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.spark.connector.japi.rdd;
  
  import org.apache.spark.api.java.JavaPairRDD;
  import org.apache.spark.api.java.JavaRDD;
  import org.apache.spark.api.java.function.Function;
  import scala.collection.Seq;
  import scala.reflect.ClassTag;
  
  import com.datastax.spark.connector.ColumnRef;
  import com.datastax.spark.connector.cql.CassandraConnector;
  import com.datastax.spark.connector.japi.CassandraJavaUtil;
  import com.datastax.spark.connector.japi.SparkContextJavaFunctions;
  import com.datastax.spark.connector.japi.StreamingContextJavaFunctions;
  import com.datastax.spark.connector.rdd.CassandraRDD;
  import com.datastax.spark.connector.rdd.ReadConf;
  import com.datastax.spark.connector.util.JavaApiHelper;
  
  import static com.datastax.spark.connector.japi.CassandraJavaUtil.toSelectableColumnRefs;
  import static com.datastax.spark.connector.util.JavaApiHelper.getClassTag;
  import static com.datastax.spark.connector.util.JavaApiHelper.toScalaSeq;
  
  /**
   * A Java API wrapper over {@link CassandraRDD} to provide Spark Cassandra Connector functionality in
   * Java.
   * <p/>
   * The wrapper can be obtained by one of the methods of {@link SparkContextJavaFunctions} or {@link
   * StreamingContextJavaFunctions}.
   */
  @SuppressWarnings({"unchecked", "UnusedDeclaration"})
  public class CassandraJavaRDD<R> extends JavaRDD<R> {
  
      public CassandraJavaRDD(CassandraRDD<R> rdd, Class<R> clazz) {
          super(rdd, getClassTag(clazz));
      }
  
      public CassandraJavaRDD(CassandraRDD<R> rdd, ClassTag<R> classTag) {
          super(rdd, classTag);
      }
  
      @Override
      public CassandraRDD<R> rdd() {
          return (CassandraRDD<R>) super.rdd();
      }
  
      protected CassandraJavaRDD<R> wrap(CassandraRDD<R> newRDD) {
          return new CassandraJavaRDD<>(newRDD, classTag());
      }
  
      /**
       * Narrows down the selected set of columns.
       * <p/>
       * Use this for better performance, when you don't need all the columns in the result RDD. When
       * called multiple times, it selects the subset of the already selected columns, so after a column
       * was removed by the previous {@code select} call, it is not possible to add it back.
       */
      public CassandraJavaRDD<R> select(String... columnNames) {
          Seq<ColumnRef> columnRefs = toScalaSeq(toSelectableColumnRefs(columnNames));
          CassandraRDD<R> newRDD = rdd().select(columnRefs.toSeq());
          return wrap(newRDD);
      }
  
      /**
       * Narrows down the selected set of columns.
       * <p/>
       * Use this for better performance, when you don't need all the columns in the result RDD. When
       * called multiple times, it selects the subset of the already selected columns, so after a column
       * was removed by the previous {@code select} call, it is not possible to add it back.</p>
       */
      public CassandraJavaRDD<R> select(ColumnRef... columns) {
          Seq<ColumnRef> columnRefs = JavaApiHelper.toScalaSeq(columns);
          CassandraRDD<R> newRDD = rdd().select(columnRefs.toSeq());
          return wrap(newRDD);
      }
  
      /**
       * Adds a CQL {@code WHERE} predicate(s) to the query.
       * <p/>
       * Useful for leveraging secondary indexes in Cassandra. Implicitly adds an {@code ALLOW FILTERING}
       * clause to the {@code WHERE} clause, however beware that some predicates might be rejected by
       * Cassandra, particularly in cases when they filter on an unindexed, non-clustering column.</p>
       */
      public CassandraJavaRDD<R> where(String cqlWhereClause, Object... args) {
          CassandraRDD<R> newRDD = rdd().where(cqlWhereClause, toScalaSeq(args));
          return wrap(newRDD);
      }
  
      /**
       * Forces the rows within a selected Cassandra partition to be returned in ascending order (if
       * possible).
       */
      public CassandraJavaRDD<R> withAscOrder() {
          CassandraRDD<R> newRDD = rdd().withAscOrder();
          return wrap(newRDD);
      }
  
      /**
       * Forces the rows within a selected Cassandra partition to be returned in descending order (if
       * possible).
       */
      public CassandraJavaRDD<R> withDescOrder() {
          CassandraRDD<R> newRDD = rdd().withDescOrder();
          return wrap(newRDD);
      }
  
      /**
       * Returns the columns to be selected from the table.
       */
      @SuppressWarnings("RedundantCast")
      public ColumnRef[] selectedColumnRefs() {
          ClassTag<ColumnRef> classTag = getClassTag(ColumnRef.class);
          return (ColumnRef[]) rdd().selectedColumnRefs().toArray(classTag);
      }
  
      /**
       * Returns the names of columns to be selected from the table.
       */
      @SuppressWarnings("RedundantCast")
      public String[] selectedColumnNames() {
          ClassTag<String> classTag = getClassTag(String.class);
          return (String[]) rdd().selectedColumnNames().toArray(classTag);
      }
  
      /**
       * Returns a copy of this RDD with connector changed to the specified one.
       */
      public CassandraJavaRDD<R> withConnector(CassandraConnector connector) {
          CassandraRDD<R> newRDD = rdd().withConnector(connector);
          return wrap(newRDD);
      }
  
      /**
       * Returns a copy of this RDD with read configuration changed to the specified one.
       */
      public CassandraJavaRDD<R> withReadConf(ReadConf config) {
          CassandraRDD<R> newRDD = rdd().withReadConf(config);
          return wrap(newRDD);
      }
  
      /**
       * Adds the limit clause to CQL select statement. The limit will be applied for each created Spark
       * partition. In other words, unless the data are fetched from a single Cassandra partition the
       * number of results is unpredictable.
       * <p/>
       * The main purpose of passing limit clause is to fetch top n rows from a single Cassandra partition
       * when the table is designed so that it uses clustering keys and a partition key predicate is passed
       * to the where clause.
       */
      public CassandraJavaRDD<R> limit(Long rowsNumber) {
          CassandraRDD<R> newRDD = rdd().limit(rowsNumber);
          return wrap(newRDD);
      }
  
      /**
       * Adds the PER PARTITION LIMIT clause to CQL select statement. The limit will be applied for each
       * Cassandra Partition
       */
      public CassandraJavaRDD<R> perPartitionLimit(Long rowsNumber) {
          CassandraRDD<R> newRDD = rdd().perPartitionLimit(rowsNumber);
          return wrap(newRDD);
      }
  
      /**
       * Applies a function to each item, and groups consecutive items having the same value together.
       * Contrary to `groupBy`, items from the same group must be already next to each other in the
       * original collection. Works locally on each partition, so items from different partitions will
       * never be placed in the same group.
       */
      public <K> JavaPairRDD<K, Iterable<R>> spanBy(Function<R, K> f, ClassTag<K> keyClassTag) {
          return CassandraJavaUtil.javaFunctions(rdd()).spanBy(f, keyClassTag);
      }
  
      /**
       * @see {@link #spanBy(Function, ClassTag)}
       */
      public <K> JavaPairRDD<K, Iterable<R>> spanBy(Function<R, K> f, Class<K> keyClass) {
          return CassandraJavaUtil.javaFunctions(rdd()).spanBy(f, getClassTag(keyClass));
      }
  
      /**
       * Produces the empty CassandraRDD which has the same signature and properties, but it does not
       * perform any validation and it does not even try to return any rows.
       */
      public CassandraJavaRDD<R> toEmptyCassandraRDD() {
          CassandraRDD<R> newRDD = rdd().toEmptyCassandraRDD();
          return wrap(newRDD);
      }
  
      /**
       * Counts the number of items in this RDD by selecting count(*) on Cassandra table.
       */
      public long cassandraCount() {
          return rdd().cassandraCount();
      }
  }
  