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.runners.flink.translation.types;
  
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.util.CoderUtils;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.primitives.Bytes;
  import org.apache.flink.api.common.typeinfo.TypeInformation;
  import org.apache.flink.api.java.functions.KeySelector;
  import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
  
  /**
   * {@link KeySelector} that extracts the key from a {@link KV} and returns it in encoded form as a
   * {@code byte} array.
   */
  public class WindowedKvKeySelector<InputT, K>
      implements KeySelector<WindowedValue<KV<K, InputT>>, byte[]>, ResultTypeQueryable<byte[]> {
  
    private final Coder<K> keyCoder;
    private final Coder<? extends BoundedWindow> windowCoder;
  
    public WindowedKvKeySelector(Coder<K> keyCoder, Coder<? extends BoundedWindow> windowCoder) {
      this.keyCoder = keyCoder;
      this.windowCoder = windowCoder;
    }
  
    @Override
    public byte[] getKey(WindowedValue<KV<K, InputT>> value) throws Exception {
      final byte[] encodedKey = CoderUtils.encodeToByteArray(keyCoder, value.getValue().getKey());
      @SuppressWarnings("unchecked")
      final byte[] encodedWindow =
          CoderUtils.encodeToByteArray(
              (Coder) windowCoder, Iterables.getOnlyElement(value.getWindows()));
      return Bytes.concat(encodedKey, encodedWindow);
    }
  
    @Override
    public TypeInformation<byte[]> getProducedType() {
      return new EncodedValueTypeInformation();
    }
  }
  