/**
 *    Copyright (C) 2013 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/db/exec/queued_data_stage.h"

#include "mongo/db/exec/scoped_timer.h"
#include "mongo/db/exec/working_set_common.h"

namespace mongo {

using std::unique_ptr;
using std::vector;

const char* QueuedDataStage::kStageType = "QUEUED_DATA";

QueuedDataStage::QueuedDataStage(WorkingSet* ws) : _ws(ws), _commonStats(kStageType) {}

PlanStage::StageState QueuedDataStage::work(WorkingSetID* out) {
    ++_commonStats.works;

    // Adds the amount of time taken by work() to executionTimeMillis.
    ScopedTimer timer(&_commonStats.executionTimeMillis);

    if (isEOF()) {
        return PlanStage::IS_EOF;
    }

    StageState state = _results.front();
    _results.pop();

    if (PlanStage::ADVANCED == state) {
        ++_commonStats.advanced;
        *out = _members.front();
        _members.pop();
    } else if (PlanStage::NEED_TIME == state) {
        ++_commonStats.needTime;
    }

    return state;
}

bool QueuedDataStage::isEOF() {
    return _results.empty();
}

void QueuedDataStage::saveState() {
    ++_commonStats.yields;
}

void QueuedDataStage::restoreState(OperationContext* opCtx) {
    ++_commonStats.unyields;
}

void QueuedDataStage::invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type) {
    ++_commonStats.invalidates;
}

PlanStageStats* QueuedDataStage::getStats() {
    _commonStats.isEOF = isEOF();
    unique_ptr<PlanStageStats> ret(new PlanStageStats(_commonStats, STAGE_QUEUED_DATA));
    ret->specific.reset(new MockStats(_specificStats));
    return ret.release();
}

const CommonStats* QueuedDataStage::getCommonStats() const {
    return &_commonStats;
}

const SpecificStats* QueuedDataStage::getSpecificStats() const {
    return &_specificStats;
}

void QueuedDataStage::pushBack(const PlanStage::StageState state) {
    invariant(PlanStage::ADVANCED != state);
    _results.push(state);
}

void QueuedDataStage::pushBack(const WorkingSetMember& member) {
    _results.push(PlanStage::ADVANCED);

    WorkingSetID id = _ws->allocate();
    WorkingSetMember* ourMember = _ws->get(id);
    WorkingSetCommon::initFrom(ourMember, member);

    // member lives in _ws.  We'll return it when _results hits ADVANCED.
    _members.push(id);
}

vector<PlanStage*> QueuedDataStage::getChildren() const {
    vector<PlanStage*> empty;
    return empty;
}

}  // namespace mongo