content: /*
   * 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.beam.sdk.extensions.gcp.util.channels;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.SeekableByteChannel;
  import java.nio.channels.WritableByteChannel;
  import java.util.Optional;
  import java.util.function.Consumer;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  public class CountingSeekableByteChannel implements SeekableByteChannel {
    private final SeekableByteChannel delegate;
    private final WritableByteChannel writableDelegate;
    private final ReadableByteChannel readableDelegate;
  
    public static CountingSeekableByteChannel createWithBytesReadConsumer(
        SeekableByteChannel delegate, Consumer<Integer> bytesReadConsumer) {
      return new CountingSeekableByteChannel(delegate, bytesReadConsumer, null);
    }
  
    public static CountingSeekableByteChannel createWithBytesWrittenConsumer(
        SeekableByteChannel delegate, Consumer<Integer> bytesWrittenConsumer) {
      return new CountingSeekableByteChannel(delegate, null, bytesWrittenConsumer);
    }
  
    // since it's equivalent to directly using the delegate, there's no point in using this variant
    // elsewhere than in tests
    @VisibleForTesting
    public static CountingSeekableByteChannel createWithNoOpConsumer(SeekableByteChannel delegate) {
      Consumer<Integer> noop = __ -> {};
      return new CountingSeekableByteChannel(delegate, noop, noop);
    }
  
    public CountingSeekableByteChannel(
        SeekableByteChannel delegate,
        @Nullable Consumer<Integer> bytesReadConsumer,
        @Nullable Consumer<Integer> bytesWrittenConsumer) {
  
      this.delegate = Preconditions.checkNotNull(delegate);
      Preconditions.checkArgument(
          bytesReadConsumer != null || bytesWrittenConsumer != null,
          "At least one of bytesReadConsumer or bytesWrittenConsumer must be non-null");
      this.readableDelegate =
          Optional.ofNullable(bytesReadConsumer)
              .<ReadableByteChannel>map(
                  consumer -> new CountingReadableByteChannel(delegate, consumer))
              .orElse(delegate);
      this.writableDelegate =
          Optional.ofNullable(bytesWrittenConsumer)
              .<WritableByteChannel>map(
                  consumer -> new CountingWritableByteChannel(delegate, consumer))
              .orElse(delegate);
    }
  
    @Override
    public int read(ByteBuffer dst) throws IOException {
      return readableDelegate.read(dst);
    }
  
    @Override
    public int write(ByteBuffer src) throws IOException {
      return writableDelegate.write(src);
    }
  
    @Override
    public long position() throws IOException {
      return delegate.position();
    }
  
    @Override
    public SeekableByteChannel position(long newPosition) throws IOException {
      delegate.position(newPosition);
      return this;
    }
  
    @Override
    public long size() throws IOException {
      return delegate.size();
    }
  
    @Override
    public SeekableByteChannel truncate(long size) throws IOException {
      delegate.truncate(size);
      return this;
    }
  
    @Override
    public boolean isOpen() {
      return delegate.isOpen();
    }
  
    @Override
    public void close() throws IOException {
      delegate.close();
    }
  }
  