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.calcite.adapter.splunk;
  
  import org.apache.calcite.adapter.enumerable.EnumerableConvention;
  import org.apache.calcite.adapter.enumerable.EnumerableRel;
  import org.apache.calcite.adapter.enumerable.EnumerableRelImplementor;
  import org.apache.calcite.adapter.enumerable.PhysType;
  import org.apache.calcite.adapter.enumerable.PhysTypeImpl;
  import org.apache.calcite.config.CalciteSystemProperty;
  import org.apache.calcite.linq4j.tree.BlockBuilder;
  import org.apache.calcite.linq4j.tree.Expression;
  import org.apache.calcite.linq4j.tree.Expressions;
  import org.apache.calcite.linq4j.tree.Types;
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelOptPlanner;
  import org.apache.calcite.plan.RelOptTable;
  import org.apache.calcite.rel.RelWriter;
  import org.apache.calcite.rel.core.TableScan;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.runtime.Hook;
  import org.apache.calcite.util.Util;
  
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableMap;
  
  import java.lang.reflect.Method;
  import java.util.AbstractList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Map;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Relational expression representing a scan of Splunk.
   *
   * <p>Splunk does not have tables, but it's easiest to imagine that a Splunk
   * instance is one large table. This "table" does not have a fixed set of
   * columns (Splunk calls them "fields") but each query specifies the fields that
   * it wants. It also specifies a search expression, and optionally earliest and
   * latest dates.
   */
  public class SplunkTableScan
      extends TableScan
      implements EnumerableRel {
    final SplunkTable splunkTable;
    final String search;
    final String earliest;
    final String latest;
    final List<String> fieldList;
  
    protected SplunkTableScan(
        RelOptCluster cluster,
        RelOptTable table,
        SplunkTable splunkTable,
        String search,
        String earliest,
        String latest,
        List<String> fieldList) {
      super(
          cluster,
          cluster.traitSetOf(EnumerableConvention.INSTANCE),
          ImmutableList.of(),
          table);
      this.splunkTable = requireNonNull(splunkTable, "splunkTable");
      this.search = requireNonNull(search, "search");
      this.earliest = earliest;
      this.latest = latest;
      this.fieldList = fieldList;
    }
  
    @Override public RelWriter explainTerms(RelWriter pw) {
      return super.explainTerms(pw)
          .item("table", table.getQualifiedName())
          .item("earliest", earliest)
          .item("latest", latest)
          .item("fieldList", fieldList);
    }
  
    @Override public void register(RelOptPlanner planner) {
      planner.addRule(SplunkPushDownRule.FILTER);
      planner.addRule(SplunkPushDownRule.FILTER_ON_PROJECT);
      planner.addRule(SplunkPushDownRule.PROJECT);
      planner.addRule(SplunkPushDownRule.PROJECT_ON_FILTER);
    }
  
    @Override public RelDataType deriveRowType() {
      final RelDataTypeFactory.Builder builder =
          getCluster().getTypeFactory().builder();
      for (String field : fieldList) {
        // REVIEW: is case-sensitive match what we want here?
        builder.add(table.getRowType().getField(field, true, false));
      }
      return builder.build();
    }
  
    private static final Method METHOD =
        Types.lookupMethod(
            SplunkTable.SplunkTableQueryable.class,
            "createQuery",
            String.class,
            String.class,
            String.class,
            List.class);
  
    @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
      Map map = ImmutableMap.builder()
          .put("search", search)
          .put("earliest", Util.first(earliest, ""))
          .put("latest", Util.first(latest, ""))
          .put("fieldList", fieldList)
          .build();
      if (CalciteSystemProperty.DEBUG.value()) {
        System.out.println("Splunk: " + map);
      }
      Hook.QUERY_PLAN.run(map);
  
      final PhysType physType =
          PhysTypeImpl.of(
              implementor.getTypeFactory(),
              getRowType(),
              pref.preferCustom());
      final BlockBuilder builder = new BlockBuilder();
      return implementor.result(
          physType,
          builder.append(
              Expressions.call(
                  table.getExpression(SplunkTable.SplunkTableQueryable.class),
                  METHOD,
                  Expressions.constant(search),
                  Expressions.constant(earliest),
                  Expressions.constant(latest),
                  fieldList == null
                      ? Expressions.constant(null)
                      : constantStringList(fieldList))).toBlock());
    }
  
    private static Expression constantStringList(final List<String> strings) {
      return Expressions.call(
          Arrays.class,
          "asList",
          Expressions.newArrayInit(
              Object.class,
              new AbstractList<Expression>() {
                @Override public Expression get(int index) {
                  return Expressions.constant(strings.get(index));
                }
  
                @Override public int size() {
                  return strings.size();
                }
              }));
    }
  }
  