/**
    * This file Copyright (c) 2015-2016 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.imaging;
  
  import info.magnolia.module.ModuleLifecycle;
  import info.magnolia.module.ModuleLifecycleContext;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeSet;
  
  import javax.imageio.ImageIO;
  import javax.imageio.spi.IIORegistry;
  import javax.imageio.spi.ServiceRegistry;
  
  import org.apache.commons.collections4.CollectionUtils;
  import org.apache.commons.collections4.Transformer;
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Keeps the configuration of the imaging module.
   */
  public class ImagingModule implements ModuleLifecycle {
  
      private static final Logger log = LoggerFactory.getLogger(ImagingModule.class);
  
      public static final String IMAGING = "imaging";
  
      private Map<String, ImageGenerator> generators = new LinkedHashMap<String, ImageGenerator>();
      private boolean storeGeneratedImages = true;
  
      public void setGenerators(Map<String, ImageGenerator> generators) {
          this.generators = generators;
      }
  
      public Map<String, ImageGenerator> getGenerators() {
          return generators;
      }
  
      public boolean isStoreGeneratedImages() {
          return storeGeneratedImages;
      }
  
      public void setStoreGeneratedImages(boolean storeGeneratedImages) {
          this.storeGeneratedImages = storeGeneratedImages;
      }
  
      /**
       * Scan for additional plugins when module starts.
       *
       * @see ImageIO#scanForPlugins()
       */
      @Override
      public void start(ModuleLifecycleContext moduleLifecycleContext) {
          ImageIO.scanForPlugins();
  
          // Outputting supported formats was previously done by the now extinct module info.magnolia:magnolia-module-imagingtools
          if (log.isDebugEnabled()) {
              log.debug("This lists the formats currently available to the javax.imageio package, as installed on this system.");
              log.debug("Supported input formats:     {}", StringUtils.join(filter(ImageIO.getReaderFormatNames()), ", "));
              log.debug("Supported input mime types:  {}", StringUtils.join(filter(ImageIO.getReaderMIMETypes()), ", "));
             log.debug("Supported output formats:    {}", StringUtils.join(filter(ImageIO.getWriterFormatNames()), ", "));
             log.debug("Supported output mime types: {}", StringUtils.join(filter(ImageIO.getWriterMIMETypes()), ", "));
         }
     }
 
     /**
      * De-registers all plugins which have the {@link Thread#getContextClassLoader() current thread's context class loader}
      * as its class loader when the module is stopped, to avoid class/resource leak.
      *
      * This is taken from com.twelvemonkeys.servlet.image.IIOProviderContextListener and the details are explained here:
      * https://github.com/haraldk/TwelveMonkeys#deploying-the-plugins-in-a-web-app .
      */
     @Override
     public void stop(ModuleLifecycleContext moduleLifecycleContext) {
 
         // De-register any locally registered IIO plugins. Relies on each web app having its own context class loader.
         final IIORegistry registry = IIORegistry.getDefaultInstance();
         final LocalFilter localFilter = new LocalFilter(Thread.currentThread().getContextClassLoader());
 
         Iterator<Class<?>> categories = registry.getCategories();
 
         while (categories.hasNext()) {
             Class<?> category = categories.next();
             Iterator<?> providers = registry.getServiceProviders(category, localFilter, false);
 
             // Copy the providers, as de-registering while iterating over providers will lead to ConcurrentModificationExceptions.
             List<Object> providersCopy = new ArrayList<>();
             while (providers.hasNext()) {
                 providersCopy.add(providers.next());
             }
 
             for (Object provider : providersCopy) {
                 registry.deregisterServiceProvider(provider);
                 log.debug("Unregistered locally installed provider class: {}", provider.getClass());
             }
         }
     }
 
     /**
      * Filters the providers based on their class loader.
      */
     static class LocalFilter implements ServiceRegistry.Filter {
         private final ClassLoader loader;
 
         public LocalFilter(ClassLoader loader) {
             this.loader = loader;
         }
 
         @Override
         public boolean filter(Object provider) {
             return provider.getClass().getClassLoader() == loader;
         }
     }
 
     /**
      * Removes duplicates and returns a collection of all entries in lowercase.
      */
     private Collection<String> filter(String... formats) {
         final TreeSet<String> set = new TreeSet<>(String.CASE_INSENSITIVE_ORDER);
         set.addAll(Arrays.asList(formats));
         CollectionUtils.transform(set, new Transformer() {
             @Override
             public Object transform(Object input) {
                 return ((String) input).toLowerCase();
             }
         });
         return set;
     }
 }