/*
 * 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.phoenix.execute;

import java.sql.SQLException;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.phoenix.cache.ServerCacheClient.ServerCache;
import org.apache.phoenix.compile.ExplainPlanAttributes.ExplainPlanAttributesBuilder;
import org.apache.phoenix.compile.GroupByCompiler.GroupBy;
import org.apache.phoenix.compile.OrderByCompiler.OrderBy;
import org.apache.phoenix.compile.RowProjector;
import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.execute.visitor.QueryPlanVisitor;
import org.apache.phoenix.hbase.index.util.ImmutableBytesPtr;
import org.apache.phoenix.iterate.ParallelIteratorFactory;
import org.apache.phoenix.iterate.ParallelScanGrouper;
import org.apache.phoenix.iterate.ResultIterator;
import org.apache.phoenix.iterate.SequenceResultIterator;
import org.apache.phoenix.optimize.Cost;
import org.apache.phoenix.parse.FilterableStatement;
import org.apache.phoenix.query.KeyRange;
import org.apache.phoenix.schema.TableRef;
import org.apache.phoenix.schema.tuple.SingleKeyValueTuple;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.util.SQLCloseables;

public class LiteralResultIterationPlan extends BaseQueryPlan {
  protected final Iterable<Tuple> tuples;

  public LiteralResultIterationPlan(StatementContext context, FilterableStatement statement,
    TableRef tableRef, RowProjector projection, Integer limit, Integer offset, OrderBy orderBy,
    ParallelIteratorFactory parallelIteratorFactory) throws SQLException {
    this(Collections.<Tuple> singletonList(new SingleKeyValueTuple(KeyValue.LOWESTKEY)), context,
      statement, tableRef, projection, limit, offset, orderBy, parallelIteratorFactory);
  }

  public LiteralResultIterationPlan(Iterable<Tuple> tuples, StatementContext context,
    FilterableStatement statement, TableRef tableRef, RowProjector projection, Integer limit,
    Integer offset, OrderBy orderBy, ParallelIteratorFactory parallelIteratorFactory)
    throws SQLException {
    super(context, statement, tableRef, projection, context.getBindManager().getParameterMetaData(),
      limit, offset, orderBy, GroupBy.EMPTY_GROUP_BY, parallelIteratorFactory, null);
    this.tuples = tuples;
  }

  @Override
  public Cost getCost() {
    return Cost.ZERO;
  }

  @Override
  public List<KeyRange> getSplits() {
    return Collections.emptyList();
  }

  @Override
  public List<List<Scan>> getScans() {
    return Collections.emptyList();
  }

  @Override
  public boolean useRoundRobinIterator() throws SQLException {
    return false;
  }

  @Override
  public <T> T accept(QueryPlanVisitor<T> visitor) {
    return visitor.visit(this);
  }

  @Override
  protected ResultIterator newIterator(ParallelScanGrouper scanGrouper, Scan scan,
    final Map<ImmutableBytesPtr, ServerCache> caches) throws SQLException {
    ResultIterator scanner = new ResultIterator() {
      private final Iterator<Tuple> tupleIterator = tuples.iterator();
      private boolean closed = false;
      private int count = 0;
      private int offsetCount = 0;

      @Override
      public void close() throws SQLException {
        SQLCloseables.closeAll(caches.values());
        caches.clear();
        this.closed = true;
      }

      @Override
      public Tuple next() throws SQLException {
        while (
          !this.closed && (offset != null && offsetCount < offset) && tupleIterator.hasNext()
        ) {
          offsetCount++;
          tupleIterator.next();
        }
        if (!this.closed && (limit == null || count++ < limit) && tupleIterator.hasNext()) {
          return tupleIterator.next();
        }
        return null;
      }

      @Override
      public void explain(List<String> planSteps) {
      }

      @Override
      public void explain(List<String> planSteps,
        ExplainPlanAttributesBuilder explainPlanAttributesBuilder) {
      }

    };

    if (context.getSequenceManager().getSequenceCount() > 0) {
      scanner = new SequenceResultIterator(scanner, context.getSequenceManager());
    }

    return scanner;
  }

  @Override
  public Long getEstimatedRowsToScan() {
    return 0l;
  }

  @Override
  public Long getEstimatedBytesToScan() {
    return 0l;
  }

  @Override
  public Long getEstimateInfoTimestamp() throws SQLException {
    return 0l;
  }

  @Override
  public List<OrderBy> getOutputOrderBys() {
    return Collections.<OrderBy> emptyList();
  }
}
