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.testing;
  
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.transforms.SimpleFunction;
  import org.apache.beam.sdk.transforms.windowing.PaneInfo;
  import org.apache.beam.sdk.transforms.windowing.PaneInfo.Timing;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.apache.beam.sdk.values.ValueInSingleWindow;
  
  /**
   * {@link PTransform PTransforms} which take an {@link Iterable} of {@link ValueInSingleWindow
   * ValueInSingleWindows} and outputs an {@link Iterable} of all values in the specified pane,
   * dropping the {@link ValueInSingleWindow} metadata.
   *
   * <p>Although all of the method signatures return SimpleFunction, users should ensure to set the
   * coder of any output {@link PCollection}, as appropriate {@link TypeDescriptor TypeDescriptors}
   * cannot be obtained when the extractor is created.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  final class PaneExtractors {
    private PaneExtractors() {}
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> onlyPane(
        PAssert.PAssertionSite site) {
      return new ExtractOnlyPane<>(site);
    }
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> onTimePane() {
      return new ExtractOnTimePane<>();
    }
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> finalPane() {
      return new ExtractFinalPane<>();
    }
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> nonLatePanes() {
      return new ExtractNonLatePanes<>();
    }
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> earlyPanes() {
      return new ExtractEarlyPanes<>();
    }
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> latePanes() {
      return new ExtractLatePanes<>();
    }
  
    static <T> SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> allPanes() {
      return new ExtractAllPanes<>();
    }
  
    private static class ExtractOnlyPane<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      private final PAssert.PAssertionSite site;
  
      private ExtractOnlyPane(PAssert.PAssertionSite site) {
        this.site = site;
      }
  
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          if (!value.getPaneInfo().isFirst() || !value.getPaneInfo().isLast()) {
            throw site.wrap(
                String.format(
                    "Expected elements to be produced by a trigger that fires at most once, but got "
                        + "a value %s in a pane that is %s.",
                    value,
                    value.getPaneInfo().isFirst()
                        ? "not the last paneInfo"
                        : "not the first paneInfo"));
          }
          outputs.add(value.getValue());
        }
        return outputs;
      }
    }
  
    private static class ExtractOnTimePane<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          if (value.getPaneInfo().getTiming().equals(Timing.ON_TIME)) {
            outputs.add(value.getValue());
          }
        }
        return outputs;
      }
    }
  
    private static class ExtractFinalPane<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          if (value.getPaneInfo().isLast()) {
            outputs.add(value.getValue());
          }
        }
        return outputs;
      }
    }
  
    private static class ExtractAllPanes<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          outputs.add(value.getValue());
        }
        return outputs;
      }
    }
  
    private static class ExtractNonLatePanes<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          if (value.getPaneInfo().getTiming() != PaneInfo.Timing.LATE) {
            outputs.add(value.getValue());
          }
        }
        return outputs;
      }
    }
  
    private static class ExtractEarlyPanes<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          if (value.getPaneInfo().getTiming() == PaneInfo.Timing.EARLY) {
            outputs.add(value.getValue());
          }
        }
        return outputs;
      }
    }
  
    private static class ExtractLatePanes<T>
        extends SimpleFunction<Iterable<ValueInSingleWindow<T>>, Iterable<T>> {
      @Override
      public Iterable<T> apply(Iterable<ValueInSingleWindow<T>> input) {
        List<T> outputs = new ArrayList<>();
        for (ValueInSingleWindow<T> value : input) {
          if (value.getPaneInfo().getTiming() == PaneInfo.Timing.LATE) {
            outputs.add(value.getValue());
          }
        }
        return outputs;
      }
    }
  }
  