content: /*
   * 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.
   */
  package org.apache.asterix.external.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.file.FileVisitResult;
  import java.nio.file.Files;
  import java.nio.file.LinkOption;
  import java.nio.file.Path;
  import java.nio.file.SimpleFileVisitor;
  import java.nio.file.attribute.BasicFileAttributes;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.regex.Pattern;
  
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.common.exceptions.RuntimeDataException;
  
  public class LocalFileSystemUtils {
  
      public static void traverse(final List<File> files, File root, final String expression, final LinkedList<Path> dirs)
              throws IOException {
          final Path path = root.toPath();
          if (!Files.exists(path)) {
              throw new RuntimeDataException(ErrorCode.UTIL_LOCAL_FILE_SYSTEM_UTILS_PATH_NOT_FOUND, path.toString());
          }
          if (!Files.isDirectory(path)) {
              validateAndAdd(path, expression, files);
          }
          Files.walkFileTree(path, new SimpleFileVisitor<Path>() {
              @Override
              public FileVisitResult preVisitDirectory(Path path, BasicFileAttributes attrs) throws IOException {
                  if (!Files.exists(path, LinkOption.NOFOLLOW_LINKS)) {
                      return FileVisitResult.TERMINATE;
                  }
                  if (Files.isDirectory(path, LinkOption.NOFOLLOW_LINKS)) {
                      if (dirs != null) {
                          dirs.add(path);
                      }
                      //get immediate children files
                      File[] content = path.toFile().listFiles();
                      for (File file : content) {
                          if (!file.isDirectory()) {
                              validateAndAdd(file.toPath(), expression, files);
                          }
                      }
                  } else {
                      // Path is a file, add to list of files if it matches the expression
                      validateAndAdd(path, expression, files);
                  }
                  return FileVisitResult.CONTINUE;
              }
          });
      }
  
      private static boolean fileNotExistsInList(List<File> files, Path path) {
          for (File file : files) {
              if (file.getPath().equals(path.toString())) {
                  return false;
              }
          }
          return true;
      }
  
      public static void validateAndAdd(Path path, String expression, List<File> files) {
          if ((expression == null || Pattern.matches(expression, path.toString())) && fileNotExistsInList(files, path)) {
              files.add(new File(path.toString()));
          }
      }
  }
  