Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\Asset;
Chris@0: 
Chris@0: use Drupal\Component\Utility\Unicode;
Chris@0: 
Chris@0: /**
Chris@0:  * Optimizes a CSS asset.
Chris@0:  */
Chris@0: class CssOptimizer implements AssetOptimizerInterface {
Chris@0: 
Chris@0:   /**
Chris@0:    * The base path used by rewriteFileURI().
Chris@0:    *
Chris@0:    * @var string
Chris@0:    */
Chris@0:   public $rewriteFileURIBasePath;
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public function optimize(array $css_asset) {
Chris@0:     if ($css_asset['type'] != 'file') {
Chris@0:       throw new \Exception('Only file CSS assets can be optimized.');
Chris@0:     }
Chris@0:     if (!$css_asset['preprocess']) {
Chris@0:       throw new \Exception('Only file CSS assets with preprocessing enabled can be optimized.');
Chris@0:     }
Chris@0: 
Chris@0:     return $this->processFile($css_asset);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Processes the contents of a CSS asset for cleanup.
Chris@0:    *
Chris@0:    * @param string $contents
Chris@0:    *   The contents of the CSS asset.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   Contents of the CSS asset.
Chris@0:    */
Chris@0:   public function clean($contents) {
Chris@0:     // Remove multiple charset declarations for standards compliance (and fixing
Chris@0:     // Safari problems).
Chris@0:     $contents = preg_replace('/^@charset\s+[\'"](\S*?)\b[\'"];/i', '', $contents);
Chris@0: 
Chris@0:     return $contents;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Build aggregate CSS file.
Chris@0:    */
Chris@0:   protected function processFile($css_asset) {
Chris@0:     $contents = $this->loadFile($css_asset['data'], TRUE);
Chris@0: 
Chris@0:     $contents = $this->clean($contents);
Chris@0: 
Chris@0:     // Get the parent directory of this file, relative to the Drupal root.
Chris@0:     $css_base_path = substr($css_asset['data'], 0, strrpos($css_asset['data'], '/'));
Chris@0:     // Store base path.
Chris@0:     $this->rewriteFileURIBasePath = $css_base_path . '/';
Chris@0: 
Chris@0:     // Anchor all paths in the CSS with its base URL, ignoring external and absolute paths.
Chris@0:     return preg_replace_callback('/url\(\s*[\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\s*\)/i', [$this, 'rewriteFileURI'], $contents);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Loads the stylesheet and resolves all @import commands.
Chris@0:    *
Chris@0:    * Loads a stylesheet and replaces @import commands with the contents of the
Chris@0:    * imported file. Use this instead of file_get_contents when processing
Chris@0:    * stylesheets.
Chris@0:    *
Chris@0:    * The returned contents are compressed removing white space and comments only
Chris@0:    * when CSS aggregation is enabled. This optimization will not apply for
Chris@0:    * color.module enabled themes with CSS aggregation turned off.
Chris@0:    *
Chris@0:    * Note: the only reason this method is public is so color.module can call it;
Chris@0:    * it is not on the AssetOptimizerInterface, so future refactorings can make
Chris@0:    * it protected.
Chris@0:    *
Chris@0:    * @param $file
Chris@0:    *   Name of the stylesheet to be processed.
Chris@0:    * @param $optimize
Chris@0:    *   Defines if CSS contents should be compressed or not.
Chris@0:    * @param $reset_basepath
Chris@0:    *   Used internally to facilitate recursive resolution of @import commands.
Chris@0:    *
Chris@0:    * @return
Chris@0:    *   Contents of the stylesheet, including any resolved @import commands.
Chris@0:    */
Chris@0:   public function loadFile($file, $optimize = NULL, $reset_basepath = TRUE) {
Chris@0:     // These statics are not cache variables, so we don't use drupal_static().
Chris@0:     static $_optimize, $basepath;
Chris@0:     if ($reset_basepath) {
Chris@0:       $basepath = '';
Chris@0:     }
Chris@0:     // Store the value of $optimize for preg_replace_callback with nested
Chris@0:     // @import loops.
Chris@0:     if (isset($optimize)) {
Chris@0:       $_optimize = $optimize;
Chris@0:     }
Chris@0: 
Chris@0:     // Stylesheets are relative one to each other. Start by adding a base path
Chris@0:     // prefix provided by the parent stylesheet (if necessary).
Chris@0:     if ($basepath && !file_uri_scheme($file)) {
Chris@0:       $file = $basepath . '/' . $file;
Chris@0:     }
Chris@0:     // Store the parent base path to restore it later.
Chris@0:     $parent_base_path = $basepath;
Chris@0:     // Set the current base path to process possible child imports.
Chris@0:     $basepath = dirname($file);
Chris@0: 
Chris@0:     // Load the CSS stylesheet. We suppress errors because themes may specify
Chris@0:     // stylesheets in their .info.yml file that don't exist in the theme's path,
Chris@0:     // but are merely there to disable certain module CSS files.
Chris@0:     $content = '';
Chris@0:     if ($contents = @file_get_contents($file)) {
Chris@0:       // If a BOM is found, convert the file to UTF-8, then use substr() to
Chris@0:       // remove the BOM from the result.
Chris@0:       if ($encoding = (Unicode::encodingFromBOM($contents))) {
Chris@17:         $contents = mb_substr(Unicode::convertToUtf8($contents, $encoding), 1);
Chris@0:       }
Chris@0:       // If no BOM, check for fallback encoding. Per CSS spec the regex is very strict.
Chris@0:       elseif (preg_match('/^@charset "([^"]+)";/', $contents, $matches)) {
Chris@0:         if ($matches[1] !== 'utf-8' && $matches[1] !== 'UTF-8') {
Chris@0:           $contents = substr($contents, strlen($matches[0]));
Chris@0:           $contents = Unicode::convertToUtf8($contents, $matches[1]);
Chris@0:         }
Chris@0:       }
Chris@0: 
Chris@0:       // Return the processed stylesheet.
Chris@0:       $content = $this->processCss($contents, $_optimize);
Chris@0:     }
Chris@0: 
Chris@0:     // Restore the parent base path as the file and its children are processed.
Chris@0:     $basepath = $parent_base_path;
Chris@0:     return $content;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Loads stylesheets recursively and returns contents with corrected paths.
Chris@0:    *
Chris@0:    * This function is used for recursive loading of stylesheets and
Chris@0:    * returns the stylesheet content with all url() paths corrected.
Chris@0:    *
Chris@0:    * @param array $matches
Chris@0:    *   An array of matches by a preg_replace_callback() call that scans for
Chris@0:    *   @import-ed CSS files, except for external CSS files.
Chris@0:    *
Chris@0:    * @return
Chris@0:    *   The contents of the CSS file at $matches[1], with corrected paths.
Chris@0:    *
Chris@0:    * @see \Drupal\Core\Asset\AssetOptimizerInterface::loadFile()
Chris@0:    */
Chris@0:   protected function loadNestedFile($matches) {
Chris@0:     $filename = $matches[1];
Chris@0:     // Load the imported stylesheet and replace @import commands in there as
Chris@0:     // well.
Chris@0:     $file = $this->loadFile($filename, NULL, FALSE);
Chris@0: 
Chris@0:     // Determine the file's directory.
Chris@0:     $directory = dirname($filename);
Chris@0:     // If the file is in the current directory, make sure '.' doesn't appear in
Chris@0:     // the url() path.
Chris@0:     $directory = $directory == '.' ? '' : $directory . '/';
Chris@0: 
Chris@0:     // Alter all internal url() paths. Leave external paths alone. We don't need
Chris@0:     // to normalize absolute paths here because that will be done later.
Chris@0:     return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)([^\'")]+)([\'"]?)\s*\)/i', 'url(\1' . $directory . '\2\3)', $file);
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Processes the contents of a stylesheet for aggregation.
Chris@0:    *
Chris@0:    * @param $contents
Chris@0:    *   The contents of the stylesheet.
Chris@0:    * @param $optimize
Chris@0:    *   (optional) Boolean whether CSS contents should be minified. Defaults to
Chris@0:    *   FALSE.
Chris@0:    *
Chris@0:    * @return
Chris@0:    *   Contents of the stylesheet including the imported stylesheets.
Chris@0:    */
Chris@0:   protected function processCss($contents, $optimize = FALSE) {
Chris@0:     // Remove unwanted CSS code that cause issues.
Chris@0:     $contents = $this->clean($contents);
Chris@0: 
Chris@0:     if ($optimize) {
Chris@0:       // Perform some safe CSS optimizations.
Chris@0:       // Regexp to match comment blocks.
Chris@17:       $comment = '/\*[^*]*\*+(?:[^/*][^*]*\*+)*/';
Chris@0:       // Regexp to match double quoted strings.
Chris@0:       $double_quot = '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"';
Chris@0:       // Regexp to match single quoted strings.
Chris@0:       $single_quot = "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'";
Chris@0:       // Strip all comment blocks, but keep double/single quoted strings.
Chris@0:       $contents = preg_replace(
Chris@0:         "<($double_quot|$single_quot)|$comment>Ss",
Chris@0:         "$1",
Chris@0:         $contents
Chris@0:       );
Chris@0:       // Remove certain whitespace.
Chris@0:       // There are different conditions for removing leading and trailing
Chris@0:       // whitespace.
Chris@0:       // @see http://php.net/manual/regexp.reference.subpatterns.php
Chris@0:       $contents = preg_replace('<
Chris@0:         # Do not strip any space from within single or double quotes
Chris@0:           (' . $double_quot . '|' . $single_quot . ')
Chris@0:         # Strip leading and trailing whitespace.
Chris@0:         | \s*([@{};,])\s*
Chris@0:         # Strip only leading whitespace from:
Chris@0:         # - Closing parenthesis: Retain "@media (bar) and foo".
Chris@0:         | \s+([\)])
Chris@0:         # Strip only trailing whitespace from:
Chris@0:         # - Opening parenthesis: Retain "@media (bar) and foo".
Chris@0:         # - Colon: Retain :pseudo-selectors.
Chris@0:         | ([\(:])\s+
Chris@0:       >xSs',
Chris@0:         // Only one of the four capturing groups will match, so its reference
Chris@0:         // will contain the wanted value and the references for the
Chris@0:         // two non-matching groups will be replaced with empty strings.
Chris@0:         '$1$2$3$4',
Chris@0:         $contents
Chris@0:       );
Chris@0:       // End the file with a new line.
Chris@0:       $contents = trim($contents);
Chris@0:       $contents .= "\n";
Chris@0:     }
Chris@0: 
Chris@0:     // Replaces @import commands with the actual stylesheet content.
Chris@0:     // This happens recursively but omits external files.
Chris@0:     $contents = preg_replace_callback('/@import\s*(?:url\(\s*)?[\'"]?(?![a-z]+:)(?!\/\/)([^\'"\()]+)[\'"]?\s*\)?\s*;/', [$this, 'loadNestedFile'], $contents);
Chris@0: 
Chris@0:     return $contents;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Prefixes all paths within a CSS file for processFile().
Chris@0:    *
Chris@0:    * Note: the only reason this method is public is so color.module can call it;
Chris@0:    * it is not on the AssetOptimizerInterface, so future refactorings can make
Chris@0:    * it protected.
Chris@0:    *
Chris@0:    * @param array $matches
Chris@0:    *   An array of matches by a preg_replace_callback() call that scans for
Chris@0:    *   url() references in CSS files, except for external or absolute ones.
Chris@0:    *
Chris@0:    * @return string
Chris@0:    *   The file path.
Chris@0:    */
Chris@0:   public function rewriteFileURI($matches) {
Chris@0:     // Prefix with base and remove '../' segments where possible.
Chris@0:     $path = $this->rewriteFileURIBasePath . $matches[1];
Chris@0:     $last = '';
Chris@0:     while ($path != $last) {
Chris@0:       $last = $path;
Chris@0:       $path = preg_replace('`(^|/)(?!\.\./)([^/]+)/\.\./`', '$1', $path);
Chris@0:     }
Chris@0:     return 'url(' . file_url_transform_relative(file_create_url($path)) . ')';
Chris@0:   }
Chris@0: 
Chris@0: }