[WordPress] Nginx Cache Controller でデバイスごとにキャッシュキーを変更しているときにそれらのキャッシュを全部消す方法

gistfile1.php

<?php
function nginx_flush_cache( $url ) {
  if ( !$url )
    return;
  $params = array(
    '@ktai',
    '@smartphone',
    '@smartphone.off',
    );
  foreach ( $params as $param ) {
    NginxCachePurge::purge($url.$param);
  }
}
add_action('nginxchampuru_flush_cache', 'nginx_flush_cache');

Class NginxCachePurge {
  const CACHE_LEVELS = '1:2';
  const CACHE_DIR = '/var/cache/nginx/proxy_cache';
 
  public static function purge($url) {
    $cache_key = self::get_cache_key($url);
    $cache = self::get_cache_file($cache_key);
    if ( file_exists($cache) && @unlink($cache) ) {
      return true;
    } else {
      return false;
    }
  }
 
  private static function get_cache_key($url) {
    return md5($url);
  }
 
  private static function get_cache_file($key) {
    $levels  = get_option('nginxchampuru-cache_levels');
    $levels  = preg_split("/:/", $levels ? $levels : self::CACHE_LEVELS);
    $cache_dir = get_option('nginxchampuru-cache_dir');
    $path    = array();
    $path[]  = $cache_dir ? $cache_dir : self::CACHE_DIR;
    $offset  = 0;
    foreach ($levels as $l) {
      $offset = $offset + $l;
      $path[] = substr($key, 0-$offset, $l);
    }
    $path[] = $key;
    return join("/", $path);
  }
}