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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.operator.window.pattern;

import io.trino.operator.project.PageProjection;
import io.trino.operator.window.matcher.ArrayView;
import io.trino.spi.block.Block;
import io.trino.spi.connector.ConnectorSession;

import java.util.List;
import java.util.function.Supplier;

import static io.trino.operator.window.pattern.MeasureComputation.compute;
import static io.trino.operator.window.pattern.MeasureComputation.precomputeNulls;
import static io.trino.spi.type.BooleanType.BOOLEAN;
import static java.util.Objects.requireNonNull;

public class LabelEvaluator
{
    private final long matchNumber;

    private final int patternStart;

    // inclusive - the first row of the search partition
    private final int partitionStart;

    // inclusive - the first row of the partition area available for pattern search.
    // this area is the whole partition in case of MATCH_RECOGNIZE, and the area enclosed
    // by the common base frame in case of pattern recognition in WINDOW clause.
    private final int searchStart;

    // exclusive - the first row after the the partition area available for pattern search.
    // this area is the whole partition in case of MATCH_RECOGNIZE, and the area enclosed
    // by the common base frame in case of pattern recognition in WINDOW clause.
    private final int searchEnd;

    private final List evaluations;

    private final ProjectingPagesWindowIndex windowIndex;

    public LabelEvaluator(long matchNumber, int patternStart, int partitionStart, int searchStart, int searchEnd, List evaluations, ProjectingPagesWindowIndex windowIndex)
    {
        this.matchNumber = matchNumber;
        this.patternStart = patternStart;
        this.partitionStart = partitionStart;
        this.searchStart = searchStart;
        this.searchEnd = searchEnd;
        this.evaluations = requireNonNull(evaluations, "evaluations is null");
        this.windowIndex = requireNonNull(windowIndex, "windowIndex is null");
    }

    public int getInputLength()
    {
        return searchEnd - patternStart;
    }

    public boolean isMatchingAtPartitionStart()
    {
        return patternStart == partitionStart;
    }

    // evaluate the last label in matchedLabels. It has been tentatively appended to the match
    public boolean evaluateLabel(ArrayView matchedLabels, MatchAggregation[] aggregations)
    {
        int label = matchedLabels.get(matchedLabels.length() - 1);
        Evaluation evaluation = evaluations.get(label);
        return evaluation.test(matchedLabels, aggregations, partitionStart, searchStart, searchEnd, patternStart, matchNumber, windowIndex);
    }

    public static class Evaluation
    {
        // compiled computation of label-defining boolean expression
        private final PageProjection projection;

        // value accessors ordered as expected by the compiled projection
        private final List expectedLayout;

        // precomputed `Block`s with null values for every `PhysicalValuePointer` (see MeasureComputation)
        private final Block[] nulls;

        // mapping from int representation to label name
        private final List labelNames;

        private final ConnectorSession session;

        public Evaluation(PageProjection projection, List expectedLayout, List labelNames, ConnectorSession session)
        {
            this.projection = requireNonNull(projection, "projection is null");
            this.expectedLayout = requireNonNull(expectedLayout, "expectedLayout is null");
            this.nulls = precomputeNulls(expectedLayout);
            this.labelNames = requireNonNull(labelNames, "labelNames is null");
            this.session = requireNonNull(session, "session is null");
        }

        public List getExpectedLayout()
        {
            return expectedLayout;
        }

        public boolean test(ArrayView matchedLabels, MatchAggregation[] aggregations, int partitionStart, int searchStart, int searchEnd, int patternStart, long matchNumber, ProjectingPagesWindowIndex windowIndex)
        {
            int currentRow = patternStart + matchedLabels.length() - 1;
            Block result = compute(currentRow, matchedLabels, aggregations, partitionStart, searchStart, searchEnd, patternStart, matchNumber, windowIndex, projection, expectedLayout, nulls, labelNames, session);

            return BOOLEAN.getBoolean(result, 0);
        }
    }

    public static class EvaluationSupplier
    {
        private final Supplier projection;
        private final List expectedLayout;
        private final List labelNames;
        private final ConnectorSession session;

        public EvaluationSupplier(Supplier projection, List expectedLayout, List labelNames, ConnectorSession session)
        {
            this.projection = requireNonNull(projection, "projection is null");
            this.expectedLayout = requireNonNull(expectedLayout, "expectedLayout is null");
            this.labelNames = requireNonNull(labelNames, "labelNames is null");
            this.session = requireNonNull(session, "session is null");
        }

        public Evaluation get()
        {
            return new Evaluation(projection.get(), expectedLayout, labelNames, session);
        }
    }
}