/**
 *    Copyright (C) 2012 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.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kSharding

#include "mongo/s/config_upgrade.h"

#include "mongo/client/connpool.h"
#include "mongo/db/write_concern.h"
#include "mongo/s/cluster_client_internal.h"
#include "mongo/s/cluster_write.h"
#include "mongo/s/type_config_version.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"

namespace mongo {

using std::endl;
using std::string;

using mongo::str::stream;

/**
 * Upgrade v0 to v6 described here
 *
 * This upgrade takes the config server from empty to an initial version.
 */
bool doUpgradeV0ToV6(const ConnectionString& configLoc,
                     const VersionType& lastVersionInfo,
                     string* errMsg) {
    string dummy;
    if (!errMsg)
        errMsg = &dummy;

    verify(lastVersionInfo.getCurrentVersion() == UpgradeHistory_EmptyVersion);

    //
    // Even though the initial config write is a single-document update, that single document
    // is on multiple config servers and requests can interleave.  The upgrade lock prevents
    // this.
    //

    log() << "writing initial config version at v" << CURRENT_CONFIG_VERSION << endl;

    OID newClusterId = OID::gen();

    VersionType versionInfo;

    // Upgrade to new version
    versionInfo.setMinCompatibleVersion(MIN_COMPATIBLE_CONFIG_VERSION);
    versionInfo.setCurrentVersion(CURRENT_CONFIG_VERSION);
    versionInfo.setClusterId(newClusterId);

    verify(versionInfo.isValid(NULL));

    // If the cluster has not previously been initialized, we need to set the version before
    // using so subsequent mongoses use the config data the same way.  This requires all three
    // config servers online initially.
    Status result = clusterUpdate(VersionType::ConfigNS,
                                  BSON("_id" << 1),
                                  versionInfo.toBSON(),
                                  true /* upsert */,
                                  false /* multi */,
                                  WriteConcernOptions::AllConfigs,
                                  NULL);

    if (!result.isOK()) {
        *errMsg = stream() << "error writing initial config version: " << result.reason();
        return false;
    }

    return true;
}
}
