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.net.URL;
  import java.util.List;
  
  import org.apache.maven.project.MavenProject;
  
  /**
   * Default implementation of {@code MavenRuntime}.
   * 
   * @author <a href="mailto:markh@apache.org">Mark Hobson</a>
   * @version $Id: DefaultMavenRuntime.java 831910 2009-11-02 15:05:33Z markh $
   * @see MavenRuntime
   * @plexus.component role="org.apache.maven.shared.runtime.MavenRuntime"
   */
  public class DefaultMavenRuntime implements MavenRuntime
  {
      // MavenRuntime methods ---------------------------------------------------
  
      /**
       * {@inheritDoc}
       */
      public MavenProjectProperties getProjectProperties( URL url ) throws MavenRuntimeException
      {
          PropertiesMavenRuntimeVisitor visitor = new PropertiesMavenRuntimeVisitor();
  
          MavenRuntimeVisitorUtils.accept( url, visitor );
  
          return first( visitor.getProjects() );
      }
  
      /**
       * {@inheritDoc}
       */
      public MavenProjectProperties getProjectProperties( Class<?> klass ) throws MavenRuntimeException
      {
          PropertiesMavenRuntimeVisitor visitor = new PropertiesMavenRuntimeVisitor();
  
          MavenRuntimeVisitorUtils.accept( klass, visitor );
  
          return first( visitor.getProjects() );
      }
  
      /**
       * {@inheritDoc}
       */
      public List<MavenProjectProperties> getProjectsProperties( ClassLoader classLoader ) throws MavenRuntimeException
      {
          PropertiesMavenRuntimeVisitor visitor = new PropertiesMavenRuntimeVisitor();
  
          MavenRuntimeVisitorUtils.accept( classLoader, visitor );
  
          return visitor.getProjects();
      }
      
      /**
       * {@inheritDoc}
       */
      public MavenProject getProject( URL url ) throws MavenRuntimeException
      {
          XMLMavenRuntimeVisitor visitor = new XMLMavenRuntimeVisitor();
          
          MavenRuntimeVisitorUtils.accept( url, visitor );
          
          return first( visitor.getProjects() );
      }
  
      /**
       * {@inheritDoc}
       */
      public MavenProject getProject( Class<?> klass ) throws MavenRuntimeException
      {
          XMLMavenRuntimeVisitor visitor = new XMLMavenRuntimeVisitor();
  
          MavenRuntimeVisitorUtils.accept( klass, visitor );
  
          return first( visitor.getProjects() );
      }
  
      /**
      * {@inheritDoc}
      */
     public List<MavenProject> getProjects( ClassLoader classLoader ) throws MavenRuntimeException
     {
         XMLMavenRuntimeVisitor visitor = new XMLMavenRuntimeVisitor();
 
         MavenRuntimeVisitorUtils.accept( classLoader, visitor );
 
         return visitor.getProjects();
     }
 
     /**
      * {@inheritDoc}
      */
     public List<MavenProject> getSortedProjects( ClassLoader classLoader ) throws MavenRuntimeException
     {
         XMLMavenRuntimeVisitor visitor = new XMLMavenRuntimeVisitor();
 
         MavenRuntimeVisitorUtils.accept( classLoader, visitor );
 
         return visitor.getSortedProjects();
     }
 
     // private methods --------------------------------------------------------
 
     /**
      * Gets the first element in the specified list or {@code null} if it is empty.
      * 
      * @param <T>
      *            the type of the specified list
      * @param list
      *            the list to examine
      * @return the first item in the list, or {@code null} if it is empty
      */
     private static <T> T first( List<T> list )
     {
         return !list.isEmpty() ? list.get( 0 ) : null;
     }
 }