futtta / autoptimize

                    if ( apply_filters( 'autoptimize_filter_css_critcss_minify', true ) ) {

                        $iCssHash = md5( $defer_inline_code );

                        $iCssCache = new autoptimizeCache( $iCssHash, 'css' );

                        if ( $iCssCache->check() ) {

                            // we have the optimized inline CSS in cache.

                            $defer_inline_code = $iCssCache->retrieve();

                        } else {

                            $cssmin   = new autoptimizeCSSmin();

                            $tmp_code = trim( $cssmin->run( $defer_inline_code ) );

                            if ( ! empty( $tmp_code ) ) {

                                $defer_inline_code = $tmp_code;

                                $iCssCache->cache( $defer_inline_code, 'text/css' );

                                unset( $tmp_code );

                            }

                        }

                    }

                    $code_out = '<style type="text/css" id="aoatfcss" media="all">' . $defer_inline_code . '</style>';

                    $this->inject_in_html( $code_out, $replaceTag );

        $cache = new autoptimizeCache( $hash, 'css' );

        // If not in cache already, minify...

        if ( ! $cache->check() || $cache_miss ) {

            // Fixurls...

            $contents = self::fixurls( $filepath, $contents );

            // CDN-replace any referenced assets if needed...

            $contents = $this->replace_urls( $contents );

            // Now minify...

            $cssmin   = new autoptimizeCSSmin();

            $contents = trim( $cssmin->run( $contents ) );

            // Store in cache.

            $cache->cache( $contents, 'text/css' );

        }

        $url = $this->build_minify_single_url( $cache );