/*
    * 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.logging.log4j.core.appender.rolling.action;
  
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.status.StatusLogger;
  
  import java.io.IOException;
  import java.nio.file.FileVisitResult;
  import java.nio.file.NoSuchFileException;
  import java.nio.file.Path;
  import java.nio.file.SimpleFileVisitor;
  import java.nio.file.attribute.BasicFileAttributes;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Objects;
  
  /**
   * FileVisitor that sorts files.
   */
  public class SortingVisitor extends SimpleFileVisitor<Path> {
  
      private static final Logger LOGGER = StatusLogger.getLogger();
      private final PathSorter sorter;
      private final List<PathWithAttributes> collected = new ArrayList<>();
  
      /**
       * Constructs a new DeletingVisitor.
       *
       * @param basePath used to relativize paths
       * @param pathFilters objects that need to confirm whether a file can be deleted
       */
      public SortingVisitor(final PathSorter sorter) {
          this.sorter = Objects.requireNonNull(sorter, "sorter");
      }
  
      @Override
      public FileVisitResult visitFile(final Path path, final BasicFileAttributes attrs) throws IOException {
          collected.add(new PathWithAttributes(path, attrs));
          return FileVisitResult.CONTINUE;
      }
  
      @Override
      public FileVisitResult visitFileFailed(Path file, IOException ioException) throws IOException {
          // LOG4J2-2677: Appenders may rollover and purge in parallel. SimpleVisitor rethrows exceptions from
          // failed attempts to load file attributes.
          if (ioException instanceof NoSuchFileException) {
              LOGGER.info("File {} could not be accessed, it has likely already been deleted", file, ioException);
              return FileVisitResult.CONTINUE;
          } else {
              return super.visitFileFailed(file, ioException);
          }
      }
  
      public List<PathWithAttributes> getSortedPaths() {
          Collections.sort(collected, sorter);
          return collected;
      }
  }