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.oss.driver.internal.core.cql;
  
  import com.datastax.oss.driver.api.core.CqlSession;
  import com.datastax.oss.driver.api.core.cql.AsyncResultSet;
  import com.datastax.oss.driver.api.core.cql.ColumnDefinitions;
  import com.datastax.oss.driver.api.core.cql.ExecutionInfo;
  import com.datastax.oss.driver.api.core.cql.Row;
  import com.datastax.oss.driver.api.core.cql.Statement;
  import com.datastax.oss.driver.api.core.type.DataTypes;
  import com.datastax.oss.driver.internal.core.context.InternalDriverContext;
  import com.datastax.oss.driver.internal.core.util.CountingIterator;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.nio.ByteBuffer;
  import java.util.Collections;
  import java.util.List;
  import java.util.Queue;
  import java.util.concurrent.CompletionStage;
  import net.jcip.annotations.NotThreadSafe;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  @NotThreadSafe // wraps a mutable queue
  public class DefaultAsyncResultSet implements AsyncResultSet {
  
    private static final Logger LOG = LoggerFactory.getLogger(DefaultAsyncResultSet.class);
  
    private final ColumnDefinitions definitions;
    private final ExecutionInfo executionInfo;
    private final CqlSession session;
    private final CountingIterator<Row> iterator;
    private final Iterable<Row> currentPage;
  
    public DefaultAsyncResultSet(
        ColumnDefinitions definitions,
        ExecutionInfo executionInfo,
        Queue<List<ByteBuffer>> data,
        CqlSession session,
        InternalDriverContext context) {
      this.definitions = definitions;
      this.executionInfo = executionInfo;
      this.session = session;
      this.iterator =
          new CountingIterator<Row>(data.size()) {
            @Override
            protected Row computeNext() {
              List<ByteBuffer> rowData = data.poll();
              return (rowData == null) ? endOfData() : new DefaultRow(definitions, rowData, context);
            }
          };
      this.currentPage = () -> iterator;
    }
  
    @NonNull
    @Override
    public ColumnDefinitions getColumnDefinitions() {
      return definitions;
    }
  
    @NonNull
    @Override
    public ExecutionInfo getExecutionInfo() {
      return executionInfo;
    }
  
    @NonNull
    @Override
    public Iterable<Row> currentPage() {
      return currentPage;
    }
  
    @Override
    public int remaining() {
      return iterator.remaining();
    }
  
    @Override
    public boolean hasMorePages() {
      return executionInfo.getPagingState() != null;
    }
  
    @NonNull
    @Override
    public CompletionStage<AsyncResultSet> fetchNextPage() throws IllegalStateException {
      ByteBuffer nextState = executionInfo.getPagingState();
      if (nextState == null) {
        throw new IllegalStateException(
            "No next page. Use #hasMorePages before calling this method to avoid this error.");
      }
      Statement<?> statement = (Statement<?>) executionInfo.getRequest();
      LOG.trace("Fetching next page for {}", statement);
      Statement<?> nextStatement = statement.copy(nextState);
      return session.executeAsync(nextStatement);
    }
  
    @Override
    public boolean wasApplied() {
      if (!definitions.contains("[applied]")
          || !definitions.get("[applied]").getType().equals(DataTypes.BOOLEAN)) {
        return true;
      } else if (iterator.hasNext()) {
        // Note that [applied] has the same value for all rows, so as long as we have a row we don't
        // care which one it is.
        return iterator.peek().getBoolean("[applied]");
      } else {
        // If the server provided [applied], it means there was at least one row. So if we get here it
        // means the client consumed all the rows before, we can't handle that case because we have
        // nowhere left to read the boolean from.
        throw new IllegalStateException("This method must be called before consuming all the rows");
      }
    }
  
    static AsyncResultSet empty(final ExecutionInfo executionInfo) {
      return new AsyncResultSet() {
        @NonNull
        @Override
        public ColumnDefinitions getColumnDefinitions() {
          return EmptyColumnDefinitions.INSTANCE;
        }
  
        @NonNull
        @Override
        public ExecutionInfo getExecutionInfo() {
          return executionInfo;
        }
  
        @NonNull
        @Override
        public Iterable<Row> currentPage() {
          return Collections.emptyList();
        }
  
        @Override
        public int remaining() {
          return 0;
        }
  
        @Override
        public boolean hasMorePages() {
          return false;
        }
  
        @NonNull
        @Override
        public CompletionStage<AsyncResultSet> fetchNextPage() throws IllegalStateException {
          throw new IllegalStateException(
              "No next page. Use #hasMorePages before calling this method to avoid this error.");
        }
  
        @Override
        public boolean wasApplied() {
          return true;
        }
      };
    }
  }
  