/*
    * 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 java.util.function.UnaryOperator;
  
  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 {
  
      /**
       * Builds instances of {@link CountingPathVisitor}.
       *
       * @param <T> The CountingPathVisitor type.
       * @param <B> The AbstractBuilder type.
       * @since 2.19.0
       */
      public abstract static class AbstractBuilder<T, B extends AbstractBuilder<T, B>> extends SimplePathVisitor.AbstractBuilder<T, B> {
  
          private PathCounters pathCounters = defaultPathCounters();
          private PathFilter fileFilter = defaultFileFilter();
          private PathFilter directoryFilter = defaultDirectoryFilter();
          private UnaryOperator<Path> directoryPostTransformer = defaultDirectoryTransformer();
  
          /**
           * Constructs a new builder for subclasses.
           */
          public AbstractBuilder() {
              // empty.
          }
  
          PathFilter getDirectoryFilter() {
              return directoryFilter;
          }
  
          UnaryOperator<Path> getDirectoryPostTransformer() {
              return directoryPostTransformer;
          }
  
          PathFilter getFileFilter() {
              return fileFilter;
          }
  
          PathCounters getPathCounters() {
              return pathCounters;
          }
  
          /**
           * Sets how to filter directories.
           *
           * @param directoryFilter how to filter files.
           * @return this instance.
           */
          public B setDirectoryFilter(final PathFilter directoryFilter) {
              this.directoryFilter = directoryFilter != null ? directoryFilter : defaultDirectoryFilter();
              return asThis();
          }
  
          /**
           * Sets how to transform directories, defaults to {@link UnaryOperator#identity()}.
           *
           * @param directoryTransformer how to filter files.
           * @return this instance.
           */
          public B setDirectoryPostTransformer(final UnaryOperator<Path> directoryTransformer) {
              this.directoryPostTransformer = directoryTransformer != null ? directoryTransformer : defaultDirectoryTransformer();
              return asThis();
          }
 
         /**
          * Sets how to filter files.
          *
          * @param fileFilter how to filter files.
          * @return this instance.
          */
         public B setFileFilter(final PathFilter fileFilter) {
             this.fileFilter = fileFilter != null ? fileFilter : defaultFileFilter();
             return asThis();
         }
 
         /**
          * Sets how to count path visits.
          *
          * @param pathCounters How to count path visits.
          * @return this instance.
          */
         public B setPathCounters(final PathCounters pathCounters) {
             this.pathCounters = pathCounters != null ? pathCounters : defaultPathCounters();
             return asThis();
         }
     }
 
     /**
      * Builds instances of {@link CountingPathVisitor}.
      *
      * @since 2.18.0
      */
     public static class Builder extends AbstractBuilder<CountingPathVisitor, Builder> {
 
         /**
          * Constructs a new builder.
          */
         public Builder() {
             // empty.
         }
 
         @Override
         public CountingPathVisitor get() {
             return new CountingPathVisitor(this);
         }
     }
 
     static final String[] EMPTY_STRING_ARRAY = {};
 
     static IOFileFilter defaultDirectoryFilter() {
         return TrueFileFilter.INSTANCE;
     }
 
     static UnaryOperator<Path> defaultDirectoryTransformer() {
         return UnaryOperator.identity();
     }
 
     static IOFileFilter defaultFileFilter() {
         return new SymbolicLinkFileFilter(FileVisitResult.TERMINATE, FileVisitResult.CONTINUE);
     }
 
     static PathCounters defaultPathCounters() {
         return Counters.longPathCounters();
     }
 
     /**
      * 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 Builder().setPathCounters(Counters.bigIntegerPathCounters()).get();
     }
 
     /**
      * 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 Builder().setPathCounters(Counters.longPathCounters()).get();
     }
 
     private final PathCounters pathCounters;
     private final PathFilter fileFilter;
     private final PathFilter directoryFilter;
     private final UnaryOperator<Path> directoryPostTransformer;
 
     CountingPathVisitor(final AbstractBuilder<?, ?> builder) {
         super(builder);
         this.pathCounters = builder.getPathCounters();
         this.fileFilter = builder.getFileFilter();
         this.directoryFilter = builder.getDirectoryFilter();
         this.directoryPostTransformer = builder.getDirectoryPostTransformer();
     }
 
     /**
      * Constructs a new instance.
      *
      * @param pathCounters How to count path visits.
      * @see Builder
      */
     public CountingPathVisitor(final PathCounters pathCounters) {
         this(new Builder().setPathCounters(pathCounters));
     }
 
     /**
      * Constructs a new instance.
      *
      * @param pathCounters    How to count path visits.
      * @param fileFilter      Filters which files to count.
      * @param directoryFilter Filters which directories to count.
      * @see Builder
      * @since 2.9.0
      */
     public CountingPathVisitor(final PathCounters pathCounters, final PathFilter fileFilter, final PathFilter directoryFilter) {
         this.pathCounters = Objects.requireNonNull(pathCounters, "pathCounters");
         this.fileFilter = Objects.requireNonNull(fileFilter, "fileFilter");
         this.directoryFilter = Objects.requireNonNull(directoryFilter, "directoryFilter");
         this.directoryPostTransformer = UnaryOperator.identity();
     }
 
     /**
      * Constructs a new instance.
      *
      * @param pathCounters    How to count path visits.
      * @param fileFilter      Filters which files to count.
      * @param directoryFilter Filters which directories to count.
      * @param visitFileFailed Called on {@link #visitFileFailed(Path, IOException)}.
      * @since 2.12.0
      * @deprecated Use {@link Builder}.
      */
     @Deprecated
     public CountingPathVisitor(final PathCounters pathCounters, final PathFilter fileFilter, final PathFilter directoryFilter,
             final IOBiFunction<Path, IOException, FileVisitResult> visitFileFailed) {
         super(visitFileFailed);
         this.pathCounters = Objects.requireNonNull(pathCounters, "pathCounters");
         this.fileFilter = Objects.requireNonNull(fileFilter, "fileFilter");
         this.directoryFilter = Objects.requireNonNull(directoryFilter, "directoryFilter");
         this.directoryPostTransformer = UnaryOperator.identity();
     }
 
     @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(directoryPostTransformer.apply(dir), exc);
         return FileVisitResult.CONTINUE;
     }
 
     @Override
     public FileVisitResult preVisitDirectory(final Path dir, final BasicFileAttributes attributes) throws IOException {
         final FileVisitResult accept = directoryFilter.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;
     }
 }