/**
    * This file Copyright (c) 2015 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.config.registry;
  
  import info.magnolia.config.source.ConfigurationSourceType;
  
  import java.util.Collection;
  import java.util.Set;
  
  import javax.inject.Inject;
  
  import com.google.common.base.Function;
  import com.google.common.base.Predicate;
  import com.google.common.collect.Collections2;
  import com.google.common.collect.Iterables;
  import com.google.common.collect.Lists;
  
  /**
   * Implementation of the {@link info.magnolia.config.registry.RegistryFacade}.
   */
  public class RegistryFacadeImpl implements RegistryFacade {
      private final Collection<Registry> registries;
  
      @Inject
      public RegistryFacadeImpl(Set<Registry> registries) {
          this.registries = registries;
          //TODO validate each registry is "unique" (registry.type())
      }
  
      @Override
      public Registry registryFor(final DefinitionType type) {
          return Iterables.find(registries, new RegistryByType(type));
      }
  
      @Override
      public Collection<Registry> all() {
          return registries;
      }
  
      @Override
      public Collection<DefinitionProvider> byModule(String moduleName) {
          return query().from(moduleName).findMultiple();
      }
  
      @Override
      public Collection<DefinitionProvider> byType(DefinitionType type) {
          return query().ofType(type).findMultiple();
      }
  
      @Override
      public Collection<DefinitionProvider> bySource(ConfigurationSourceType sourceType) {
          throw new IllegalStateException("not implemented yet");
      }
  
      @Override
      public DefinitionQuery query() {
          return new AggregatingQuery();
      }
  
      private class AggregatingQuery extends DefinitionQuery {
          @Override
          public Collection<DefinitionProvider<?>> findMultiple() {
              final Collection<Registry> allRegistries = all();
              // collect results from each registry
              final Collection<Collection<? extends DefinitionProvider<?>>> allRes = Collections2.transform(allRegistries,
                      new RegistryCollectionFunction(this));
              // concat them in a single list
              return Lists.newLinkedList(Iterables.concat(allRes));
         }
 
 
         private class RegistryCollectionFunction implements Function<Registry, Collection<? extends DefinitionProvider<?>>> {
             private final AggregatingQuery query;
 
             public RegistryCollectionFunction(AggregatingQuery query) {
                 this.query = query;
             }
 
             @Override
             public Collection<? extends DefinitionProvider<?>> apply(final Registry registry) {
                 return ((DefinitionQuery<?>) copyFor(query, registry)).findMultiple();
             }
         }
 
     }
 
     // not public, only needed for RegFacadeImpl. Move or make public ? TODO how we do ensure we copied it right ?
     // --> unit test ? (if we add props to queries... need to make sure we can still copy it)
     private static DefinitionQuery<?> copyFor(AggregatingQuery src, Registry<?> registry) {
         return registry.query()
                 .from(src.getModule())
                 .at(src.getLocationPattern())
                 .ofType(src.getType())
                 .named(src.getName());
     }
 
 
     private static class RegistryByType implements Predicate<Registry> {
         private final DefinitionType type;
 
         public RegistryByType(DefinitionType type) {
             this.type = type;
         }
 
         @Override
         public boolean apply(Registry registry) {
             return registry.type().equals(type);
         }
     }
 
 }