/**
 * Copyright (c) 2011 10gen Inc.
 *
 * This program is free software: you can redistribute it and/or  modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * As a special exception, the copyright holders give permission to link the
 * code of portions of this program with the OpenSSL library under certain
 * conditions as described in each individual source file and distribute
 * linked combinations including the program with the OpenSSL library. You
 * must comply with the GNU Affero General Public License in all respects for
 * all of the code used other than as permitted herein. If you modify file(s)
 * with this exception, you may extend this exception to your version of the
 * file(s), but you are not obligated to do so. If you do not wish to do so,
 * delete this exception statement from your version. If you delete this
 * exception statement from all source files in the program, then also delete
 * it in the license file.
 */

#include "mongo/pch.h"

#include "mongo/db/pipeline/accumulator.h"
#include "mongo/db/pipeline/value.h"

namespace mongo {

    void AccumulatorMinMax::processInternal(const Value& input, bool merging) {
        // nullish values should have no impact on result
        if (!input.nullish()) {
            /* compare with the current value; swap if appropriate */
            int cmp = Value::compare(_val, input) * _sense;
            if (cmp > 0 || _val.missing()) { // missing is lower than all other values
                _val = input;
                _memUsageBytes = sizeof(*this) + input.getApproximateSize() - sizeof(Value);
            }
        }
    }

    Value AccumulatorMinMax::getValue(bool toBeMerged) const {
        return _val;
    }

    AccumulatorMinMax::AccumulatorMinMax(int theSense)
        :_sense(theSense)
    {
        verify((_sense == 1) || (_sense == -1));
        _memUsageBytes = sizeof(*this);
    }

    void AccumulatorMinMax::reset() {
        _val = Value();
        _memUsageBytes = sizeof(*this);
    }

    intrusive_ptr<Accumulator> AccumulatorMinMax::createMin() {
        return new AccumulatorMinMax(1);
    }

    intrusive_ptr<Accumulator> AccumulatorMinMax::createMax() {
        return new AccumulatorMinMax(-1);
    }

    const char *AccumulatorMinMax::getOpName() const {
        if (_sense == 1)
            return "$min";
        return "$max";
    }
}