/**
    * This file Copyright (c) 2017-2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.module.cache.flushpolicy;
  
  import info.magnolia.dirwatch.DirectoryWatcherService;
  import info.magnolia.dirwatch.WatcherCallback;
  import info.magnolia.init.MagnoliaConfigurationProperties;
  import info.magnolia.module.cache.Cache;
  import info.magnolia.module.cache.CacheFactory;
  import info.magnolia.module.cache.CacheModule;
  import info.magnolia.module.cache.FlushPolicy;
  import info.magnolia.resourceloader.file.FileSystemResourceOrigin;
  
  import java.io.IOException;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.regex.Pattern;
  
  import javax.inject.Inject;
  import javax.inject.Provider;
  
  /**
   * Simple flush policy that will empty whole cache in case of file system origin changes.
   */
  public class LightModuleChangesFlushPolicy implements FlushPolicy {
  
      private List<PathToCacheMapping> pathToCacheMappings = new ArrayList<>();
  
      private final Provider<CacheFactory> cacheFactoryProvider;
      private final DirectoryWatcherService directoryWatcherService;
      private final Path lightModulePath;
  
      @Inject
      public LightModuleChangesFlushPolicy(Provider<CacheFactory> cacheFactoryProvider, DirectoryWatcherService directoryWatcherService, MagnoliaConfigurationProperties properties) {
          this.cacheFactoryProvider = cacheFactoryProvider;
          this.directoryWatcherService = directoryWatcherService;
          this.lightModulePath = Paths.get(properties.getProperty(FileSystemResourceOrigin.RESOURCES_DIR_PROPERTY));
      }
  
      @Override
      public void start(Cache cache) {
          try {
              directoryWatcherService.register(lightModulePath, path -> true, new WatcherCallback() {
                  @Override
                  public void added(Path path) {
                      modified(path);
                  }
  
                  @Override
                  public void removed(Path path) {
                      modified(path);
                  }
  
                  @Override
                  public void modified(Path path) {
                      cacheFactoryProvider.get().getCacheNames().forEach((String cacheName) -> {
                          if (pathToCacheMappings.stream().anyMatch(pathToCacheMapping -> cacheName.equals(pathToCacheMapping.getCacheName()) && pathToCacheMapping.compiledPattern.matcher(lightModulePath.relativize(path).toString()).matches())) {
                              cacheFactoryProvider.get().getCache(cacheName).clear();
                          }
                      });
                  }
              });
          } catch (IOException e) {
              throw new RuntimeException(e);
          }
      }
 
     public List<PathToCacheMapping> getPathToCacheMappings() {
         return pathToCacheMappings;
     }
 
     public void setPathToCacheMappings(List<PathToCacheMapping> pathToCacheMappings) {
         this.pathToCacheMappings = pathToCacheMappings;
     }
 
     @Override
     public void stop(Cache cache) {
     }
 
     /**
      * Configuration class for assigning light module's directories to trigger cache flushing.
      */
     public static class PathToCacheMapping {
 
         private String cacheName = CacheModule.DEFAULT_CACHE_CONFIG;
         private String pattern = ".*";
 
         private Pattern compiledPattern;
 
         public void init() {
             compiledPattern = Pattern.compile(pattern);
         }
 
         public String getPattern() {
             return pattern;
         }
 
         public void setPattern(String pattern) {
             this.pattern = pattern;
         }
 
         public String getCacheName() {
             return cacheName;
         }
 
         public void setCacheName(String cacheName) {
             this.cacheName = cacheName;
         }
     }
 }