package org.eclipse.aether.internal.impl.filter;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *  http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.stream.Collectors;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.impl.RemoteRepositoryFilterManager;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.repository.RemoteRepository;
  import org.eclipse.aether.spi.connector.filter.RemoteRepositoryFilter;
  import org.eclipse.aether.spi.connector.filter.RemoteRepositoryFilterSource;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Default implementation of {@link RemoteRepositoryFilterManager}, it always returns a {@link RemoteRepositoryFilter}
   * instance, even if no filter sources enabled/registered (then "always allow" instance).
   * <p>
   * The created {@link RemoteRepositoryFilter} instance is created once per session and cached.
   *
   * @since 1.9.0
   */
  @Singleton
  @Named
  public final class DefaultRemoteRepositoryFilterManager
          implements RemoteRepositoryFilterManager
  {
      private static final String INSTANCE_KEY = DefaultRemoteRepositoryFilterManager.class.getName() + ".instance";
  
      private final Map<String, RemoteRepositoryFilterSource> sources;
  
      /**
       * SL enabled ctor.
       *
       * @deprecated for SL and testing purposes only.
       */
      @Deprecated
      public DefaultRemoteRepositoryFilterManager()
      {
          this.sources = new HashMap<>();
      }
  
      @Inject
      public DefaultRemoteRepositoryFilterManager( Map<String, RemoteRepositoryFilterSource> sources )
      {
          this.sources = requireNonNull( sources );
      }
  
      @Override
      public RemoteRepositoryFilter getRemoteRepositoryFilter( RepositorySystemSession session )
      {
          return (RemoteRepositoryFilter) session.getData().computeIfAbsent( INSTANCE_KEY, () ->
                  {
                      HashMap<String, RemoteRepositoryFilter> filters = new HashMap<>();
                      for ( Map.Entry<String, RemoteRepositoryFilterSource> entry : sources.entrySet() )
                      {
                          RemoteRepositoryFilter filter = entry.getValue().getRemoteRepositoryFilter( session );
                          if ( filter != null )
                          {
                              filters.put( entry.getKey(), filter );
                          }
                      }
                      if ( !filters.isEmpty() )
                      {
                          return new Participants( filters );
                      }
                      else
                      {
                          return null;
                      }
                  }
          );
      }
 
     /**
      * {@link RemoteRepositoryFilter} instance when there are participant filters present. It evaluates into result
      * using {@link Consensus}.
      */
     private static class Participants implements RemoteRepositoryFilter
     {
         private final Map<String, RemoteRepositoryFilter> participants;
 
         private Participants( Map<String, RemoteRepositoryFilter> participants )
         {
             this.participants = Collections.unmodifiableMap( participants );
         }
 
         @Override
         public RemoteRepositoryFilter.Result acceptArtifact( RemoteRepository remoteRepository, Artifact artifact )
         {
             return new Consensus( participants.entrySet().stream()
                     .collect( Collectors.toMap(
                             Map.Entry::getKey,
                             e -> e.getValue().acceptArtifact( remoteRepository, artifact ) ) ) );
         }
 
         @Override
         public RemoteRepositoryFilter.Result acceptMetadata( RemoteRepository remoteRepository, Metadata metadata )
         {
             return new Consensus( participants.entrySet().stream()
                     .collect( Collectors.toMap(
                             Map.Entry::getKey,
                             e -> e.getValue().acceptMetadata( remoteRepository, metadata ) ) ) );
         }
     }
 
     /**
      * {@link RemoteRepositoryFilter.Result} based on "consensus". All participant have to "accept" to make this
      * instance "accept".
      */
     private static class Consensus implements RemoteRepositoryFilter.Result
     {
         private final boolean accepted;
 
         private final String reasoning;
 
         Consensus( Map<String, RemoteRepositoryFilter.Result> results )
         {
             this.accepted = results.values().stream().allMatch( RemoteRepositoryFilter.Result::isAccepted );
             this.reasoning = results.values().stream().filter( r -> !r.isAccepted() ).map(
                     RemoteRepositoryFilter.Result::reasoning ).collect(
                     Collectors.joining( "; " ) );
         }
 
         @Override
         public boolean isAccepted()
         {
             return accepted;
         }
 
         @Override
         public String reasoning()
         {
             return reasoning;
         }
     }
 }