// repair_cursor.cpp

/**
*    Copyright (C) 2014 MongoDB 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/platform/basic.h"

#include <memory>

#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/exec/multi_iterator.h"
#include "mongo/db/query/cursor_responses.h"

namespace mongo {

    using std::string;

    class RepairCursorCmd : public Command {
    public:
        RepairCursorCmd() : Command("repairCursor") {}

        virtual bool isWriteCommandForConfigServer() const { return false; }
        virtual bool slaveOk() const { return true; }

        virtual Status checkAuthForCommand(ClientBasic* client,
                                           const std::string& dbname,
                                           const BSONObj& cmdObj) {
            ActionSet actions;
            actions.addAction(ActionType::find);
            Privilege p(parseResourcePattern(dbname, cmdObj), actions);
            if (AuthorizationSession::get(client)->isAuthorizedForPrivilege(p))
                return Status::OK();
            return Status(ErrorCodes::Unauthorized, "Unauthorized");
        }

        virtual bool run(OperationContext* txn,
                         const string& dbname,
                         BSONObj& cmdObj,
                         int options,
                         string& errmsg,
                         BSONObjBuilder& result) {

            NamespaceString ns(parseNs(dbname, cmdObj));

            AutoGetCollectionForRead ctx(txn, ns.ns());

            Collection* collection = ctx.getCollection();
            if (!collection) {
                return appendCommandStatus(result,
                                           Status(ErrorCodes::NamespaceNotFound,
                                                  "ns does not exist: " + ns.ns()));
            }

            auto cursor = collection->getRecordStore()->getCursorForRepair(txn);
            if (!cursor) {
                return appendCommandStatus(result,
                                           Status(ErrorCodes::CommandNotSupported,
                                                  "repair iterator not supported"));
            }

            std::unique_ptr<WorkingSet> ws(new WorkingSet());
            std::unique_ptr<MultiIteratorStage> stage(new MultiIteratorStage(txn, ws.get(),
                                                                           collection));
            stage->addIterator(std::move(cursor));

            PlanExecutor* rawExec;
            Status execStatus = PlanExecutor::make(txn,
                                                   ws.release(),
                                                   stage.release(),
                                                   collection,
                                                   PlanExecutor::YIELD_AUTO,
                                                   &rawExec);
            invariant(execStatus.isOK());
            std::unique_ptr<PlanExecutor> exec(rawExec);

            // 'exec' will be used in getMore(). It was automatically registered on construction
            // due to the auto yield policy, so it could yield during plan selection. We deregister
            // it now so that it can be registed with ClientCursor.
            exec->deregisterExec();
            exec->saveState();

            // ClientCursors' constructor inserts them into a global map that manages their
            // lifetimes. That is why the next line isn't leaky.
            ClientCursor* cc = new ClientCursor(collection->getCursorManager(),
                                                exec.release(),
                                                ns.ns());

            appendCursorResponseObject(cc->cursorid(), ns.ns(), BSONArray(), &result);

            return true;

        }
    } repairCursorCmd;

}