/*
 * 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.solr.morphlines.solr;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.file.Files;


class FileUtils {

  //-----------------------------------------------------------------------
  /**
   * Deletes a directory recursively. 
   *
   * @param directory  directory to delete
   * @throws IOException in case deletion is unsuccessful
   */
  public static void deleteDirectory(File directory) throws IOException {
      if (!directory.exists()) {
          return;
      }

      if (!isSymlink(directory)) {
          cleanDirectory(directory);
      }

      Files.delete(directory.toPath());
  }

  /**
   * Determines whether the specified file is a Symbolic Link rather than an actual file.
   * <p>
   * Will not return true if there is a Symbolic Link anywhere in the path,
   * only if the specific file is.
   *
   * @param file the file to check
   * @return true if the file is a Symbolic Link
   * @throws IOException if an IO error occurs while checking the file
   * @since Commons IO 2.0
   */
  public static boolean isSymlink(File file) throws IOException {
      if (file == null) {
          throw new NullPointerException("File must not be null");
      }
//      if (FilenameUtils.isSystemWindows()) {
      if (File.separatorChar == '\\') {
          return false;
      }
      File fileInCanonicalDir = null;
      if (file.getParent() == null) {
          fileInCanonicalDir = file;
      } else {
          File canonicalDir = file.getParentFile().getCanonicalFile();
          fileInCanonicalDir = new File(canonicalDir, file.getName());
      }
      
      if (fileInCanonicalDir.getCanonicalFile().equals(fileInCanonicalDir.getAbsoluteFile())) {
          return false;
      } else {
          return true;
      }
  }

  /**
   * Cleans a directory without deleting it.
   *
   * @param directory directory to clean
   * @throws IOException in case cleaning is unsuccessful
   */
  public static void cleanDirectory(File directory) throws IOException {
      if (!directory.exists()) {
          String message = directory + " does not exist";
          throw new IllegalArgumentException(message);
      }

      if (!directory.isDirectory()) {
          String message = directory + " is not a directory";
          throw new IllegalArgumentException(message);
      }

      File[] files = directory.listFiles();
      if (files == null) {  // null if security restricted
          throw new IOException("Failed to list contents of " + directory);
      }

      IOException exception = null;
      for (File file : files) {
          try {
              forceDelete(file);
          } catch (IOException ioe) {
              exception = ioe;
          }
      }

      if (null != exception) {
          throw exception;
      }
  }
  
  //-----------------------------------------------------------------------
  /**
   * Deletes a file. If file is a directory, delete it and all sub-directories.
   * <p>
   * The difference between File.delete() and this method are:
   * <ul>
   * <li>A directory to be deleted does not have to be empty.</li>
   * <li>You get exceptions when a file or directory cannot be deleted.
   *      (java.io.File methods returns a boolean)</li>
   * </ul>
   *
   * @param file  file or directory to delete, must not be <code>null</code>
   * @throws NullPointerException if the directory is <code>null</code>
   * @throws FileNotFoundException if the file was not found
   * @throws IOException in case deletion is unsuccessful
   */
  public static void forceDelete(File file) throws IOException {
      if (file.isDirectory()) {
          deleteDirectory(file);
      } else {
          Files.delete(file.toPath());
      }
  }

}