package org.apache.maven.shared.runtime;

 /*

  * 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.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import java.net.URLConnection;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 import org.apache.maven.model.Model;

 import org.apache.maven.model.io.xpp3.MavenXpp3Reader;

 import org.apache.maven.project.DuplicateProjectException;

 import org.apache.maven.project.MavenProject;

 import org.apache.maven.project.ProjectSorter;

 import org.codehaus.plexus.util.IOUtil;

 import org.codehaus.plexus.util.ReaderFactory;

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

 import org.codehaus.plexus.util.xml.pull.XmlPullParserException;

 /**

  * A visitor that parses and collects Maven project XML files.

  * 

  * @author <a href="mailto:markh@apache.org">Mark Hobson</a>

  * @version $Id: XMLMavenRuntimeVisitor.java 1341416 2012-05-22 11:38:54Z markh $

  */

 class XMLMavenRuntimeVisitor implements MavenRuntimeVisitor

 {

     // fields -----------------------------------------------------------------

     /**

      * A list of the collected Maven projects.

      */

     private final List<MavenProject> projects;

     // constructors -----------------------------------------------------------

     /**

      * Creates a new {@code XMLMavenRuntimeVisitor}.

      */

     public XMLMavenRuntimeVisitor()

     {

         projects = new ArrayList<MavenProject>();

     }

     // MavenRuntimeVisitor methods --------------------------------------------

     /**

      * {@inheritDoc}

      */

     public void visitProjectProperties( URL url ) throws MavenRuntimeException

     {

         // no-op

     }

     /**

      * {@inheritDoc}

      */

     public void visitProjectXML( URL url ) throws MavenRuntimeException

     {

         MavenProject project = parseProjectXML( url );

         projects.add( project );

     }

     // public methods ---------------------------------------------------------

     /**

      * Gets the collected Maven projects.

      * 

      * @return an unmodifiable list of the collected Maven projects

      */

     public List<MavenProject> getProjects()

     {

         return Collections.unmodifiableList( projects );

     }

     /**

      * Gets the collected Maven projects ordered by dependencies.

      * 

      * @return an unmodifiable list of the collected Maven projects ordered by dependencies

      * @throws MavenRuntimeException

      *             if an error occurred ordering the projects

      */

     public List<MavenProject> getSortedProjects() throws MavenRuntimeException

     {

         // mediate dependency versions since declared versions can differ from runtime versions

         List<MavenProject> mediatedProjects = new ArrayList<MavenProject>( projects );

         MavenProjectUtils.mediateDependencyVersions( mediatedProjects );

         try

         {

             ProjectSorter projectSorter = new ProjectSorter( mediatedProjects );

             return genericList( projectSorter.getSortedProjects(), MavenProject.class );

         }

         catch ( CycleDetectedException exception )

         {

             throw new MavenRuntimeException( "Cannot sort projects", exception );

         }

         catch ( DuplicateProjectException exception )

         {

             throw new MavenRuntimeException( "Cannot sort projects", exception );

         }

     }

     // private methods --------------------------------------------------------

     /**

      * Parses the specified Maven project XML into a {@code MavenProject} object.

      * 

      * @param url

      *            a URL to the Maven project XML

      * @return a {@code MavenProject} object that represents the XML

      * @throws MavenRuntimeException

      *             if an error occurs parsing the XML

      */

     private MavenProject parseProjectXML( URL url ) throws MavenRuntimeException

     {

         MavenXpp3Reader reader = new MavenXpp3Reader();

         InputStream in = null;

         try

         {

             URLConnection connection = url.openConnection();

             connection.setUseCaches( false );

             in = connection.getInputStream();

             Model model = reader.read( ReaderFactory.newXmlReader( in ) );

             return new MavenProject( model );

         }

         catch ( XmlPullParserException exception )

         {

             throw new MavenRuntimeException( "Cannot read project XML: " + url, exception );

         }

         catch ( IOException exception )

         {

             throw new MavenRuntimeException( "Cannot read project XML: " + url, exception );

         }

         finally

         {

             IOUtil.close( in );

         }

     }

     /**

      * Converts the specified raw list to a generic list of a specified type by explicitly casting each element.

      * 

      * @param <T>

      *            the type of the required generic list

      * @param list

      *            the raw type

      * @param type

      *            the class that represents the type of the required generic list

      * @return the generic list

      */

     private static <T> List<T> genericList( List<?> list, Class<T> type )

     {

         List<T> genericList = new ArrayList<T>();

         for ( Object element : list )

         {

             genericList.add( type.cast( element ) );

         }

         return genericList;

     }

 }