package org.apache.maven.surefire.booter;
   
   /*
    * 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 javax.annotation.Nonnull;
  import java.io.File;
  import java.net.MalformedURLException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedHashSet;
  import java.util.List;
  
  import static java.io.File.pathSeparatorChar;
  
  /**
   * An ordered list of classpath elements with set behaviour
   *
   * A Classpath is immutable and thread safe.
   *
   * Immutable and thread safe
   *
   * @author Kristian Rosenvold
   */
  public final class Classpath implements Iterable<String>, Cloneable
  {
      private final List<String> unmodifiableElements;
  
      public static Classpath join( Classpath firstClasspath, Classpath secondClasspath )
      {
          LinkedHashSet<String> accumulated =  new LinkedHashSet<>();
          if ( firstClasspath != null )
          {
              firstClasspath.addTo( accumulated );
          }
          if ( secondClasspath != null )
          {
              secondClasspath.addTo( accumulated );
          }
          return new Classpath( accumulated );
      }
  
      private void addTo( @Nonnull Collection<String> c )
      {
          c.addAll( unmodifiableElements );
      }
  
      private Classpath()
      {
          unmodifiableElements = Collections.emptyList();
      }
  
      public Classpath( @Nonnull Classpath other, @Nonnull String additionalElement )
      {
          ArrayList<String> elems = new ArrayList<>( other.unmodifiableElements );
          elems.add( additionalElement );
          unmodifiableElements = Collections.unmodifiableList( elems );
      }
  
      public Classpath( @Nonnull Collection<String> elements )
      {
          List<String> newCp = new ArrayList<>( elements.size() );
          for ( String element : elements )
          {
              element = element.trim();
              if ( !element.isEmpty() )
              {
                  newCp.add( element );
              }
          }
          unmodifiableElements = Collections.unmodifiableList( newCp );
      }
  
      public static Classpath emptyClasspath()
      {
          return new Classpath();
      }
  
      public Classpath addClassPathElementUrl( String path )
      {
          if ( path == null )
         {
             throw new IllegalArgumentException( "Null is not a valid class path element url." );
         }
         return !unmodifiableElements.contains( path ) ? new Classpath( this, path ) : this;
     }
 
     @Nonnull
     public List<String> getClassPath()
     {
         return unmodifiableElements;
     }
 
     public void writeToSystemProperty( @Nonnull String propertyName )
     {
         StringBuilder sb = new StringBuilder();
         for ( String element : unmodifiableElements )
         {
             sb.append( element )
               .append( pathSeparatorChar );
         }
         System.setProperty( propertyName, sb.toString() );
     }
 
     @Override
     public boolean equals( Object o )
     {
         if ( this == o )
         {
             return true;
         }
         if ( o == null || getClass() != o.getClass() )
         {
             return false;
         }
 
         Classpath classpath = (Classpath) o;
 
         return unmodifiableElements.equals( classpath.unmodifiableElements );
     }
 
     public ClassLoader createClassLoader( boolean childDelegation, boolean enableAssertions, @Nonnull String roleName )
         throws SurefireExecutionException
     {
         try
         {
             ClassLoader parent = SystemUtils.platformClassLoader();
             IsolatedClassLoader classLoader = new IsolatedClassLoader( parent, childDelegation, roleName );
             for ( String classPathElement : unmodifiableElements )
             {
                 classLoader.addURL( new File( classPathElement ).toURL() );
             }
             if ( parent != null )
             {
                 parent.setDefaultAssertionStatus( enableAssertions );
             }
             classLoader.setDefaultAssertionStatus( enableAssertions );
             return classLoader;
         }
         catch ( MalformedURLException e )
         {
             throw new SurefireExecutionException( "When creating classloader", e );
         }
     }
 
     @Override
     public int hashCode()
     {
         return unmodifiableElements.hashCode();
     }
 
     public String getLogMessage( @Nonnull String descriptor )
     {
         StringBuilder result = new StringBuilder( descriptor );
         for ( String element : unmodifiableElements )
         {
             result.append( "  " )
                     .append( element );
         }
         return result.toString();
     }
 
     public String getCompactLogMessage( @Nonnull String descriptor )
     {
         StringBuilder result = new StringBuilder( descriptor );
         for ( String element : unmodifiableElements )
         {
             result.append( "  " );
             if ( element != null )
             {
                 int pos = element.lastIndexOf( File.separatorChar );
                 result.append( pos == -1 ? element : element.substring( pos + 1 ) );
             }
             else
             {
                 result.append( (String) null );
             }
         }
         return result.toString();
     }
 
     @Override
     public Iterator<String> iterator()
     {
         return unmodifiableElements.iterator();
     }
 
     @Override
     public Classpath clone()
     {
         return new Classpath( unmodifiableElements );
     }
 }