package org.apache.maven.plugin.surefire.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 org.apache.maven.surefire.testset.TestFilter;
  
  import java.io.File;
  import java.util.Collection;
  
  import static org.apache.maven.surefire.util.internal.StringUtils.isBlank;
  
  final class FileScanner
  {
      private final File basedir;
  
      private final String ext;
  
      FileScanner( File basedir, String ext )
      {
          this.basedir = basedir;
          ext = ext.trim();
          if ( isBlank( ext ) )
          {
              throw new IllegalArgumentException( "No file extension" );
          }
          this.ext = ext.startsWith( "." ) ? ext : "." + ext;
      }
  
      void scanTo( Collection<String> scannedJavaClassNames, TestFilter<String, String> filter )
      {
          scan( scannedJavaClassNames, filter, basedir );
      }
  
      private void scan( Collection<String> scannedJavaClassNames,
                         TestFilter<String, String> filter, File basedir, String... subDirectories )
      {
          File[] filesAndDirs = basedir.listFiles();
          if ( filesAndDirs != null )
          {
              final String pAckage = toJavaPackage( subDirectories );
              final String path = toPath( subDirectories );
              final String ext = this.ext;
              final boolean hasExtension = ext != null;
              final int extLength = hasExtension ? ext.length() : 0;
              for ( File fileOrDir : filesAndDirs )
              {
                  String name = fileOrDir.getName();
                  if ( !name.isEmpty() )
                  {
                      if ( fileOrDir.isFile() )
                      {
                          final int clsLength = name.length() - extLength;
                          if ( clsLength > 0
                              && ( !hasExtension || name.regionMatches( true, clsLength, ext, 0, extLength ) ) )
                          {
                              String simpleClassName = hasExtension ? name.substring( 0, clsLength ) : name;
                              if ( filter.shouldRun( toFile( path, simpleClassName ), null ) )
                              {
                                  String fullyQualifiedClassName =
                                      pAckage.isEmpty() ? simpleClassName : pAckage + '.' + simpleClassName;
                                  scannedJavaClassNames.add( fullyQualifiedClassName );
                              }
                          }
                      }
                      else if ( fileOrDir.isDirectory() )
                      {
                          String[] paths = new String[subDirectories.length + 1];
                          System.arraycopy( subDirectories, 0, paths, 0, subDirectories.length );
                          paths[subDirectories.length] = name;
                          scan( scannedJavaClassNames, filter, fileOrDir, paths );
                      }
                  }
              }
          }
      }
  
      private static String toJavaPackage( String... subDirectories )
      {
          StringBuilder pkg = new StringBuilder();
          for ( int i = 0; i < subDirectories.length; i++ )
          {
              if ( i > 0 && i < subDirectories.length )
             {
                 pkg.append( '.' );
             }
             pkg.append( subDirectories[i] );
         }
         return pkg.toString();
     }
 
     private static String toPath( String... subDirectories )
     {
         StringBuilder pkg = new StringBuilder();
         for ( int i = 0; i < subDirectories.length; i++ )
         {
             if ( i > 0 && i < subDirectories.length )
             {
                 pkg.append( '/' );
             }
             pkg.append( subDirectories[i] );
         }
         return pkg.toString();
     }
 
     private String toFile( String path, String fileNameWithoutExtension )
     {
         String pathWithoutExtension =
             path.isEmpty() ? fileNameWithoutExtension : path + '/' + fileNameWithoutExtension;
         return pathWithoutExtension + ext;
     }
 }