class SingleAssetOptimizerBase

abstract class SingleAssetOptimizerBase {
    
    /**
     * Logger service.
     *
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;
    
    /**
     * A config object for optimizer.
     *
     * @var \Drupal\Core\Config\Config
     */
    protected $config;
    
    /**
     * The file URL generator.
     *
     * @var \Drupal\Core\File\FileUrlGeneratorInterface
     */
    protected $fileUrlGenerator;
    
    /**
     * Construct the optimizer.
     *
     * @param \Psr\Log\LoggerInterface $logger
     *   A PSR compatible logger.
     * @param \Drupal\Core\File\FileUrlGeneratorInterface $file_url_generator
     *   The file URL generator.
     */
    public function __construct(LoggerInterface $logger, FileUrlGeneratorInterface $file_url_generator) {
        $this->logger = $logger;
        $this->fileUrlGenerator = $file_url_generator;
    }
    
    /**
     * Optimize the asset's content.
     *
     * @param string $content
     *   The content to optimize.
     * @param array $asset
     *   A core asset array.
     * @param array $data
     *   The cache data.
     *
     * @return string
     *   The optimized content.
     */
    public abstract function optimize($content, array $asset, array $data);
    
    /**
     * If configured, add licence string to top/bottom of file.
     *
     * @param string $contents
     *   The file contents.
     * @param string $path
     *   The original file path.
     */
    public function addLicense(&$contents, $path) {
        if ($this->config
            ->get('add_license')) {
            $url = $this->fileUrlGenerator
                ->generateAbsoluteString($path);
            $contents = "/* Source and licensing information for the line(s) below can be found at {$url}. */\n" . $contents . "\n/* Source and licensing information for the above line(s) can be found at {$url}. */";
        }
    }
    
    /**
     * Checks if string contains multibyte characters.
     *
     * @param string $string
     *   String to check.
     *
     * @return bool
     *   TRUE if string contains multibyte character.
     */
    protected function stringContainsMultibyteCharacters($string) {
        // Check if there are multi-byte characters: If the UTF-8 encoded string has
        // multibyte chars strlen() will return a byte-count greater than the actual
        // character count, returned by drupal_strlen().
        if (strlen($string) === mb_strlen($string)) {
            return FALSE;
        }
        return TRUE;
    }
    
    /**
     * Check if the asset is already minified.
     *
     * @param string $contents
     *   The asset contents.
     *
     * @return bool
     *   TRUE if the asset appears to be already minified.
     */
    protected function isMinified($contents) {
        // If a lot of semicolons probably already minified.
        $semicolon_count = substr_count($contents, ';');
        if ($semicolon_count > 10 && $semicolon_count > substr_count($contents, "\n")) {
            return TRUE;
        }
        return FALSE;
    }
    
    /**
     * Check if minification was successful before saving changes.
     *
     * @param string $minified
     *   The minified asset contents.
     * @param string $original
     *   The original asset contents to compare against.
     *
     * @return bool
     *   TRUE for success.
     */
    protected function isMinificationSuccess($minified, $original) {
        // If the minified data is zero length it was a failure.
        if (empty($minified)) {
            return FALSE;
        }
        // If set, make sure the minified version doesn't have a suspiciously high
        // ratio or conversely a really low ratio.
        if (!$this->config
            ->get('ratio_max')) {
            return TRUE;
        }
        $before = strlen($original);
        $after = strlen($minified);
        $ratio = !empty($before) ? ($before - $after) / $before : 0;
        if ($ratio > $this->config
            ->get('ratio_max') || $ratio < $this->config
            ->get('ratio_min')) {
            return FALSE;
        }
        return TRUE;
    }

}