Jarves\AssetHandler\CssHandler::compressFiles PHP Method

    public function compressFiles(array $files)
    {
        $md5String = '';
        foreach ($files as $file) {
            $path = $this->getAssetPath($file);
            $md5String .= '.' . filemtime($path);
        }
        $fileUpToDate = false;
        $md5Line = '/* ' . md5($md5String) . " */\n";
        $oFile = 'cache/compressed-css/' . md5($md5String) . '.css';
        $handle = @fopen($this->getJarves()->getRootDir() . '/../web/' . $oFile, 'r');
        if ($handle) {
            $line = fgets($handle);
            fclose($handle);
            if ($line == $md5Line) {
                $fileUpToDate = true;
            }
        }
        if (!$fileUpToDate) {
            $content = $this->utils->compressCss($files, 'cache/compressed-css/');
            $content = $md5Line . $content;
            $this->webFilesystem->write($oFile, $content);
        }
        $assetInfo = new AssetInfo();
        $assetInfo->setPath($oFile);
        return $assetInfo;
    }