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 java.util.Collection;
  import org.apache.beam.runners.spark.structuredstreaming.translation.TransformTranslator;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.GlobalWindows;
  import org.apache.beam.sdk.transforms.windowing.Window;
  import org.apache.beam.sdk.transforms.windowing.WindowFn;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowedValues;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  import org.apache.spark.api.java.function.MapFunction;
  import org.apache.spark.sql.Dataset;
  import org.checkerframework.checker.nullness.qual.NonNull;
  import org.joda.time.Instant;
  
  class WindowAssignTranslatorBatch<T>
      extends TransformTranslator<PCollection<T>, PCollection<T>, Window.Assign<T>> {
  
    WindowAssignTranslatorBatch() {
      super(0.05f);
    }
  
    @Override
    public void translate(Window.Assign<T> transform, Context cxt) {
      WindowFn<T, ?> windowFn = transform.getWindowFn();
      PCollection<T> input = cxt.getInput();
      Dataset<WindowedValue<T>> inputDataset = cxt.getDataset(input);
  
      if (windowFn == null || skipAssignWindows(windowFn, input)) {
        cxt.putDataset(cxt.getOutput(), inputDataset);
      } else {
        Dataset<WindowedValue<T>> outputDataset =
            inputDataset.map(
                assignWindows(windowFn),
                cxt.windowedEncoder(input.getCoder(), windowFn.windowCoder()));
  
        cxt.putDataset(cxt.getOutput(), outputDataset);
      }
    }
  
    /**
     * Checks if the window transformation should be applied or skipped.
     *
     * <p>Avoid running assign windows if both source and destination are global window or if the user
     * has not specified the WindowFn (meaning they are just messing with triggering or allowed
     * lateness).
     */
    private boolean skipAssignWindows(WindowFn<T, ?> newFn, PCollection<T> input) {
      WindowFn<?, ?> currentFn = input.getWindowingStrategy().getWindowFn();
      return currentFn instanceof GlobalWindows && newFn instanceof GlobalWindows;
    }
  
    private static <T, W extends @NonNull BoundedWindow>
        MapFunction<WindowedValue<T>, WindowedValue<T>> assignWindows(WindowFn<T, W> windowFn) {
      return value -> {
        final BoundedWindow window = getOnlyWindow(value);
        final T element = value.getValue();
        final Instant timestamp = value.getTimestamp();
        Collection<W> windows =
            windowFn.assignWindows(
                windowFn.new AssignContext() {
  
                  @Override
                  public T element() {
                    return element;
                  }
  
                  @Override
                  public @NonNull Instant timestamp() {
                    return timestamp;
                  }
  
                  @Override
                  public @NonNull BoundedWindow window() {
                    return window;
                  }
                });
        return WindowedValues.of(element, timestamp, windows, value.getPaneInfo());
      };
    }
  
    private static <T> BoundedWindow getOnlyWindow(WindowedValue<T> wv) {
      return Iterables.getOnlyElement((Iterable<BoundedWindow>) wv.getWindows());
    }
  }
  