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.kafka.streams.kstream.internals.graph;
  
  import org.apache.kafka.streams.errors.TopologyException;
  
  public final class GraphGraceSearchUtil {
      private GraphGraceSearchUtil() {}
  
      public static long findAndVerifyWindowGrace(final GraphNode graphNode) {
          return findAndVerifyWindowGrace(graphNode, "");
      }
  
      @SuppressWarnings("rawtypes")
      private static long findAndVerifyWindowGrace(final GraphNode graphNode, final String chain) {
          // error base case: we traversed off the end of the graph without finding a window definition
          if (graphNode == null) {
              throw new TopologyException(
                  "Window close time is only defined for windowed computations. Got [" + chain + "]."
              );
          }
          // base case: return if this node defines a grace period.
          if (graphNode instanceof GracePeriodGraphNode) {
              return ((GracePeriodGraphNode) graphNode).gracePeriod();
          }
  
          final String newChain = chain.equals("") ? graphNode.nodeName() : graphNode.nodeName() + "->" + chain;
  
          if (graphNode.parentNodes().isEmpty()) {
              // error base case: we traversed to the end of the graph without finding a window definition
              throw new TopologyException(
                  "Window close time is only defined for windowed computations. Got [" + newChain + "]."
              );
          }
  
          // recursive case: all parents must define a grace period, and we use the max of our parents' graces.
          long inheritedGrace = -1;
          for (final GraphNode parentNode : graphNode.parentNodes()) {
              final long parentGrace = findAndVerifyWindowGrace(parentNode, newChain);
              inheritedGrace = Math.max(inheritedGrace, parentGrace);
          }
  
          if (inheritedGrace == -1) {
              throw new IllegalStateException(); // shouldn't happen, and it's not a legal grace period
          }
  
          return inheritedGrace;
      }
  
  }
  