/*
    * 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.commons.io.file;
  
  import java.io.IOException;
  import java.math.BigInteger;
  import java.nio.file.FileVisitResult;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.attribute.BasicFileAttributes;
  import java.util.Objects;
  
  import org.apache.commons.io.file.Counters.PathCounters;
  import org.apache.commons.io.filefilter.IOFileFilter;
  import org.apache.commons.io.filefilter.SymbolicLinkFileFilter;
  import org.apache.commons.io.filefilter.TrueFileFilter;
  import org.apache.commons.io.function.IOBiFunction;
  
  /**
   * Counts files, directories, and sizes, as a visit proceeds.
   *
   * @since 2.7
   */
  public class CountingPathVisitor extends SimplePathVisitor {
  
      static final String[] EMPTY_STRING_ARRAY = {};
  
      static IOFileFilter defaultDirFilter() {
          return TrueFileFilter.INSTANCE;
      }
  
      static IOFileFilter defaultFileFilter() {
          return new SymbolicLinkFileFilter(FileVisitResult.TERMINATE, FileVisitResult.CONTINUE);
      }
  
      /**
       * Constructs a new instance configured with a {@link BigInteger} {@link PathCounters}.
       *
       * @return a new instance configured with a {@link BigInteger} {@link PathCounters}.
       */
      public static CountingPathVisitor withBigIntegerCounters() {
          return new CountingPathVisitor(Counters.bigIntegerPathCounters());
      }
  
      /**
       * Constructs a new instance configured with a {@code long} {@link PathCounters}.
       *
       * @return a new instance configured with a {@code long} {@link PathCounters}.
       */
      public static CountingPathVisitor withLongCounters() {
          return new CountingPathVisitor(Counters.longPathCounters());
      }
  
      private final PathCounters pathCounters;
      private final PathFilter fileFilter;
      private final PathFilter dirFilter;
  
      /**
       * Constructs a new instance.
       *
       * @param pathCounter How to count path visits.
       */
      public CountingPathVisitor(final PathCounters pathCounter) {
          this(pathCounter, defaultFileFilter(), defaultDirFilter());
      }
  
      /**
       * Constructs a new instance.
       *
       * @param pathCounter How to count path visits.
       * @param fileFilter Filters which files to count.
       * @param dirFilter Filters which directories to count.
       * @since 2.9.0
       */
      public CountingPathVisitor(final PathCounters pathCounter, final PathFilter fileFilter, final PathFilter dirFilter) {
          this.pathCounters = Objects.requireNonNull(pathCounter, "pathCounter");
          this.fileFilter = Objects.requireNonNull(fileFilter, "fileFilter");
          this.dirFilter = Objects.requireNonNull(dirFilter, "dirFilter");
      }
  
      /**
       * Constructs a new instance.
       *
       * @param pathCounter How to count path visits.
      * @param fileFilter Filters which files to count.
      * @param dirFilter Filters which directories to count.
      * @param visitFileFailed Called on {@link #visitFileFailed(Path, IOException)}.
      * @since 2.12.0
      */
     public CountingPathVisitor(final PathCounters pathCounter, final PathFilter fileFilter, final PathFilter dirFilter,
         final IOBiFunction<Path, IOException, FileVisitResult> visitFileFailed) {
         super(visitFileFailed);
         this.pathCounters = Objects.requireNonNull(pathCounter, "pathCounter");
         this.fileFilter = Objects.requireNonNull(fileFilter, "fileFilter");
         this.dirFilter = Objects.requireNonNull(dirFilter, "dirFilter");
     }
 
     @Override
     public boolean equals(final Object obj) {
         if (this == obj) {
             return true;
         }
         if (!(obj instanceof CountingPathVisitor)) {
             return false;
         }
         final CountingPathVisitor other = (CountingPathVisitor) obj;
         return Objects.equals(pathCounters, other.pathCounters);
     }
 
     /**
      * Gets the visitation counts.
      *
      * @return the visitation counts.
      */
     public PathCounters getPathCounters() {
         return pathCounters;
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(pathCounters);
     }
 
     @Override
     public FileVisitResult postVisitDirectory(final Path dir, final IOException exc) throws IOException {
         updateDirCounter(dir, exc);
         return FileVisitResult.CONTINUE;
     }
 
     @Override
     public FileVisitResult preVisitDirectory(final Path dir, final BasicFileAttributes attributes) throws IOException {
         final FileVisitResult accept = dirFilter.accept(dir, attributes);
         return accept != FileVisitResult.CONTINUE ? FileVisitResult.SKIP_SUBTREE : FileVisitResult.CONTINUE;
     }
 
     @Override
     public String toString() {
         return pathCounters.toString();
     }
 
     /**
      * Updates the counter for visiting the given directory.
      *
      * @param dir the visited directory.
      * @param exc Encountered exception.
      * @since 2.9.0
      */
     protected void updateDirCounter(final Path dir, final IOException exc) {
         pathCounters.getDirectoryCounter().increment();
     }
 
     /**
      * Updates the counters for visiting the given file.
      *
      * @param file the visited file.
      * @param attributes the visited file attributes.
      */
     protected void updateFileCounters(final Path file, final BasicFileAttributes attributes) {
         pathCounters.getFileCounter().increment();
         pathCounters.getByteCounter().add(attributes.size());
     }
 
     @Override
     public FileVisitResult visitFile(final Path file, final BasicFileAttributes attributes) throws IOException {
         // Note: A file can be a symbolic link to a directory.
         if (Files.exists(file) && fileFilter.accept(file, attributes) == FileVisitResult.CONTINUE) {
             updateFileCounters(file, attributes);
         }
         return FileVisitResult.CONTINUE;
     }
 
 }