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 static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Objects;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.IncompatibleWindowException;
  import org.apache.beam.sdk.transforms.windowing.NonMergingWindowFn;
  import org.apache.beam.sdk.transforms.windowing.WindowFn;
  import org.apache.beam.sdk.transforms.windowing.WindowMappingFn;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Supplier;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
  import org.joda.time.Duration;
  
  /**
   * A {@link WindowFn} that assigns all elements to a static collection of {@link BoundedWindow
   * BoundedWindows}. Side inputs windowed into static windows only support main input windows in the
   * provided collection of windows.
   */
  final class StaticWindows extends NonMergingWindowFn<Object, BoundedWindow> {
    private final Supplier<Collection<BoundedWindow>> windows;
    private final Coder<BoundedWindow> coder;
  
    private final boolean onlyExisting;
  
    private StaticWindows(
        Supplier<Collection<BoundedWindow>> windows,
        Coder<BoundedWindow> coder,
        boolean onlyExisting) {
      this.windows = windows;
      this.coder = coder;
      this.onlyExisting = onlyExisting;
    }
  
    public static <W extends BoundedWindow> StaticWindows of(Coder<W> coder, Iterable<W> windows) {
      checkArgument(!Iterables.isEmpty(windows), "Input windows to StaticWindows may not be empty");
      @SuppressWarnings("unchecked")
      StaticWindows windowFn =
          new StaticWindows(
              WindowSupplier.of((Coder<BoundedWindow>) coder, (Iterable<BoundedWindow>) windows),
              (Coder<BoundedWindow>) coder,
              false);
      return windowFn;
    }
  
    public static <W extends BoundedWindow> StaticWindows of(Coder<W> coder, W window) {
      return of(coder, Collections.singleton(window));
    }
  
    public StaticWindows intoOnlyExisting() {
      return new StaticWindows(windows, coder, true);
    }
  
    public Collection<BoundedWindow> getWindows() {
      return windows.get();
    }
  
    @Override
    public Collection<BoundedWindow> assignWindows(AssignContext c) throws Exception {
      if (onlyExisting) {
        checkArgument(
            windows.get().contains(c.window()),
            "Tried to assign windows to an element that is not already windowed into a provided "
                + "window when onlyExisting is set to true");
        return Collections.singleton(c.window());
      } else {
        return getWindows();
      }
    }
  
    @Override
    public boolean isCompatible(WindowFn<?, ?> other) {
      if (!(other instanceof StaticWindows)) {
        return false;
      }
      StaticWindows that = (StaticWindows) other;
      return Objects.equals(this.windows.get(), that.windows.get());
    }
  
    @Override
    public void verifyCompatibility(WindowFn<?, ?> other) throws IncompatibleWindowException {
      if (!this.isCompatible(other)) {
        throw new IncompatibleWindowException(
            other,
            String.format(
                "Only %s objects with the same window supplier are compatible.",
                StaticWindows.class.getSimpleName()));
      }
    }
  
    @Override
    public Coder<BoundedWindow> windowCoder() {
      return coder;
    }
  
    @Override
    public WindowMappingFn<BoundedWindow> getDefaultWindowMappingFn() {
      return new WindowMappingFn<BoundedWindow>(Duration.millis(Long.MAX_VALUE)) {
        @Override
        public BoundedWindow getSideInputWindow(BoundedWindow mainWindow) {
          checkArgument(
              windows.get().contains(mainWindow),
              "%s only supports side input windows for main input windows that it contains",
              StaticWindows.class.getSimpleName());
          return mainWindow;
        }
      };
    }
  
    @Override
    public boolean assignsToOneWindow() {
      return true;
    }
  }
  