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/*
 * Licensed 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 io.trino.sql.planner;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import io.trino.sql.ir.DefaultTraversalVisitor;
import io.trino.sql.ir.Expression;
import io.trino.sql.ir.Lambda;
import io.trino.sql.ir.Reference;
import io.trino.sql.planner.iterative.Lookup;
import io.trino.sql.planner.plan.AggregationNode.Aggregation;
import io.trino.sql.planner.plan.PlanNode;
import io.trino.sql.planner.plan.WindowNode;

import java.util.List;
import java.util.Set;

import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static io.trino.sql.planner.ExpressionExtractor.extractExpressions;
import static io.trino.sql.planner.ExpressionExtractor.extractExpressionsNonRecursive;
import static io.trino.sql.planner.iterative.Lookup.noLookup;
import static io.trino.sql.planner.optimizations.PlanNodeSearcher.searchFrom;

public final class SymbolsExtractor
{
    private SymbolsExtractor() {}

    public static Set extractUnique(PlanNode node)
    {
        ImmutableSet.Builder uniqueSymbols = ImmutableSet.builder();
        extractExpressions(node).forEach(expression -> uniqueSymbols.addAll(extractUnique(expression)));

        return uniqueSymbols.build();
    }

    public static Set extractUniqueNonRecursive(PlanNode node)
    {
        ImmutableSet.Builder uniqueSymbols = ImmutableSet.builder();
        extractExpressionsNonRecursive(node).forEach(expression -> uniqueSymbols.addAll(extractUnique(expression)));

        return uniqueSymbols.build();
    }

    public static Set extractUnique(PlanNode node, Lookup lookup)
    {
        ImmutableSet.Builder uniqueSymbols = ImmutableSet.builder();
        extractExpressions(node, lookup).forEach(expression -> uniqueSymbols.addAll(extractUnique(expression)));

        return uniqueSymbols.build();
    }

    public static Set extractUnique(Expression expression)
    {
        return ImmutableSet.copyOf(extractAll(expression));
    }

    public static Set extractUnique(Iterable expressions)
    {
        ImmutableSet.Builder unique = ImmutableSet.builder();
        for (Expression expression : expressions) {
            unique.addAll(extractAll(expression));
        }
        return unique.build();
    }

    public static Set extractUnique(Aggregation aggregation)
    {
        return ImmutableSet.copyOf(extractAll(aggregation));
    }

    public static Set extractUnique(WindowNode.Function function)
    {
        return ImmutableSet.copyOf(extractAll(function));
    }

    public static List extractAll(Expression expression)
    {
        ImmutableList.Builder builder = ImmutableList.builder();
        new SymbolBuilderVisitor().process(expression, builder);
        return builder.build();
    }

    public static List extractAll(Aggregation aggregation)
    {
        ImmutableList.Builder builder = ImmutableList.builder();
        for (Expression argument : aggregation.getArguments()) {
            builder.addAll(extractAll(argument));
        }
        aggregation.getFilter().ifPresent(builder::add);
        aggregation.getOrderingScheme().ifPresent(orderBy -> builder.addAll(orderBy.orderBy()));
        aggregation.getMask().ifPresent(builder::add);
        return builder.build();
    }

    public static List extractAll(WindowNode.Function function)
    {
        ImmutableList.Builder builder = ImmutableList.builder();
        for (Expression argument : function.getArguments()) {
            builder.addAll(extractAll(argument));
        }
        function.getFrame().getEndValue().ifPresent(builder::add);
        function.getFrame().getSortKeyCoercedForFrameEndComparison().ifPresent(builder::add);
        function.getFrame().getStartValue().ifPresent(builder::add);
        function.getFrame().getSortKeyCoercedForFrameStartComparison().ifPresent(builder::add);
        return builder.build();
    }

    public static Set extractOutputSymbols(PlanNode planNode)
    {
        return extractOutputSymbols(planNode, noLookup());
    }

    public static Set extractOutputSymbols(PlanNode planNode, Lookup lookup)
    {
        return searchFrom(planNode, lookup)
                .findAll()
                .stream()
                .flatMap(node -> node.getOutputSymbols().stream())
                .collect(toImmutableSet());
    }

    private static class SymbolBuilderVisitor
            extends DefaultTraversalVisitor>
    {
        @Override
        protected Void visitReference(Reference node, ImmutableList.Builder builder)
        {
            builder.add(Symbol.from(node));
            return null;
        }

        @Override
        protected Void visitLambda(Lambda node, ImmutableList.Builder context)
        {
            // Symbols in lambda expression are bound to lambda arguments, so no need to extract them
            return null;
        }
    }
}