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.extensions.sql.impl;
  
  import com.google.auto.value.AutoValue;
  import java.util.Arrays;
  import java.util.Collection;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.extensions.sql.impl.utils.TVFStreamingUtils;
  import org.apache.beam.sdk.transforms.windowing.IntervalWindow;
  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.sdk.values.Row;
  import org.joda.time.Duration;
  
  /**
   * TVFSlidingWindowFn assigns window based on input row's "window_start" and "window_end"
   * timestamps.
   */
  @AutoValue
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public abstract class TVFSlidingWindowFn extends NonMergingWindowFn<Object, IntervalWindow> {
    /** Size of the generated windows. */
    public abstract Duration getSize();
  
    /** Amount of time between generated windows. */
    public abstract Duration getPeriod();
  
    public static TVFSlidingWindowFn of(Duration size, Duration period) {
      return new AutoValue_TVFSlidingWindowFn(size, period);
    }
  
    @Override
    public Collection<IntervalWindow> assignWindows(AssignContext c) throws Exception {
      Row curRow = (Row) c.element();
      // In sliding window as TVF syntax, each row contains's its window's start and end as metadata,
      // thus we can assign a window directly based on window's start and end metadata.
      return Arrays.asList(
          new IntervalWindow(
              curRow.getDateTime(TVFStreamingUtils.WINDOW_START).toInstant(),
              curRow.getDateTime(TVFStreamingUtils.WINDOW_END).toInstant()));
    }
  
    @Override
    public boolean isCompatible(WindowFn<?, ?> other) {
      return equals(other);
    }
  
    @Override
    public Coder<IntervalWindow> windowCoder() {
      return IntervalWindow.getCoder();
    }
  
    @Override
    public WindowMappingFn<IntervalWindow> getDefaultWindowMappingFn() {
      throw new UnsupportedOperationException(
          "TVFSlidingWindow does not support side input windows.");
    }
  }
  