package org.apache.maven.index.util;

 /*

  * 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.util.ArrayList;

 import java.util.HashMap;

 import java.util.List;

 import org.apache.maven.index.context.IndexCreator;

 import org.codehaus.plexus.util.dag.CycleDetectedException;

 import org.codehaus.plexus.util.dag.DAG;

 import org.codehaus.plexus.util.dag.TopologicalSorter;

 public class IndexCreatorSorter

 {

     public static List<IndexCreator> sort( List<? extends IndexCreator> creators )

         throws IllegalArgumentException

     {

         try

         {

             final HashMap<String, IndexCreator> creatorsById = new HashMap<String, IndexCreator>( creators.size() );

             DAG dag = new DAG();

             for ( IndexCreator creator : creators )

             {

                 creatorsById.put( creator.getId(), creator );

                 dag.addVertex( creator.getId() );

                 for ( String depId : creator.getCreatorDependencies() )

                 {

                     dag.addEdge( creator.getId(), depId );

                 }

             }

             List<String> sortedIds = TopologicalSorter.sort( dag );

             final ArrayList<IndexCreator> sortedCreators = new ArrayList<IndexCreator>( creators.size() );

             for ( String id : sortedIds )

             {

                 final IndexCreator creator = creatorsById.get( id );

                 if ( creator != null )

                 {

                     sortedCreators.add( creator );

                 }

                 else

                 {

                     throw new IllegalArgumentException( String.format(

                         "IndexCreator with ID=\"%s\" does not exists, the present creator ID=\"%s\" depends on it!",

                         id, dag.getParentLabels( id ) ) );

                 }

             }

             return sortedCreators;

         }

         catch ( CycleDetectedException e )

         {

             throw new IllegalArgumentException( "Supplied IndexCreator inter-dependencies", e );

         }

     }

 }