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.spark.structuredstreaming.translation.batch;
  
  import static org.apache.beam.runners.spark.structuredstreaming.translation.utils.ScalaInterop.tuple;
  import static org.apache.beam.sdk.transforms.windowing.PaneInfo.NO_FIRING;
  import static org.apache.beam.sdk.transforms.windowing.TimestampCombiner.END_OF_WINDOW;
  
  import java.util.Collection;
  import org.apache.beam.runners.spark.structuredstreaming.translation.utils.ScalaInterop;
  import org.apache.beam.runners.spark.structuredstreaming.translation.utils.ScalaInterop.Fun1;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.GlobalWindows;
  import org.apache.beam.sdk.transforms.windowing.TimestampCombiner;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowedValues;
  import org.apache.beam.sdk.values.WindowingStrategy;
  import scala.Tuple2;
  import scala.collection.TraversableOnce;
  
  /**
   * Package private helpers to support translating grouping transforms using `groupByKey` such as
   * {@link GroupByKeyTranslatorBatch} or {@link CombinePerKeyTranslatorBatch}.
   */
  class GroupByKeyHelpers {
  
    private GroupByKeyHelpers() {}
  
    /**
     * Checks if it's possible to use an optimized `groupByKey` that also moves the window into the
     * key.
     *
     * @param windowing The windowing strategy
     * @param endOfWindowOnly Flag if to limit this optimization to {@link
     *     TimestampCombiner#END_OF_WINDOW}.
     */
    static boolean eligibleForGroupByWindow(
        WindowingStrategy<?, ?> windowing, boolean endOfWindowOnly) {
      return !windowing.needsMerge()
          && (!endOfWindowOnly || windowing.getTimestampCombiner() == END_OF_WINDOW)
          && windowing.getWindowFn().windowCoder().consistentWithEquals();
    }
  
    /**
     * Checks if it's possible to use an optimized `groupByKey` for the global window.
     *
     * @param windowing The windowing strategy
     * @param endOfWindowOnly Flag if to limit this optimization to {@link
     *     TimestampCombiner#END_OF_WINDOW}.
     */
    static boolean eligibleForGlobalGroupBy(
        WindowingStrategy<?, ?> windowing, boolean endOfWindowOnly) {
      return windowing.getWindowFn() instanceof GlobalWindows
          && (!endOfWindowOnly || windowing.getTimestampCombiner() == END_OF_WINDOW);
    }
  
    /**
     * Explodes a windowed {@link KV} assigned to potentially multiple {@link BoundedWindow}s to a
     * traversable of composite keys {@code (BoundedWindow, Key)} and value.
     */
    static <K, V, T>
        Fun1<WindowedValue<KV<K, V>>, TraversableOnce<Tuple2<Tuple2<BoundedWindow, K>, T>>>
            explodeWindowedKey(Fun1<WindowedValue<KV<K, V>>, T> valueFn) {
      return v -> {
        T value = valueFn.apply(v);
        K key = v.getValue().getKey();
        Collection<BoundedWindow> windows = (Collection<BoundedWindow>) v.getWindows();
        return ScalaInterop.scalaIterator(windows).map(w -> tuple(tuple(w, key), value));
      };
    }
  
    static <K, V> Fun1<Tuple2<Tuple2<BoundedWindow, K>, V>, WindowedValue<KV<K, V>>> windowedKV() {
      return t -> windowedKV(t._1, t._2);
    }
  
    static <K, V> WindowedValue<KV<K, V>> windowedKV(Tuple2<BoundedWindow, K> key, V value) {
      return WindowedValues.of(KV.of(key._2, value), key._1.maxTimestamp(), key._1, NO_FIRING);
    }
  
    static <V> Fun1<WindowedValue<V>, V> value() {
      return v -> v.getValue();
    }
  
    static <K, V> Fun1<WindowedValue<KV<K, V>>, V> valueValue() {
      return v -> v.getValue().getValue();
    }
  
    static <K, V> Fun1<WindowedValue<KV<K, V>>, K> valueKey() {
      return v -> v.getValue().getKey();
    }
  }
  