/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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/platform/basic.h"

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

#include "mongo/db/pipeline/accumulation_statement.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/value.h"

namespace mongo {

using boost::intrusive_ptr;
using std::vector;

REGISTER_ACCUMULATOR(push, AccumulatorPush::create);

const char* AccumulatorPush::getOpName() const {
    return "$push";
}

void AccumulatorPush::processInternal(const Value& input, bool merging) {
    if (!merging) {
        if (!input.missing()) {
            vpValue.push_back(input);
            _memUsageBytes += input.getApproximateSize();
        }
    } else {
        // If we're merging, we need to take apart the arrays we
        // receive and put their elements into the array we are collecting.
        // If we didn't, then we'd get an array of arrays, with one array
        // from each merge source.
        verify(input.getType() == Array);

        const vector<Value>& vec = input.getArray();
        vpValue.insert(vpValue.end(), vec.begin(), vec.end());

        for (size_t i = 0; i < vec.size(); i++) {
            _memUsageBytes += vec[i].getApproximateSize();
        }
    }
}

Value AccumulatorPush::getValue(bool toBeMerged) {
    return Value(vpValue);
}

AccumulatorPush::AccumulatorPush(const boost::intrusive_ptr<ExpressionContext>& expCtx)
    : Accumulator(expCtx) {
    _memUsageBytes = sizeof(*this);
}

void AccumulatorPush::reset() {
    vector<Value>().swap(vpValue);
    _memUsageBytes = sizeof(*this);
}

intrusive_ptr<Accumulator> AccumulatorPush::create(
    const boost::intrusive_ptr<ExpressionContext>& expCtx) {
    return new AccumulatorPush(expCtx);
}
}