/*
    * 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.eclipse.aether.internal.impl.collect;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.artifact.ArtifactType;
  import org.eclipse.aether.artifact.ArtifactTypeRegistry;
  
  /**
   * A short-lived artifact type registry that caches results from a presumably slower type registry.
   * Internal helper class for collector implementations.
   */
  public class CachingArtifactTypeRegistry implements ArtifactTypeRegistry {
  
      private final ArtifactTypeRegistry delegate;
  
      private final Map<String, ArtifactType> types;
  
      public static ArtifactTypeRegistry newInstance(RepositorySystemSession session) {
          return newInstance(session.getArtifactTypeRegistry());
      }
  
      public static ArtifactTypeRegistry newInstance(ArtifactTypeRegistry delegate) {
          return (delegate != null) ? new CachingArtifactTypeRegistry(delegate) : null;
      }
  
      private CachingArtifactTypeRegistry(ArtifactTypeRegistry delegate) {
          this.delegate = delegate;
          types = new HashMap<>();
      }
  
      public ArtifactType get(String typeId) {
          ArtifactType type = types.get(typeId);
  
          if (type == null) {
              type = delegate.get(typeId);
              types.put(typeId, type);
          }
  
          return type;
      }
  }