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 com.datastax.dse.driver.internal.core.graph;
  
  import com.datastax.dse.driver.api.core.graph.AsyncGraphResultSet;
  import com.datastax.dse.driver.api.core.graph.GraphNode;
  import com.datastax.oss.driver.api.core.cql.ExecutionInfo;
  import com.datastax.oss.driver.internal.core.util.CountingIterator;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.util.Collections;
  import java.util.Queue;
  import java.util.concurrent.CompletionStage;
  import net.jcip.annotations.NotThreadSafe;
  
  @NotThreadSafe // wraps a mutable queue
  public class ContinuousAsyncGraphResultSet implements AsyncGraphResultSet {
  
    private final CountingIterator<GraphNode> iterator;
    private final int pageNumber;
    private final boolean hasMorePages;
    private final ExecutionInfo executionInfo;
    private final ContinuousGraphRequestHandler continuousGraphRequestHandler;
    private final Iterable<GraphNode> currentPage;
  
    public ContinuousAsyncGraphResultSet(
        ExecutionInfo executionInfo,
        Queue<GraphNode> data,
        int pageNumber,
        boolean hasMorePages,
        ContinuousGraphRequestHandler continuousGraphRequestHandler,
        GraphProtocol graphProtocol) {
  
      this.iterator = new GraphResultIterator(data, graphProtocol);
      this.pageNumber = pageNumber;
      this.hasMorePages = hasMorePages;
      this.executionInfo = executionInfo;
      this.continuousGraphRequestHandler = continuousGraphRequestHandler;
      this.currentPage = () -> iterator;
    }
  
    @NonNull
    @Override
    public ExecutionInfo getRequestExecutionInfo() {
      return executionInfo;
    }
  
    @NonNull
    @Override
    @Deprecated
    public com.datastax.dse.driver.api.core.graph.GraphExecutionInfo getExecutionInfo() {
      return GraphExecutionInfoConverter.convert(executionInfo);
    }
  
    @Override
    public int remaining() {
      return iterator.remaining();
    }
  
    @NonNull
    @Override
    public Iterable<GraphNode> currentPage() {
      return currentPage;
    }
  
    @Override
    public boolean hasMorePages() {
      return hasMorePages;
    }
  
    @NonNull
    @Override
    public CompletionStage<AsyncGraphResultSet> fetchNextPage() throws IllegalStateException {
      if (!hasMorePages()) {
        throw new IllegalStateException(
            "Can't call fetchNextPage() on the last page (use hasMorePages() to check)");
      }
      return continuousGraphRequestHandler.fetchNextPage();
    }
  
    @Override
    public void cancel() {
      continuousGraphRequestHandler.cancel();
    }
  
    /** Returns the current page's number. Pages are numbered starting from 1. */
    public int pageNumber() {
      return pageNumber;
    }
  
    static AsyncGraphResultSet empty(ExecutionInfo executionInfo) {
  
      return new AsyncGraphResultSet() {
  
        @NonNull
        @Override
        public ExecutionInfo getRequestExecutionInfo() {
          return executionInfo;
        }
  
        @NonNull
        @Override
        @Deprecated
        public com.datastax.dse.driver.api.core.graph.GraphExecutionInfo getExecutionInfo() {
          return GraphExecutionInfoConverter.convert(executionInfo);
        }
  
        @NonNull
        @Override
        public Iterable<GraphNode> currentPage() {
          return Collections.emptyList();
        }
  
        @Override
        public int remaining() {
          return 0;
        }
  
        @Override
        public boolean hasMorePages() {
          return false;
        }
  
        @NonNull
        @Override
        public CompletionStage<AsyncGraphResultSet> fetchNextPage() throws IllegalStateException {
          throw new IllegalStateException(
              "Can't call fetchNextPage() on the last page (use hasMorePages() to check)");
        }
  
        @Override
        public void cancel() {
          // noop
        }
      };
    }
  }
  