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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.iterative.rule;

import io.trino.Session;
import io.trino.matching.Capture;
import io.trino.matching.Captures;
import io.trino.matching.Pattern;
import io.trino.metadata.Metadata;
import io.trino.spi.connector.SampleType;
import io.trino.sql.planner.iterative.Rule;
import io.trino.sql.planner.plan.SampleNode;
import io.trino.sql.planner.plan.SampleNode.Type;
import io.trino.sql.planner.plan.TableScanNode;

import java.util.Optional;

import static io.trino.SystemSessionProperties.isAllowPushdownIntoConnectors;
import static io.trino.matching.Capture.newCapture;
import static io.trino.sql.planner.iterative.rule.Rules.deriveTableStatisticsForPushdown;
import static io.trino.sql.planner.plan.Patterns.Sample.sampleType;
import static io.trino.sql.planner.plan.Patterns.sample;
import static io.trino.sql.planner.plan.Patterns.source;
import static io.trino.sql.planner.plan.Patterns.tableScan;
import static io.trino.sql.planner.plan.SampleNode.Type.SYSTEM;

public class PushSampleIntoTableScan
        implements Rule
{
    private static final Capture TABLE_SCAN = newCapture();
    private static final Pattern PATTERN = sample().with(sampleType().equalTo(SYSTEM))
            .with(source().matching(tableScan().capturedAs(TABLE_SCAN)));

    private final Metadata metadata;

    public PushSampleIntoTableScan(Metadata metadata)
    {
        this.metadata = metadata;
    }

    @Override
    public Pattern getPattern()
    {
        return PATTERN;
    }

    @Override
    public boolean isEnabled(Session session)
    {
        return isAllowPushdownIntoConnectors(session);
    }

    @Override
    public Rule.Result apply(SampleNode sample, Captures captures, Rule.Context context)
    {
        TableScanNode tableScan = captures.get(TABLE_SCAN);

        return metadata.applySample(context.getSession(), tableScan.getTable(), getSamplingType(sample.getSampleType()), sample.getSampleRatio())
                .map(result -> Result.ofPlanNode(new TableScanNode(
                        tableScan.getId(),
                        result.getHandle(),
                        tableScan.getOutputSymbols(),
                        tableScan.getAssignments(),
                        tableScan.getEnforcedConstraint(),
                        deriveTableStatisticsForPushdown(context.getStatsProvider(), context.getSession(), result.isPrecalculateStatistics(), sample),
                        tableScan.isUpdateTarget(),
                        // table scan partitioning might have changed with new table handle
                        Optional.empty())))
                .orElseGet(Result::empty);
    }

    private static SampleType getSamplingType(Type sampleNodeType)
    {
        return switch (sampleNodeType) {
            case SYSTEM -> SampleType.SYSTEM;
            case BERNOULLI -> SampleType.BERNOULLI;
        };
    }
}