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.transforms.windowing;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument;
  
  import java.util.Arrays;
  import java.util.List;
  import org.apache.beam.sdk.transforms.windowing.Trigger.OnceTrigger;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Joiner;
  import org.joda.time.Instant;
  
  /**
   * A composite {@link Trigger} that fires once after at least one of its sub-triggers have fired.
   */
  public class AfterFirst extends OnceTrigger {
  
    AfterFirst(List<Trigger> subTriggers) {
      super(subTriggers);
      checkArgument(subTriggers.size() > 1);
    }
  
    /** Returns an {@code AfterFirst} {@code Trigger} with the given subtriggers. */
    public static AfterFirst of(OnceTrigger... triggers) {
      return new AfterFirst(Arrays.asList(triggers));
    }
  
    /** Returns an {@code AfterFirst} {@code Trigger} with the given subtriggers. */
    public static AfterFirst of(List<Trigger> triggers) {
      return new AfterFirst(triggers);
    }
  
    @Override
    public Instant getWatermarkThatGuaranteesFiring(BoundedWindow window) {
      // This trigger will fire after the earliest of its sub-triggers.
      Instant deadline = BoundedWindow.TIMESTAMP_MAX_VALUE;
      for (Trigger subTrigger : subTriggers) {
        Instant subDeadline = subTrigger.getWatermarkThatGuaranteesFiring(window);
        if (deadline.isAfter(subDeadline)) {
          deadline = subDeadline;
        }
      }
      return deadline;
    }
  
    @Override
    protected OnceTrigger getContinuationTrigger(List<Trigger> continuationTriggers) {
      return new AfterFirst(continuationTriggers);
    }
  
    @Override
    public String toString() {
      StringBuilder builder = new StringBuilder("AfterFirst.of(");
      Joiner.on(", ").appendTo(builder, subTriggers);
      builder.append(")");
  
      return builder.toString();
    }
  }
  