/*
 * 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.tools;

import org.apache.calcite.adapter.enumerable.EnumerableRules;
import org.apache.calcite.config.CalciteConnectionConfig;
import org.apache.calcite.interpreter.NoneToBindableConverterRule;
import org.apache.calcite.plan.RelOptCostImpl;
import org.apache.calcite.plan.RelOptLattice;
import org.apache.calcite.plan.RelOptMaterialization;
import org.apache.calcite.plan.RelOptPlanner;
import org.apache.calcite.plan.RelOptRule;
import org.apache.calcite.plan.RelOptUtil;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.plan.hep.HepMatchOrder;
import org.apache.calcite.plan.hep.HepPlanner;
import org.apache.calcite.plan.hep.HepProgram;
import org.apache.calcite.plan.hep.HepProgramBuilder;
import org.apache.calcite.prepare.CalcitePrepareImpl;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.Calc;
import org.apache.calcite.rel.core.RelFactories;
import org.apache.calcite.rel.metadata.ChainedRelMetadataProvider;
import org.apache.calcite.rel.metadata.DefaultRelMetadataProvider;
import org.apache.calcite.rel.metadata.RelMetadataProvider;
import org.apache.calcite.rel.rules.AggregateExpandDistinctAggregatesRule;
import org.apache.calcite.rel.rules.AggregateReduceFunctionsRule;
import org.apache.calcite.rel.rules.AggregateStarTableRule;
import org.apache.calcite.rel.rules.CalcMergeRule;
import org.apache.calcite.rel.rules.FilterAggregateTransposeRule;
import org.apache.calcite.rel.rules.FilterCalcMergeRule;
import org.apache.calcite.rel.rules.FilterJoinRule;
import org.apache.calcite.rel.rules.FilterProjectTransposeRule;
import org.apache.calcite.rel.rules.FilterTableScanRule;
import org.apache.calcite.rel.rules.FilterToCalcRule;
import org.apache.calcite.rel.rules.JoinAssociateRule;
import org.apache.calcite.rel.rules.JoinCommuteRule;
import org.apache.calcite.rel.rules.JoinPushThroughJoinRule;
import org.apache.calcite.rel.rules.JoinToMultiJoinRule;
import org.apache.calcite.rel.rules.LoptOptimizeJoinRule;
import org.apache.calcite.rel.rules.MultiJoinOptimizeBushyRule;
import org.apache.calcite.rel.rules.ProjectCalcMergeRule;
import org.apache.calcite.rel.rules.ProjectMergeRule;
import org.apache.calcite.rel.rules.ProjectToCalcRule;
import org.apache.calcite.rel.rules.SemiJoinRule;
import org.apache.calcite.rel.rules.SortProjectTransposeRule;
import org.apache.calcite.rel.rules.SubQueryRemoveRule;
import org.apache.calcite.rel.rules.TableScanRule;
import org.apache.calcite.sql2rel.RelDecorrelator;
import org.apache.calcite.sql2rel.RelFieldTrimmer;
import org.apache.calcite.sql2rel.SqlToRelConverter;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;

import java.util.Arrays;
import java.util.List;

/**
 * Utilities for creating {@link Program}s.
 */
public class Programs {
  private static final Function<RuleSet, Program> RULE_SET_TO_PROGRAM =
      new Function<RuleSet, Program>() {
        public Program apply(RuleSet ruleSet) {
          return of(ruleSet);
        }
      };

  public static final ImmutableList<RelOptRule> CALC_RULES =
      ImmutableList.of(
          NoneToBindableConverterRule.INSTANCE,
          EnumerableRules.ENUMERABLE_CALC_RULE,
          EnumerableRules.ENUMERABLE_FILTER_TO_CALC_RULE,
          EnumerableRules.ENUMERABLE_PROJECT_TO_CALC_RULE,
          CalcMergeRule.INSTANCE,
          FilterCalcMergeRule.INSTANCE,
          ProjectCalcMergeRule.INSTANCE,
          FilterToCalcRule.INSTANCE,
          ProjectToCalcRule.INSTANCE,
          CalcMergeRule.INSTANCE,

          // REVIEW jvs 9-Apr-2006: Do we still need these two?  Doesn't the
          // combination of CalcMergeRule, FilterToCalcRule, and
          // ProjectToCalcRule have the same effect?
          FilterCalcMergeRule.INSTANCE,
          ProjectCalcMergeRule.INSTANCE);

  /** Program that converts filters and projects to {@link Calc}s. */
  public static final Program CALC_PROGRAM =
      calc(DefaultRelMetadataProvider.INSTANCE);

  /** Program that expands sub-queries. */
  public static final Program SUB_QUERY_PROGRAM =
      subQuery(DefaultRelMetadataProvider.INSTANCE);

  public static final ImmutableSet<RelOptRule> RULE_SET =
      ImmutableSet.of(
          EnumerableRules.ENUMERABLE_JOIN_RULE,
          EnumerableRules.ENUMERABLE_MERGE_JOIN_RULE,
          EnumerableRules.ENUMERABLE_SEMI_JOIN_RULE,
          EnumerableRules.ENUMERABLE_CORRELATE_RULE,
          EnumerableRules.ENUMERABLE_PROJECT_RULE,
          EnumerableRules.ENUMERABLE_FILTER_RULE,
          EnumerableRules.ENUMERABLE_AGGREGATE_RULE,
          EnumerableRules.ENUMERABLE_SORT_RULE,
          EnumerableRules.ENUMERABLE_LIMIT_RULE,
          EnumerableRules.ENUMERABLE_UNION_RULE,
          EnumerableRules.ENUMERABLE_INTERSECT_RULE,
          EnumerableRules.ENUMERABLE_MINUS_RULE,
          EnumerableRules.ENUMERABLE_TABLE_MODIFICATION_RULE,
          EnumerableRules.ENUMERABLE_VALUES_RULE,
          EnumerableRules.ENUMERABLE_WINDOW_RULE,
          SemiJoinRule.PROJECT,
          SemiJoinRule.JOIN,
          TableScanRule.INSTANCE,
          CalcitePrepareImpl.COMMUTE
              ? JoinAssociateRule.INSTANCE
              : ProjectMergeRule.INSTANCE,
          AggregateStarTableRule.INSTANCE,
          AggregateStarTableRule.INSTANCE2,
          FilterTableScanRule.INSTANCE,
          FilterProjectTransposeRule.INSTANCE,
          FilterJoinRule.FILTER_ON_JOIN,
          AggregateExpandDistinctAggregatesRule.INSTANCE,
          AggregateReduceFunctionsRule.INSTANCE,
          FilterAggregateTransposeRule.INSTANCE,
          JoinCommuteRule.INSTANCE,
          JoinPushThroughJoinRule.RIGHT,
          JoinPushThroughJoinRule.LEFT,
          SortProjectTransposeRule.INSTANCE);

  // private constructor for utility class
  private Programs() {}

  /** Creates a program that executes a rule set. */
  public static Program of(RuleSet ruleSet) {
    return new RuleSetProgram(ruleSet);
  }

  /** Creates a list of programs based on an array of rule sets. */
  public static List<Program> listOf(RuleSet... ruleSets) {
    return Lists.transform(Arrays.asList(ruleSets), RULE_SET_TO_PROGRAM);
  }

  /** Creates a list of programs based on a list of rule sets. */
  public static List<Program> listOf(List<RuleSet> ruleSets) {
    return Lists.transform(ruleSets, RULE_SET_TO_PROGRAM);
  }

  /** Creates a program from a list of rules. */
  public static Program ofRules(RelOptRule... rules) {
    return of(RuleSets.ofList(rules));
  }

  /** Creates a program from a list of rules. */
  public static Program ofRules(Iterable<? extends RelOptRule> rules) {
    return of(RuleSets.ofList(rules));
  }

  /** Creates a program that executes a sequence of programs. */
  public static Program sequence(Program... programs) {
    return new SequenceProgram(ImmutableList.copyOf(programs));
  }

  /** Creates a program that executes a list of rules in a HEP planner. */
  public static Program hep(Iterable<? extends RelOptRule> rules,
      boolean noDag, RelMetadataProvider metadataProvider) {
    final HepProgramBuilder builder = HepProgram.builder();
    for (RelOptRule rule : rules) {
      builder.addRuleInstance(rule);
    }
    return of(builder.build(), noDag, metadataProvider);
  }

  /** Creates a program that executes a {@link HepProgram}. */
  public static Program of(final HepProgram hepProgram, final boolean noDag,
      final RelMetadataProvider metadataProvider) {
    return new Program() {
      public RelNode run(RelOptPlanner planner, RelNode rel,
          RelTraitSet requiredOutputTraits,
          List<RelOptMaterialization> materializations,
          List<RelOptLattice> lattices) {
        final HepPlanner hepPlanner = new HepPlanner(hepProgram,
            null, noDag, null, RelOptCostImpl.FACTORY);

        List<RelMetadataProvider> list = Lists.newArrayList();
        if (metadataProvider != null) {
          list.add(metadataProvider);
        }
        hepPlanner.registerMetadataProviders(list);
        RelMetadataProvider plannerChain =
            ChainedRelMetadataProvider.of(list);
        rel.getCluster().setMetadataProvider(plannerChain);

        hepPlanner.setRoot(rel);
        return hepPlanner.findBestExp();
      }
    };
  }

  /** Creates a program that invokes heuristic join-order optimization
   * (via {@link org.apache.calcite.rel.rules.JoinToMultiJoinRule},
   * {@link org.apache.calcite.rel.rules.MultiJoin} and
   * {@link org.apache.calcite.rel.rules.LoptOptimizeJoinRule})
   * if there are 6 or more joins (7 or more relations). */
  public static Program heuristicJoinOrder(
      final Iterable<? extends RelOptRule> rules,
      final boolean bushy, final int minJoinCount) {
    return new Program() {
      public RelNode run(RelOptPlanner planner, RelNode rel,
          RelTraitSet requiredOutputTraits,
          List<RelOptMaterialization> materializations,
          List<RelOptLattice> lattices) {
        final int joinCount = RelOptUtil.countJoins(rel);
        final Program program;
        if (joinCount < minJoinCount) {
          program = ofRules(rules);
        } else {
          // Create a program that gathers together joins as a MultiJoin.
          final HepProgram hep = new HepProgramBuilder()
              .addRuleInstance(FilterJoinRule.FILTER_ON_JOIN)
              .addMatchOrder(HepMatchOrder.BOTTOM_UP)
              .addRuleInstance(JoinToMultiJoinRule.INSTANCE)
              .build();
          final Program program1 =
              of(hep, false, DefaultRelMetadataProvider.INSTANCE);

          // Create a program that contains a rule to expand a MultiJoin
          // into heuristically ordered joins.
          // We use the rule set passed in, but remove JoinCommuteRule and
          // JoinPushThroughJoinRule, because they cause exhaustive search.
          final List<RelOptRule> list = Lists.newArrayList(rules);
          list.removeAll(
              ImmutableList.of(JoinCommuteRule.INSTANCE,
                  JoinAssociateRule.INSTANCE,
                  JoinPushThroughJoinRule.LEFT,
                  JoinPushThroughJoinRule.RIGHT));
          list.add(bushy
              ? MultiJoinOptimizeBushyRule.INSTANCE
              : LoptOptimizeJoinRule.INSTANCE);
          final Program program2 = ofRules(list);

          program = sequence(program1, program2);
        }
        return program.run(
            planner, rel, requiredOutputTraits, materializations, lattices);
      }
    };
  }

  public static Program calc(RelMetadataProvider metadataProvider) {
    return hep(CALC_RULES, true, metadataProvider);
  }

  @Deprecated // to be removed before 2.0
  public static Program subquery(RelMetadataProvider metadataProvider) {
    return subQuery(metadataProvider);
  }

  public static Program subQuery(RelMetadataProvider metadataProvider) {
    return hep(
        ImmutableList.of((RelOptRule) SubQueryRemoveRule.FILTER,
            SubQueryRemoveRule.PROJECT,
            SubQueryRemoveRule.JOIN), true, metadataProvider);
  }

  public static Program getProgram() {
    return new Program() {
      public RelNode run(RelOptPlanner planner, RelNode rel,
          RelTraitSet requiredOutputTraits,
          List<RelOptMaterialization> materializations,
          List<RelOptLattice> lattices) {
        return null;
      }
    };
  }

  /** Returns the standard program used by Prepare. */
  public static Program standard() {
    return standard(DefaultRelMetadataProvider.INSTANCE);
  }

  /** Returns the standard program with user metadata provider. */
  public static Program standard(RelMetadataProvider metadataProvider) {

    final Program program1 =
        new Program() {
          public RelNode run(RelOptPlanner planner, RelNode rel,
              RelTraitSet requiredOutputTraits,
              List<RelOptMaterialization> materializations,
              List<RelOptLattice> lattices) {
            planner.setRoot(rel);

            for (RelOptMaterialization materialization : materializations) {
              planner.addMaterialization(materialization);
            }
            for (RelOptLattice lattice : lattices) {
              planner.addLattice(lattice);
            }

            final RelNode rootRel2 =
                rel.getTraitSet().equals(requiredOutputTraits)
                ? rel
                : planner.changeTraits(rel, requiredOutputTraits);
            assert rootRel2 != null;

            planner.setRoot(rootRel2);
            final RelOptPlanner planner2 = planner.chooseDelegate();
            final RelNode rootRel3 = planner2.findBestExp();
            assert rootRel3 != null : "could not implement exp";
            return rootRel3;
          }
        };

    return sequence(subQuery(metadataProvider),
        new DecorrelateProgram(),
        new TrimFieldsProgram(),
        program1,

        // Second planner pass to do physical "tweaks". This the first time that
        // EnumerableCalcRel is introduced.
        calc(metadataProvider));
  }

  /** Program backed by a {@link RuleSet}. */
  static class RuleSetProgram implements Program {
    final RuleSet ruleSet;

    private RuleSetProgram(RuleSet ruleSet) {
      this.ruleSet = ruleSet;
    }

    public RelNode run(RelOptPlanner planner, RelNode rel,
        RelTraitSet requiredOutputTraits,
        List<RelOptMaterialization> materializations,
        List<RelOptLattice> lattices) {
      planner.clear();
      for (RelOptRule rule : ruleSet) {
        planner.addRule(rule);
      }
      for (RelOptMaterialization materialization : materializations) {
        planner.addMaterialization(materialization);
      }
      for (RelOptLattice lattice : lattices) {
        planner.addLattice(lattice);
      }
      if (!rel.getTraitSet().equals(requiredOutputTraits)) {
        rel = planner.changeTraits(rel, requiredOutputTraits);
      }
      planner.setRoot(rel);
      return planner.findBestExp();

    }
  }

  /** Program that runs sub-programs, sending the output of the previous as
   * input to the next. */
  private static class SequenceProgram implements Program {
    private final ImmutableList<Program> programs;

    SequenceProgram(ImmutableList<Program> programs) {
      this.programs = programs;
    }

    public RelNode run(RelOptPlanner planner, RelNode rel,
        RelTraitSet requiredOutputTraits,
        List<RelOptMaterialization> materializations,
        List<RelOptLattice> lattices) {
      for (Program program : programs) {
        rel = program.run(
            planner, rel, requiredOutputTraits, materializations, lattices);
      }
      return rel;
    }
  }

  /** Program that de-correlates a query.
   *
   * <p>To work around
   * <a href="https://issues.apache.org/jira/browse/CALCITE-842">[CALCITE-842]
   * Decorrelator gets field offsets confused if fields have been trimmed</a>,
   * disable field-trimming in {@link SqlToRelConverter}, and run
   * {@link TrimFieldsProgram} after this program. */
  private static class DecorrelateProgram implements Program {
    public RelNode run(RelOptPlanner planner, RelNode rel,
        RelTraitSet requiredOutputTraits,
        List<RelOptMaterialization> materializations,
        List<RelOptLattice> lattices) {
      final CalciteConnectionConfig config =
          planner.getContext().unwrap(CalciteConnectionConfig.class);
      if (config != null && config.forceDecorrelate()) {
        return RelDecorrelator.decorrelateQuery(rel);
      }
      return rel;
    }
  }

  /** Program that trims fields. */
  private static class TrimFieldsProgram implements Program {
    public RelNode run(RelOptPlanner planner, RelNode rel,
        RelTraitSet requiredOutputTraits,
        List<RelOptMaterialization> materializations,
        List<RelOptLattice> lattices) {
      final RelBuilder relBuilder =
          RelFactories.LOGICAL_BUILDER.create(rel.getCluster(), null);
      return new RelFieldTrimmer(null, relBuilder).trim(rel);
    }
  }
}

// End Programs.java
