class MinificationSubscriber

class MinificationSubscriber implements EventSubscriberInterface {
    
    /**
     * The minifier.
     *
     * @var \Drupal\advagg\Asset\SingleAssetOptimizerBase
     */
    protected $minifier;
    
    /**
     * The minifier configuration.
     *
     * @var \Drupal\Core\Config\Config
     */
    protected $config;
    
    /**
     * Construct the optimizer instance.
     *
     * @param \Drupal\advagg\Asset\SingleAssetOptimizerBase $minifier
     *   The minifier.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory.
     */
    public function __construct(SingleAssetOptimizerBase $minifier, ConfigFactoryInterface $config_factory) {
        $this->minifier = $minifier;
        $this->config = $config_factory->get('advagg_ext_minify.settings');
    }
    
    /**
     * Pass the minification over to the minification service.
     *
     * @param \Drupal\advagg\Asset\AssetOptimizationEvent $asset
     *   The asset optimization event.
     */
    public function minifyCss(AssetOptimizationEvent $asset) {
        if (!$this->isEnabled('css')) {
            return;
        }
        $content = $asset->getContent();
        $content = $this->minifier
            ->css($content, $asset->getAsset(), $asset->getData());
        $asset->setContent($content);
    }
    
    /**
     * Pass the minification over to the minification service.
     *
     * @param \Drupal\advagg\Asset\AssetOptimizationEvent $asset
     *   The asset optimization event.
     */
    public function minifyJs(AssetOptimizationEvent $asset) {
        if (!$this->isEnabled('js')) {
            return;
        }
        $content = $asset->getContent();
        $content = $this->minifier
            ->js($content, $asset->getAsset(), $asset->getData());
        $asset->setContent($content);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() {
        return [
            AssetOptimizationEvent::CSS => [
                'minifyCss',
                0,
            ],
            AssetOptimizationEvent::JS => [
                'minifyJs',
                0,
            ],
        ];
    }
    
    /**
     * Check if the external minifier is enabled & configured for this asset type.
     *
     * @param string $type
     *   The asset type.
     *
     * @return bool
     *   Whether to run the external minifier or not.
     */
    protected function isEnabled($type) {
        if (!$this->config
            ->get("{$type}_enabled")) {
            return FALSE;
        }
        if (!$this->config
            ->get("{$type}_cmd")) {
            return FALSE;
        }
        return TRUE;
    }

}