+	 * @param array $new An array of submitted settings.
+	 * @param array $old An array of previous settings.
+	 *
+	 * @return array Updates 'minify_css_key' setting when regenerated; else, original submitted settings.
+	 */
+	public function regenerate_minify_css_key( $new, $old ) {
+		if ( ! is_array( $old ) || ! is_array( $new ) ) {
+			return $new;
+		}
+
+		if ( ! $this->maybe_minify_regenerate( $new, $old ) ) {
+			return $new;
+		}
+
+		$new['minify_css_key'] = create_rocket_uniqid();
+
+		return $new;
+	}
+
+	/**
+	 * Checks minify CSS condition when options change.
+	 *
+	 * @since  3.5.4
+	 *
+	 * @param array $new An array of submitted settings.
+	 * @param array $old An array of previous settings.
+	 *
+	 * @return bool true when should regenerate; else false.
+	 */
+	protected function maybe_minify_regenerate( array $new, array $old ) {
+		$settings_to_check = [
+			'minify_css',
+			'exclude_css',
+			'cdn',
+		];
+
+		foreach ( $settings_to_check as $setting ) {
+			if ( $this->did_setting_change( $setting, $new, $old ) ) {
+				return true;
+			}
+		}
+
+		return (
+			array_key_exists( 'cdn', $new )
+			&&
+			1 === (int) $new['cdn']
+			&&
+			$this->did_setting_change( 'cdn_cnames', $new, $old )
+		);
+	}
+
+	/**
+	 * Checks if the given setting's value changed.
+	 *
+	 * @since 3.5.4
+	 *
+	 * @param string $setting The settings's value to check in the old and new values.
+	 * @param array  $new     An array of submitted settings.
+	 * @param array  $old     An array of previous settings.
+	 *
+	 * @return bool
+	 */
+	protected function did_setting_change( $setting, array $new, array $old ) {
+		return (
+			array_key_exists( $setting, $old )
+			&&
+			array_key_exists( $setting, $new )
+			&&
+			$old[ $setting ] !== $new[ $setting ]
+		);
+	}
+}

wp-content/plugins/wp-rocket/inc/Engine/Optimization/Minify/CSS/Combine.php

@@ -0,0 +1,322 @@
+<?php
+namespace WP_Rocket\Engine\Optimization\Minify\CSS;
+
+use WP_Rocket\Dependencies\Minify\CSS as MinifyCSS;
+use WP_Rocket\Engine\Optimization\CSSTrait;
+use WP_Rocket\Engine\Optimization\Minify\ProcessorInterface;
+use WP_Rocket\Logger\Logger;
+
+/**
+ * Minify & Combine CSS files
+ *
+ * @since 3.1
+ */
+class Combine extends AbstractCSSOptimization implements ProcessorInterface {
+	use CSSTrait;
+
+	/**
+	 * Array of styles
+	 *
+	 * @var array
+	 */
+	private $styles = [];
+
+	/**
+	 * Combined CSS filename
+	 *
+	 * @var string
+	 */
+	private $filename;
+
+	/**
+	 * Minifies and combines all CSS files into one
+	 *
+	 * @since 3.1
+	 *
+	 * @param string $html HTML content.
+	 * @return string
+	 */
+	public function optimize( $html ) {
+		Logger::info( 'CSS COMBINE PROCESS STARTED.', [ 'css combine process' ] );
+
+		$html_nocomments = $this->hide_comments( $html );
+		$styles          = $this->find( '<link\s+([^>]+[\s"\'])?href\s*=\s*[\'"]\s*?(?<url>[^\'"]+\.css(?:\?[^\'"]*)?)\s*?[\'"]([^>]+)?\/?>', $html_nocomments );
+
+		if ( ! $styles ) {
+			Logger::debug( 'No `<link>` tags found.', [ 'css combine process' ] );
+			return $html;
+		}
+
+		Logger::debug(
+			'Found ' . count( $styles ) . ' `<link>` tag(s).',
+			[
+				'css combine process',
+				'tags' => $styles,
+			]
+		);
+
+		$styles = $this->parse( $styles );
+
+		if ( empty( $styles ) ) {
+			Logger::debug( 'No `<link>` tags to optimize.', [ 'css combine process' ] );
+			return $html;
+		}
+
+		Logger::debug(
+			count( $styles ) . ' `<link>` tag(s) remaining.',
+			[
+				'css combine process',
+				'tags' => $styles,
+			]
+		);
+
+		if ( ! $this->combine() ) {
+			Logger::error( 'CSS combine process failed.', [ 'css combine process' ] );
+			return $html;
+		}
+
+		return $this->insert_combined_css( $html );
+	}
+
+	/**
+	 * Parses all found styles tag to keep only the ones to combine
+	 *
+	 * @since 3.7
+	 *
+	 * @param array $styles Array of matched styles.
+	 * @return array
+	 */
+	private function parse( array $styles ) {
+		foreach ( $styles as $key => $style ) {
+			if ( $this->is_external_file( $style['url'] ) ) {
+				if ( $this->is_excluded_external( $style['url'] ) ) {
+					unset( $styles[ $key ] );
+
+					continue;
+				}
+
+				$this->styles[ $style['url'] ] = [
+					'type' => 'external',
+					'tag'  => $style[0],
+					'url'  => rocket_add_url_protocol( strtok( $style['url'], '?' ) ),
+				];
+
+				continue;
+			}
+
+			if ( $this->is_minify_excluded_file( $style ) ) {
+				Logger::debug(
+					'Style is excluded.',
+					[
+						'css combine process',
+						'tag' => $style[0],
+					]
+				);
+
+				unset( $styles[ $key ] );
+
+				continue;
+			}
+
+			$this->styles[ $style['url'] ] = [
+				'type' => 'internal',
+				'tag'  => $style[0],
+				'url'  => strtok( $style['url'], '?' ),
+			];
+		}
+
+		return $styles;
+	}
+
+	/**
+	 * Checks if the provided external URL is excluded from combine
+	 *
+	 * @since 3.7
+	 *
+	 * @param string $url External URL to check.
+	 * @return boolean
+	 */
+	private function is_excluded_external( $url ) {
+		foreach ( $this->get_excluded_externals() as $excluded ) {
+			if ( false !== strpos( $url, $excluded ) ) {
+				Logger::debug(
+					'Style is external.',
+					[
+						'css combine process',
+						'url' => $url,
+					]
+				);
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Gets external URLs excluded from combine
+	 *
+	 * @since 3.7
+	 *
+	 * @return array
+	 */
+	private function get_excluded_externals() {
+		/**
+		 * Filters CSS external URLs to exclude from the combine process
+		 *
+		 * @since 3.7
+		 *
+		 * @param array $pattern Patterns to match.
+		 */
+		$excluded_externals = (array) apply_filters( 'rocket_combine_css_excluded_external', [] );
+
+		return array_merge( $excluded_externals, $this->options->get( 'exclude_css', [] ) );
+	}
+
+	/**
+	 * Combine the CSS content into one file and save it
+	 *
+	 * @since 3.1
+	 *
+	 * @return bool True if successful, false otherwise
+	 */
+	protected function combine() {
+		if ( empty( $this->styles ) ) {
+			return false;
+		}
+
+		$file_hash      = implode( ',', array_column( $this->styles, 'url' ) );
+		$this->filename = md5( $file_hash . $this->minify_key ) . '.css';
+
+		$combined_file = $this->minify_base_path . $this->filename;
+
+		if ( rocket_direct_filesystem()->exists( $combined_file ) ) {
+			Logger::debug(
+				'Combined CSS file already exists.',
+				[
+					'css combine process',
+					'path' => $combined_file,
+				]
+			);
+
+			return true;
+		}
+
+		$combined_content = $this->get_content( $combined_file );
+		$combined_content = $this->apply_font_display_swap( $combined_content );
+
+		if ( empty( $combined_content ) ) {
+			Logger::error(
+				'No combined content.',
+				[
+					'css combine process',
+					'path' => $combined_file,
+				]
+			);
+			return false;
+		}
+
+		if ( ! $this->write_file( $combined_content, $combined_file ) ) {
+			Logger::error(
+				'Combined CSS file could not be created.',
+				[
+					'css combine process',
+					'path' => $combined_file,
+				]
+			);
+			return false;
+		}
+
+		Logger::debug(
+			'Combined CSS file successfully created.',
+			[
+				'css combine process',
+				'path' => $combined_file,
+			]
+		);
+
+		return true;
+	}
+
+	/**
+	 * Insert the combined CSS file and remove the original CSS tags
+	 *
+	 * The combined CSS file is added after the closing </title> tag, and the replacement occurs only once. The original CSS tags are then removed from the HTML.
+	 *
+	 * @since 3.3.3
+	 *
+	 * @param string $html HTML content.
+	 * @return string
+	 */
+	protected function insert_combined_css( $html ) {
+		foreach ( $this->styles as $style ) {
+			$html = str_replace( $style['tag'], '', $html );
+		}
+
+		$minify_url = $this->get_minify_url( $this->filename );
+
+		Logger::info(
+			'Combined CSS file successfully added.',
+			[
+				'css combine process',
+				'url' => $minify_url,
+			]
+		);
+
+		// phpcs:ignore WordPress.WP.EnqueuedResources.NonEnqueuedStylesheet
+		return preg_replace( '/<\/title>/i', '$0<link rel="stylesheet" href="' . esc_url( $minify_url ) . '" media="all" data-minify="1" />', $html, 1 );
+	}
+
+	/**
+	 * Gathers the content from all styles to combine & minify it if needed
+	 *
+	 * @since 3.7
+	 *
+	 * @param string $combined_file Absolute path to the combined file.
+	 * @return string
+	 */
+	private function get_content( $combined_file ) {
+		$content = '';
+
+		foreach ( $this->styles as $key => $style ) {
+			if ( 'internal' === $style['type'] ) {
+				$filepath     = $this->get_file_path( $style['url'] );
+				$file_content = $this->get_file_content( $filepath );
+				$file_content = $this->rewrite_paths( $filepath, $combined_file, $file_content );
+			} elseif ( 'external' === $style['type'] ) {
+				$file_content = $this->local_cache->get_content( $style['url'] );
+				$file_content = $this->rewrite_paths( $style['url'], $combined_file, $file_content );
+			}
+
+			if ( empty( $file_content ) ) {
+				unset( $this->styles[ $key ] );
+
+				continue;
+			}
+
+			$content .= $file_content;
+		}
+
+		$content = $this->minify( $content );
+
+		if ( empty( $content ) ) {
+			Logger::debug( 'No CSS content.', [ 'css combine process' ] );
+		}
+
+		return $content;
+	}
+
+	/**
+	 * Minifies the content
+	 *
+	 * @since 3.1
+	 *
+	 * @param string $content Content to minify.
+	 * @return string
+	 */
+	protected function minify( $content ) {
+		$minifier = new MinifyCSS( $content );
+
+		return $minifier->minify();
+	}
+}

wp-content/plugins/wp-rocket/inc/Engine/Optimization/Minify/CSS/Minify.php

@@ -0,0 +1,331 @@
+<?php
+namespace WP_Rocket\Engine\Optimization\Minify\CSS;
+
+use WP_Rocket\Dependencies\Minify as Minifier;
+use WP_Rocket\Engine\Optimization\CSSTrait;
+use WP_Rocket\Engine\Optimization\Minify\ProcessorInterface;
+use WP_Rocket\Logger\Logger;
+
+/**
+ * Minify CSS files
+ *
+ * @since 3.1
+ */
+class Minify extends AbstractCSSOptimization implements ProcessorInterface {
+	use CSSTrait;
+
+	/**
+	 * Minifies CSS files
+	 *
+	 * @since 3.1
+	 *
+	 * @param string $html HTML content.
+	 * @return string
+	 */
+	public function optimize( $html ) {
+		Logger::info( 'CSS MINIFICATION PROCESS STARTED.', [ 'css minification process' ] );
+
+		$styles = $this->get_styles( $html );
+
+		if ( empty( $styles ) ) {
+			return $html;
+		}
+
+		foreach ( $styles as $style ) {
+			if ( $this->is_minify_excluded_file( $style ) ) {
+				Logger::debug(
+					'Style is excluded.',
+					[
+						'css minification process',
+						'tag' => $style[0],
+					]
+				);
+
+				continue;
+			}
+
+			$integrity_validated = $this->local_cache->validate_integrity( $style );
+
+			if ( false === $integrity_validated ) {
+				Logger::debug(
+					'Style integrity attribute not valid.',
+					[
+						'css minification process',
+						'tag' => $style[0],
+					]
+				);
+
+				continue;
+			}
+
+			$style['final'] = $integrity_validated;
+
+			$minify_url = $this->replace_url( strtok( $style['url'], '?' ) );
+
+			if ( ! $minify_url ) {
+				Logger::error(
+					'Style minification failed.',
+					[
+						'css minification process',
+						'tag' => $style[0],
+					]
+				);
+				continue;
+			}
+
+			$html = $this->replace_style( $style, $minify_url, $html );
+		}
+
+		return $html;
+	}
+
+	/**
+	 * Get all style tags from HTML.
+	 *
+	 * @param  string $html HTML content.
+	 * @return array Array with style tags, empty array if no style tags found.
+	 */
+	protected function get_styles( $html ) {
+		$html_nocomments = $this->hide_comments( $html );
+		$styles          = $this->find( '<link\s+([^>]+[\s"\'])?href\s*=\s*[\'"]\s*?(?<url>[^\'"]+\.css(?:\?[^\'"]*)?)\s*?[\'"]([^>]+)?\/?>', $html_nocomments );
+
+		if ( ! $styles ) {
+			Logger::debug( 'No `<link>` tags found.', [ 'css minification process' ] );
+			return [];
+		}
+
+		Logger::debug(
+			'Found ' . count( $styles ) . ' `<link>` tags.',
+			[
+				'css minification process',
+				'tags' => $styles,
+			]
+		);
+
+		return $styles;
+	}
+
+	/**
+	 * Creates the minify URL if the minification is successful
+	 *
+	 * @since 2.11
+	 *
+	 * @param string $url Original file URL.
+
+	 * @return string|bool The minify URL if successful, false otherwise
+	 */
+	private function replace_url( $url ) {
+		if ( empty( $url ) ) {
+			return false;
+		}
+
+		// This filter is documented in /inc/classes/optimization/class-abstract-optimization.php.
+		$url = apply_filters( 'rocket_asset_url', $url, $this->get_zones() );
+
+		$parsed_url = wp_parse_url( $url );
+
+		if ( empty( $parsed_url['path'] ) ) {
+			return false;
+		}
+
+		if ( ! empty( $parsed_url['host'] ) ) {
+			$url = rocket_add_url_protocol( $url );
+		}
+
+		$unique_id     = md5( $url . $this->minify_key );
+		$filename      = preg_replace( '/\.(css)$/', '-' . $unique_id . '.css', ltrim( rocket_realpath( $parsed_url['path'] ), '/' ) );
+		$minified_file = rawurldecode( $this->minify_base_path . $filename );
+		$minify_url    = $this->get_minify_url( $filename, $url );
+
+		if ( rocket_direct_filesystem()->exists( $minified_file ) ) {
+			Logger::debug(
+				'Minified CSS file already exists.',
+				[
+					'css minification process',
+					'path' => $minified_file,
+				]
+			);
+			return $minify_url;
+		}
+
+		$external_url = $this->is_external_file( $url );
+		$file_path    = $external_url ? $this->local_cache->get_filepath( $url ) : $this->get_file_path( $url );
+
+		if ( empty( $file_path ) ) {
+			Logger::error(
+				'Couldn’t get the file path from the URL.',
+				[
+					'css minification process',
+					'url' => $url,
+				]
+			);
+			return false;
+		}
+
+		$file_content = $external_url ? $this->local_cache->get_content( $url ) : $this->get_file_content( $file_path );
+
+		if ( ! $file_content ) {
+			Logger::error(
+				'No file content.',
+				[
+					'css minification process',
+					'path' => $file_path,
+				]
+			);
+			return false;
+		}
+
+		$minified_content = $external_url ? $this->minify( $url, $minified_file, $file_content ) : $this->minify( $file_path, $minified_file, $file_content );
+
+		if ( empty( $minified_content ) ) {
+			return false;
+		}
+
+		$minified_content = $this->font_display_swap( $url, $minified_file, $minified_content );
+
+		if ( empty( $minified_content ) ) {
+			return false;
+		}
+
+		$save_minify_file = $this->save_minify_file( $minified_file, $minified_content );
+
+		if ( ! $save_minify_file ) {
+			return false;
+		}
+
+		return $minify_url;
+	}
+
+	/**
+	 * Replace old style tag with the minified tag.
+	 *
+	 * @param array  $style      Style matched data.
+	 * @param string $minify_url Minified URL.
+	 * @param string $html       HTML content.
+	 *
+	 * @return string
+	 */
+	protected function replace_style( $style, $minify_url, $html ) {
+		$replace_style = str_replace( $style['url'], $minify_url, $style['final'] );
+		$replace_style = str_replace( '<link', '<link data-minify="1"', $replace_style );
+		$html          = str_replace( $style[0], $replace_style, $html );
+
+		Logger::info(
+			'Style minification succeeded.',
+			[
+				'css minification process',
+				'url' => $minify_url,
+			]
+		);
+
+		return $html;
+	}
+
+	/**
+	 * Save minified CSS file.
+	 *
+	 * @since 3.7
+	 *
+	 * @param string $minified_file    Minified file path.
+	 * @param string $minified_content Minified HTML content.
+	 *
+	 * @return bool
+	 */
+	protected function save_minify_file( $minified_file, $minified_content ) {
+		$save_minify_file = $this->write_file( $minified_content, $minified_file );
+
+		if ( ! $save_minify_file ) {
+			Logger::error(
+				'Minified CSS file could not be created.',
+				[
+					'css minification process',
+					'path' => $minified_file,
+				]
+			);
+			return false;
+		}
+		Logger::debug(
+			'Minified CSS file successfully created.',
+			[
+				'css minification process',
+				'path' => $minified_file,
+			]
+		);
+		return true;
+	}
+
+	/**
+	 * Applies font display swap if the file contains @font-face.
+	 *
+	 * @since 3.7
+	 *
+	 * @param string $url           File Url.
+	 * @param string $minified_file Minified file path.
+	 * @param string $content       CSS file content.
+	 * @return string
+	 */
+	protected function font_display_swap( $url, $minified_file, $content ) {
+		if (
+			preg_match( '/(?:-|\.)min.css/iU', $url )
+			&&
+			false === stripos( $content, '@font-face' )
+		) {
+			Logger::error(
+				'Do not apply font display swap on min.css files without font-face.',
+				[
+					'css minification process',
+					'path' => $minified_file,
+				]
+			);
+
+			if ( ! $this->is_external_file( $url ) ) {
+				return '';
+			}
+
+			return $content;
+		}
+
+		return $this->apply_font_display_swap( $content );
+	}
+
+	/**
+	 * Minifies the content
+	 *
+	 * @since 2.11
+	 *
+	 * @param string $file_path     Source filepath.
+	 * @param string $minified_file Target filepath.
+	 * @param string $file_content  Content to minify.
+	 * @return string
+	 */
+	protected function minify( $file_path, $minified_file, $file_content ) {
+		$file_content     = $this->rewrite_paths( $file_path, $minified_file, $file_content );
+		$minifier         = $this->get_minifier( $file_content );
+		$minified_content = $minifier->minify();
+
+		if ( empty( $minified_content ) ) {
+			Logger::error(
+				'No minified content.',
+				[
+					'css minification process',
+					'path' => $minified_file,
+				]
+			);
+			return '';
+		}
+
+		return $minified_content;
+	}
+
+	/**
+	 * Returns a new minifier instance
+	 *
+	 * @since 3.1
+	 *
+	 * @param string $file_content Content to minify.
+	 * @return Minifier\CSS
+	 */
+	protected function get_minifier( $file_content ) {
+		return new Minifier\CSS( $file_content );
+	}
+}

wp-content/plugins/wp-rocket/inc/Engine/Optimization/Minify/CSS/Subscriber.php

@@ -0,0 +1,85 @@
+<?php
+namespace WP_Rocket\Engine\Optimization\Minify\CSS;
+
+use WP_Rocket\Engine\Optimization\AssetsLocalCache;
+use WP_Rocket\Engine\Optimization\Minify\AbstractMinifySubscriber;
+
+/**
+ * Minify/Combine CSS subscriber
+ *
+ * @since 3.1
+ */
+class Subscriber extends AbstractMinifySubscriber {
+	/**
+	 * Return an array of events that this subscriber wants to listen to.
+	 *
+	 * @since  3.1
+	 *
+	 * @return array
+	 */
+	public static function get_subscribed_events() {
+		$events = [
+			'rocket_css_url' => [
+				[ 'fix_ssl_minify' ],
+				[ 'i18n_multidomain_url' ],
+			],
+			'rocket_buffer'  => [ 'process', 16 ],
+		];
+
+		return $events;
+	}
+
+	/**
+	 * Processes the HTML to Minify/Combine CSS.
+	 *
+	 * @since 3.1
+	 *
+	 * @param string $html HTML content.
+	 * @return string
+	 */
+	public function process( $html ) {
+		if ( ! $this->is_allowed() ) {
+			return $html;
+		}
+
+		$assets_local_cache = new AssetsLocalCache( rocket_get_constant( 'WP_ROCKET_MINIFY_CACHE_PATH' ), $this->filesystem );
+
+		if ( $this->options->get( 'minify_css' ) && $this->options->get( 'minify_concatenate_css' ) ) {
+			$this->set_processor_type( new Combine( $this->options, $assets_local_cache ) );
+		} elseif ( $this->options->get( 'minify_css' ) && ! $this->options->get( 'minify_concatenate_css' ) ) {
+			$this->set_processor_type( new Minify( $this->options, $assets_local_cache ) );
+		}
+
+		return $this->processor->optimize( $html );
+	}
+
+	/**
+	 * Checks if is allowed to Minify/Combine CSS.
+	 *
+	 * @since 3.1
+	 *
+	 * @return bool
+	 */
+	protected function is_allowed() {
+		if ( rocket_get_constant( 'DONOTROCKETOPTIMIZE' ) ) {
+			return false;
+		}
+
+		if ( ! (bool) $this->options->get( 'minify_css', 0 ) ) {
+			return false;
+		}
+
+		return ! is_rocket_post_excluded_option( 'minify_css' );
+	}
+
+	/**
+	 * Returns an array of CDN zones for CSS files.
+	 *
+	 * @since 3.1
+	 *
+	 * @return array
+	 */
+	public function get_zones() {
+		return [ 'all', 'css_and_js', 'css' ];
+	}
+}