/*
 ***************************************************************************************
 *  Copyright (C) 2006 EsperTech, Inc. All rights reserved.                            *
 *  http://www.espertech.com/esper                                                     *
 *  http://www.espertech.com                                                           *
 *  ---------------------------------------------------------------------------------- *
 *  The software in this package is published under the terms of the GPL license       *
 *  a copy of which has been included with this distribution in the license.txt file.  *
 ***************************************************************************************
 */
package com.espertech.esper.epl.expression.subquery;

import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.agg.service.AggregationService;
import com.espertech.esper.epl.expression.core.ExprEvaluator;
import com.espertech.esper.epl.expression.core.ExprEvaluatorContext;
import com.espertech.esper.type.RelationalOpEnum;

import java.util.Collection;

public class SubselectEvalStrategyNRRelOpAllWGroupBy extends SubselectEvalStrategyNRRelOpBase {

    private final ExprEvaluator havingEval;

    public SubselectEvalStrategyNRRelOpAllWGroupBy(ExprEvaluator valueEval, ExprEvaluator selectEval, boolean resultWhenNoMatchingEvents, RelationalOpEnum.Computer computer, ExprEvaluator havingEval) {
        super(valueEval, selectEval, resultWhenNoMatchingEvents, computer);
        this.havingEval = havingEval;
    }

    protected Object evaluateInternal(Object leftResult, EventBean[] events, boolean isNewData, Collection<EventBean> matchingEvents, ExprEvaluatorContext exprEvaluatorContext, AggregationService aggregationServiceAnyPartition) {
        AggregationService aggregationService = aggregationServiceAnyPartition.getContextPartitionAggregationService(exprEvaluatorContext.getAgentInstanceId());
        Collection<Object> groupKeys = aggregationService.getGroupKeys(exprEvaluatorContext);
        boolean hasRows = false;
        boolean hasNullRow = false;

        for (Object groupKey : groupKeys) {
            aggregationService.setCurrentAccess(groupKey, exprEvaluatorContext.getAgentInstanceId(), null);
            if (havingEval != null) {
                Boolean pass = (Boolean) havingEval.evaluate(events, true, exprEvaluatorContext);
                if ((pass == null) || (!pass)) {
                    continue;
                }
            }
            hasRows = true;

            Object valueRight;
            if (selectEval != null) {
                valueRight = selectEval.evaluate(events, true, exprEvaluatorContext);
            } else {
                valueRight = events[0].getUnderlying();
            }

            if (valueRight == null) {
                hasNullRow = true;
            } else {
                if (leftResult != null) {
                    if (!computer.compare(leftResult, valueRight)) {
                        return false;
                    }
                }
            }
        }

        if (!hasRows) {
            return true;
        }
        if (leftResult == null) {
            return null;
        }
        if (hasNullRow) {
            return null;
        }
        return true;
    }
}