/*
    * 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
    *
    *      https://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.channels;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.MappedByteBuffer;
  import java.nio.channels.Channel;
  import java.nio.channels.FileChannel;
  import java.nio.channels.FileLock;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.WritableByteChannel;
  import java.util.Objects;
  
  import org.apache.commons.io.build.AbstractStreamBuilder;
  
  /**
   * Filters a {@link FileChannel}.
   * <p>
   * A {@code FilterFileChannel} wraps some other channel, which it uses as its basic source of data, possibly transforming the data along the way or providing
   * additional functionality. The class {@code FilterFileChannel} itself simply overrides methods of {@code FileChannel} with versions that pass all requests to
   * the wrapped channel. Subclasses of {@code FilterFileChannel} may of course override any methods declared or inherited by {@code FilterFileChannel}, and may
   * also provide additional fields and methods.
   * </p>
   * <p>
   * You construct s simple instance with the {@link FilterFileChannel#FilterFileChannel(FileChannel) channel constructor} and more advanced instances through the
   * {@link Builder}.
   * </p>
   *
   * @since 2.22.0
   */
  public class FilterFileChannel extends FileChannel {
  
      /**
       * Builds instances of {@link FilterFileChannel} for subclasses.
       *
       * @param <F> The {@link FilterFileChannel} type.
       * @param <C> The {@link Channel} type wrapped by the FilterChannel.
       * @param <B> The builder type.
       */
      public abstract static class AbstractBuilder<F extends FilterFileChannel, C extends FileChannel, B extends AbstractBuilder<F, C, B>>
              extends AbstractStreamBuilder<F, AbstractBuilder<F, C, B>> {
  
          /**
           * Constructs instance for subclasses.
           */
          protected AbstractBuilder() {
              // empty
          }
      }
  
      /**
       * Builds instances of {@link FilterFileChannel}.
       */
      public static class Builder extends AbstractBuilder<FilterFileChannel, FileChannel, Builder> {
  
          /**
           * Builds instances of {@link FilterChannel}.
           */
          protected Builder() {
              // empty
          }
  
          @Override
          public FilterFileChannel get() throws IOException {
              return new FilterFileChannel(this);
          }
      }
  
      /**
       * Creates a new {@link Builder}.
       *
       * @return a new {@link Builder}.
       */
      public static Builder forFilterFileChannel() {
          return new Builder();
      }
  
      final FileChannel fileChannel;
  
      private FilterFileChannel(final Builder builder) throws IOException {
          this.fileChannel = builder.getChannel(FileChannel.class);
      }
  
     /**
      * Constructs a new instance.
      *
      * @param fileChannel the file channel to wrap.
      */
     public FilterFileChannel(final FileChannel fileChannel) {
         this.fileChannel = Objects.requireNonNull(fileChannel, "fileChannel");
     }
 
     @Override
     public boolean equals(final Object o) {
         return fileChannel.equals(o);
     }
 
     @Override
     public void force(final boolean metaData) throws IOException {
         fileChannel.force(metaData);
     }
 
     @Override
     public int hashCode() {
         return fileChannel.hashCode();
     }
 
     @Override
     protected void implCloseChannel() throws IOException {
         fileChannel.close();
     }
 
     @Override
     public FileLock lock(final long position, final long size, final boolean shared) throws IOException {
         return fileChannel.lock(position, size, shared);
     }
 
     @Override
     public MappedByteBuffer map(final MapMode mode, final long position, final long size) throws IOException {
         return fileChannel.map(mode, position, size);
     }
 
     @Override
     public long position() throws IOException {
         return fileChannel.position();
     }
 
     @Override
     public FileChannel position(final long newPosition) throws IOException {
         return fileChannel.position(newPosition);
     }
 
     @Override
     public int read(final ByteBuffer dst) throws IOException {
         return fileChannel.read(dst);
     }
 
     @Override
     public int read(final ByteBuffer dst, final long position) throws IOException {
         return fileChannel.read(dst, position);
     }
 
     @Override
     public long read(final ByteBuffer[] dsts, final int offset, final int length) throws IOException {
         return fileChannel.read(dsts, offset, length);
     }
 
     @Override
     public long size() throws IOException {
         return fileChannel.size();
     }
 
     @Override
     public String toString() {
         return fileChannel.toString();
     }
 
     @Override
     public long transferFrom(final ReadableByteChannel src, final long position, final long count) throws IOException {
         return fileChannel.transferFrom(src, position, count);
     }
 
     @Override
     public long transferTo(final long position, final long count, final WritableByteChannel target) throws IOException {
         return fileChannel.transferTo(position, count, target);
     }
 
     @Override
     public FileChannel truncate(final long size) throws IOException {
         return fileChannel.truncate(size);
     }
 
     @Override
     public FileLock tryLock(final long position, final long size, final boolean shared) throws IOException {
         return fileChannel.tryLock(position, size, shared);
     }
 
     /**
      * Unwraps this instance by returning the underlying {@link FileChannel}.
      * <p>
      * Use with caution.
      * </p>
      *
      * @return the underlying {@link FileChannel}.
      */
     public FileChannel unwrap() {
         return fileChannel;
     }
 
     @Override
     public int write(final ByteBuffer src) throws IOException {
         return fileChannel.write(src);
     }
 
     @Override
     public int write(final ByteBuffer src, final long position) throws IOException {
         return fileChannel.write(src, position);
     }
 
     @Override
     public long write(final ByteBuffer[] srcs, final int offset, final int length) throws IOException {
         return fileChannel.write(srcs, offset, length);
     }
 }