package org.apache.maven.project;
   
   /*
    * 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 java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  
  import org.apache.maven.model.Model;
  
  /**
   * Holds all Models that are known to the reactor. This allows the project builder to resolve imported Models from the
   * reactor when building another project's effective model.
   *
   * @author Benjamin Bentmann
   * @author Robert Scholte
   */
  class ReactorModelPool
  {
      private final Map<GAKey, Set<Model>> modelsByGa = new HashMap<>();
  
      private final Map<Path, Model> modelsByPath = new HashMap<>();
  
      /**
       * Get the model by its GAV or (since 4.0.0) by its GA if there is only one.
       *
       * @param groupId never {@code null}
       * @param artifactId never {@code null}
       * @param version can be {@code null}
       * @return the matching model or {@code null}
       * @throws IllegalStateException if version was null and multiple modules share the same groupId + artifactId
       */
      public Model get( String groupId, String artifactId, String version )
      {
          return modelsByGa.getOrDefault( new GAKey( groupId, artifactId ), Collections.emptySet() ).stream()
                          .filter( m -> version == null || version.equals( getVersion( m ) ) )
                          .reduce( ( a, b ) ->
                          {
                              throw new IllegalStateException( "Multiple modules with key "
                                  + a.getGroupId() + ':' + a.getArtifactId() );
                          } ).orElse( null );
      }
  
      /**
       * Find model by path, useful when location the parent by relativePath
       *
       * @param path
       * @return the matching model or {@code null}
       * @since 4.0.0
       */
      public Model get( Path path )
      {
          final Path pomFile;
          if ( Files.isDirectory( path ) )
          {
              pomFile = path.resolve( "pom.xml" );
          }
          else
          {
              pomFile = path;
          }
          return modelsByPath.get( pomFile );
      }
  
      private String getVersion( Model model )
      {
          String version = model.getVersion();
          if ( version == null && model.getParent() != null )
          {
              version = model.getParent().getVersion();
          }
          return version;
      }
  
      static class Builder
      {
          private ReactorModelPool pool = new ReactorModelPool();
 
         Builder put( Path pomFile, Model model )
         {
             pool.modelsByPath.put( pomFile, model );
             pool.modelsByGa.computeIfAbsent( new GAKey( getGroupId( model ), model.getArtifactId() ),
                                              k -> new HashSet<Model>() ).add( model );
             return this;
         }
 
         ReactorModelPool build()
         {
             return pool;
         }
 
         private static String getGroupId( Model model )
         {
             String groupId = model.getGroupId();
             if ( groupId == null && model.getParent() != null )
             {
                 groupId = model.getParent().getGroupId();
             }
             return groupId;
         }
     }
 
     private static final class GAKey
     {
 
         private final String groupId;
 
         private final String artifactId;
 
         private final int hashCode;
 
         GAKey( String groupId, String artifactId )
         {
             this.groupId = ( groupId != null ) ? groupId : "";
             this.artifactId = ( artifactId != null ) ? artifactId : "";
 
             hashCode = Objects.hash( this.groupId, this.artifactId );
         }
 
         @Override
         public boolean equals( Object obj )
         {
             if ( this == obj )
             {
                 return true;
             }
 
             GAKey that = (GAKey) obj;
 
             return artifactId.equals( that.artifactId ) && groupId.equals( that.groupId );
         }
 
         @Override
         public int hashCode()
         {
             return hashCode;
         }
 
         @Override
         public String toString()
         {
             StringBuilder buffer = new StringBuilder( 128 );
             buffer.append( groupId ).append( ':' ).append( artifactId );
             return buffer.toString();
         }
     }
 
 }