/**
 *    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.
 */

#pragma once

#include "mongo/db/clientcursor.h"
#include "mongo/db/query/canonical_query.h"
#include "mongo/db/query/lite_parsed_query.h"
#include "mongo/db/query/plan_cache.h"
#include "mongo/db/query/plan_executor.h"
#include "mongo/db/query/runner.h"
#include "mongo/db/query/stage_builder.h"

namespace mongo {

    /**
     * SingleSolutionRunner runs a plan that was the only possible solution to a query.  It exists
     * only to dump stats into the cache after running.
     */
    class SingleSolutionRunner : public Runner {
    public:
        /**
         * Takes ownership of both arguments.
         */
        SingleSolutionRunner(CanonicalQuery* canonicalQuery, QuerySolution* soln,
                             PlanStage* root, WorkingSet* ws)
            : _canonicalQuery(canonicalQuery), _solution(soln),
              _exec(new PlanExecutor(ws, root)) { }

        Runner::RunnerState getNext(BSONObj* objOut, DiskLoc* dlOut) {
            return _exec->getNext(objOut, dlOut);
            // TODO: I'm not convinced we want to cache this run.  What if it's a collscan solution
            // and the user adds an index later?  We don't want to reach for this.  But if solving
            // the query is v. hard, we do want to cache it.  Maybe we can remove single solution
            // cache entries when we build an index?
        }

        virtual bool isEOF() { return _exec->isEOF(); }

        virtual void saveState() { _exec->saveState(); }

        virtual bool restoreState() { return _exec->restoreState(); }

        virtual void setYieldPolicy(Runner::YieldPolicy policy) {
            _exec->setYieldPolicy(policy);
        }

        virtual void invalidate(const DiskLoc& dl) { _exec->invalidate(dl); }

        virtual const string& ns() { return _canonicalQuery->getParsed().ns(); }

        virtual void kill() { _exec->kill(); }

    private:
        scoped_ptr<CanonicalQuery> _canonicalQuery;
        scoped_ptr<QuerySolution> _solution;
        scoped_ptr<PlanExecutor> _exec;
    };

}  // namespace mongo