/*
    * 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.
   */
  package org.apache.maven.project;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.codehaus.plexus.classworlds.realm.ClassRealm;
  import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
  import org.eclipse.aether.graph.DependencyFilter;
  import org.eclipse.sisu.PreDestroy;
  
  /**
   * Default project realm cache implementation. Assumes cached data does not change.
   */
  @Singleton
  @Named
  public class DefaultProjectRealmCache implements ProjectRealmCache {
      /**
       * CacheKey
       */
      protected static class CacheKey implements Key {
  
          private final List<? extends ClassRealm> extensionRealms;
  
          private final int hashCode;
  
          public CacheKey(List<? extends ClassRealm> extensionRealms) {
              this.extensionRealms = (extensionRealms != null)
                      ? Collections.unmodifiableList(extensionRealms)
                      : Collections.<ClassRealm>emptyList();
  
              this.hashCode = this.extensionRealms.hashCode();
          }
  
          @Override
          public int hashCode() {
              return hashCode;
          }
  
          @Override
          public boolean equals(Object o) {
              if (o == this) {
                  return true;
              }
  
              if (!(o instanceof CacheKey)) {
                  return false;
              }
  
              CacheKey other = (CacheKey) o;
  
              return extensionRealms.equals(other.extensionRealms);
          }
  
          @Override
          public String toString() {
              return extensionRealms.toString();
          }
      }
  
      protected final Map<Key, CacheRecord> cache = new ConcurrentHashMap<>();
  
      @Override
      public Key createKey(List<? extends ClassRealm> extensionRealms) {
          return new CacheKey(extensionRealms);
      }
  
      public CacheRecord get(Key key) {
          return cache.get(key);
      }
  
      public CacheRecord put(Key key, ClassRealm projectRealm, DependencyFilter extensionArtifactFilter) {
          Objects.requireNonNull(projectRealm, "projectRealm cannot be null");
  
          if (cache.containsKey(key)) {
              throw new IllegalStateException("Duplicate project realm for extensions " + key);
         }
 
         CacheRecord record = new CacheRecord(projectRealm, extensionArtifactFilter);
 
         cache.put(key, record);
 
         return record;
     }
 
     public void flush() {
         for (CacheRecord record : cache.values()) {
             ClassRealm realm = record.getRealm();
             try {
                 realm.getWorld().disposeRealm(realm.getId());
             } catch (NoSuchRealmException e) {
                 // ignore
             }
         }
         cache.clear();
     }
 
     public void register(MavenProject project, Key key, CacheRecord record) {
         // default cache does not track record usage
     }
 
     @PreDestroy
     public void dispose() {
         flush();
     }
 }