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.coders;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.List;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.util.common.ElementByteSizeObserver;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
  
  /**
   * A {@link TimestampPrefixingWindowCoder} wraps arbitrary user custom window coder. While encoding
   * the custom window type, it extracts the maxTimestamp(inclusive) of the window and prefix it to
   * the encoded bytes of the window using the user custom window coder.
   *
   * @param <T> The custom window type.
   */
  public class TimestampPrefixingWindowCoder<T extends BoundedWindow> extends StructuredCoder<T> {
    private final Coder<T> windowCoder;
  
    public static <T extends BoundedWindow> TimestampPrefixingWindowCoder<T> of(
        Coder<T> windowCoder) {
      return new TimestampPrefixingWindowCoder<>(windowCoder);
    }
  
    TimestampPrefixingWindowCoder(Coder<T> windowCoder) {
      this.windowCoder = windowCoder;
    }
  
    public Coder<T> getWindowCoder() {
      return windowCoder;
    }
  
    @Override
    public void encode(T value, OutputStream outStream) throws CoderException, IOException {
      if (value == null) {
        throw new CoderException("Cannot encode null window");
      }
      InstantCoder.of().encode(value.maxTimestamp(), outStream);
      windowCoder.encode(value, outStream);
    }
  
    @Override
    public T decode(InputStream inStream) throws CoderException, IOException {
      InstantCoder.of().decode(inStream);
      return windowCoder.decode(inStream);
    }
  
    @Override
    public List<? extends Coder<?>> getCoderArguments() {
      return Lists.newArrayList(windowCoder);
    }
  
    @Override
    public void verifyDeterministic() throws NonDeterministicException {
      windowCoder.verifyDeterministic();
    }
  
    @Override
    public boolean consistentWithEquals() {
      return windowCoder.consistentWithEquals();
    }
  
    @Override
    public boolean isRegisterByteSizeObserverCheap(T value) {
      return windowCoder.isRegisterByteSizeObserverCheap(value);
    }
  
    @Override
    public void registerByteSizeObserver(T value, ElementByteSizeObserver observer) throws Exception {
      InstantCoder.of().registerByteSizeObserver(value.maxTimestamp(), observer);
      windowCoder.registerByteSizeObserver(value, observer);
    }
  }
  