/*
 * 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.tsfile.external.commons.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.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Arrays;
import java.util.Objects;

/**
 * Deletes files and directories as a visit proceeds.
 *
 * @since 2.7
 */
public class DeletingPathVisitor extends CountingPathVisitor {

  private final String[] skip;
  private final boolean overrideReadOnly;
  private final LinkOption[] linkOptions;

  /**
   * Constructs a new visitor that deletes files except for the files and directories explicitly
   * given.
   *
   * @param pathCounter How to count visits.
   * @param deleteOption How deletion is handled.
   * @param skip The files to skip deleting.
   * @since 2.8.0
   */
  public DeletingPathVisitor(
      final Counters.PathCounters pathCounter,
      final DeleteOption[] deleteOption,
      final String... skip) {
    this(pathCounter, PathUtils.noFollowLinkOptionArray(), deleteOption, skip);
  }

  /**
   * Constructs a new visitor that deletes files except for the files and directories explicitly
   * given.
   *
   * @param pathCounter How to count visits.
   * @param linkOptions How symbolic links are handled.
   * @param deleteOption How deletion is handled.
   * @param skip The files to skip deleting.
   * @since 2.9.0
   */
  public DeletingPathVisitor(
      final Counters.PathCounters pathCounter,
      final LinkOption[] linkOptions,
      final DeleteOption[] deleteOption,
      final String... skip) {
    super(pathCounter);
    final String[] temp = skip != null ? skip.clone() : EMPTY_STRING_ARRAY;
    Arrays.sort(temp);
    this.skip = temp;
    this.overrideReadOnly = StandardDeleteOption.overrideReadOnly(deleteOption);
    // TODO Files.deleteIfExists() never follows links, so use LinkOption.NOFOLLOW_LINKS in other
    // calls to Files.
    this.linkOptions =
        linkOptions == null ? PathUtils.noFollowLinkOptionArray() : linkOptions.clone();
  }

  /**
   * Returns true to process the given path, false if not.
   *
   * @param path the path to test.
   * @return true to process the given path, false if not.
   */
  private boolean accept(final Path path) {
    return Arrays.binarySearch(skip, PathUtils.getFileNameString(path)) < 0;
  }

  @Override
  public boolean equals(final Object obj) {
    if (this == obj) {
      return true;
    }
    if (!super.equals(obj)) {
      return false;
    }
    if (getClass() != obj.getClass()) {
      return false;
    }
    final DeletingPathVisitor other = (DeletingPathVisitor) obj;
    return overrideReadOnly == other.overrideReadOnly && Arrays.equals(skip, other.skip);
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = super.hashCode();
    result = prime * result + Arrays.hashCode(skip);
    result = prime * result + Objects.hash(overrideReadOnly);
    return result;
  }

  @Override
  public FileVisitResult postVisitDirectory(final Path dir, final IOException exc)
      throws IOException {
    if (PathUtils.isEmptyDirectory(dir)) {
      Files.deleteIfExists(dir);
    }
    return super.postVisitDirectory(dir, exc);
  }

  @Override
  public FileVisitResult preVisitDirectory(final Path dir, final BasicFileAttributes attrs)
      throws IOException {
    super.preVisitDirectory(dir, attrs);
    return accept(dir) ? FileVisitResult.CONTINUE : FileVisitResult.SKIP_SUBTREE;
  }

  @Override
  public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs)
      throws IOException {
    if (accept(file)) {
      // delete files and valid links, respecting linkOptions
      if (Files.exists(file, linkOptions)) {
        if (overrideReadOnly) {
          PathUtils.setReadOnly(file, false, linkOptions);
        }
        Files.deleteIfExists(file);
      }
      // invalid links will survive previous delete, different approach needed:
      if (Files.isSymbolicLink(file)) {
        try {
          // deleteIfExists does not work for this case
          Files.delete(file);
        } catch (final NoSuchFileException ignored) {
          // ignore
        }
      }
    }
    updateFileCounters(file, attrs);
    return FileVisitResult.CONTINUE;
  }
}
