Чистка css-стилей при помощи PHP

<?php
            $css_rules = array();
            $css_end_rules = array();
            $css_end_rules_done = array();
            $css_start = file_get_contents("path/to/css.stylesheet");
            $css = $css_start;

            while(strpos($css,'media') !== FALSE) {
                $stop = false;
                preg_match("/(@(.+){(.+){(.+);\s?}}){1}/mU",$css,$matches);
                $css = str_replace($matches[0],'',$css);

                foreach($matches as $k=>$v) { if($v != $matches[0] && !$stop) {
                    $nk = '@'.$v;
                    if(!$css_rules[$nk]) $css_rules[$nk] = '';
                    $css_rules[$nk] = $css_rules[$nk].trim(substr(str_replace($nk,'',$matches[0]),1,-1));
                    $stop = true;
                } }

            }
            $css_rules['regular'] = $css;

            $i = 0;
            foreach($css_rules as $k=>$v) { if($i == 0) { $i++; } else {
                $new_css_parts = explode('}',$v);
                foreach($new_css_parts as $ncpk=>$ncpv) {
                    $new_css_rules = explode('{',$ncpv);
                    if(!$css_end_rules[$k][$new_css_rules[0]] && $new_css_rules[1]) $css_end_rules[$k][$new_css_rules[0]] = '';
                    if($new_css_rules[1]) $css_end_rules[$k][trim($new_css_rules[0])] = $css_end_rules[$k][$new_css_rules[0]].trim($new_css_rules[1]);
                }
            } }

            foreach($css_end_rules as $k=>$v) {
                $nk = (substr($k,-1)==' ')?substr($k,0,strlen($k)-1):$k;
                if(!is_array($css_end_rules_done[trim($nk)])) $css_end_rules_done[trim($nk)] = array();

                foreach($v as $id=>$css_group) {
                    if(!$css_group) {
                        unset($v[$id]);
                    } else {
                        $nid = (substr($id,-1)==' ')?substr($id,0,strlen($id)-1):$id;
                        if(!is_array($css_end_rules_done[$nk][trim($nid)])) $css_end_rules_done[$nk][trim($nid)] = array();
                        $groups = explode(';',$css_group);

                        foreach($groups as $gv) {
                            $rule = explode(':',$gv);
                            if(trim($rule[0]) && trim($rule[1]) && strpos($rule[0],'//')===FALSE) $css_end_rules_done[$nk][$id][trim($rule[0])] = trim($rule[1]);
                        }
                    }
                }
            }

            arsort($css_end_rules_done);

            $regular_css = $css_end_rules_done['regular'];
            unset($css_end_rules_done['regular']);

            $tab = "    ";
            $double_tab = $tab.$tab;
            $triple_tab = $tab.$double_tab;
            $end_css_style = "";
            foreach($css_end_rules_done as $group_media=>$rules) {
                $end_css_style = $end_css_style.trim($group_media." {").PHP_EOL;

                foreach($rules as $id=>$rule) {
                    $end_css_style = $end_css_style.$tab.trim($id." {").PHP_EOL;

                    foreach($rule as $param=>$value) {
                        $end_css_style = $end_css_style.$double_tab.$param.": ".trim($value).";".PHP_EOL;
                    }

                    $end_css_style = $end_css_style.$tab."}".PHP_EOL;
                }

                $end_css_style = $end_css_style."}".PHP_EOL;
            }

            foreach($regular_css as $id=>$rule) {
                $end_css_style = $end_css_style.trim($id." {").PHP_EOL;

                foreach($rule as $param=>$value) {
                    $end_css_style = $end_css_style.$tab.$param.": ".trim($value).";".PHP_EOL;
                }

                $end_css_style = $end_css_style."}".PHP_EOL;
            }
            echo '<pre>';
            echo $end_css_style;
            echo '</pre>';

            /*
            echo '<pre>';
            print_r($css_end_rules_done);
            echo '</pre>';
            */

            //echo '<br>';
            //echo $css_start;
?>