/**
 *    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/base/init.h"
#include "mongo/db/auth/action_type.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/auth/privilege.h"
#include "mongo/db/commands.h"
#include "mongo/db/field_parser.h"
#include "mongo/db/namespace_string.h"
#include "mongo/s/d_state.h"
#include "mongo/s/d_merge.h"

namespace mongo {

using std::string;
using std::stringstream;
using std::vector;

/**
 * Mongod-side command for merging chunks.
 */
class MergeChunksCommand : public Command {
public:
    MergeChunksCommand() : Command("mergeChunks") {}

    virtual void help(stringstream& h) const {
        h << "Merge Chunks command\n"
          << "usage: { mergeChunks : <ns>, bounds : [ <min key>, <max key> ],"
          << " (opt) epoch : <epoch>, (opt) config : <configdb string>,"
          << " (opt) shardName : <shard name> }";
    }

    virtual Status checkAuthForCommand(ClientBasic* client,
                                       const std::string& dbname,
                                       const BSONObj& cmdObj) {
        if (!client->getAuthorizationSession()->isAuthorizedForActionsOnResource(
                ResourcePattern::forExactNamespace(NamespaceString(parseNs(dbname, cmdObj))),
                ActionType::splitChunk)) {
            return Status(ErrorCodes::Unauthorized, "Unauthorized");
        }
        return Status::OK();
    }

    virtual std::string parseNs(const std::string& dbname, const BSONObj& cmdObj) const {
        return parseNsFullyQualified(dbname, cmdObj);
    }

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

    // Required
    static BSONField<string> nsField;
    static BSONField<vector<BSONObj>> boundsField;
    // Optional, if the merge is only valid for a particular epoch
    static BSONField<OID> epochField;
    // Optional, if our sharding state has not previously been initializeed
    static BSONField<string> shardNameField;
    static BSONField<string> configField;

    bool run(OperationContext* txn,
             const string& dbname,
             BSONObj& cmdObj,
             int,
             string& errmsg,
             BSONObjBuilder& result,
             bool) {
        string ns = parseNs(dbname, cmdObj);

        if (ns.size() == 0) {
            errmsg = "no namespace specified";
            return false;
        }

        vector<BSONObj> bounds;
        if (!FieldParser::extract(cmdObj, boundsField, &bounds, &errmsg)) {
            return false;
        }

        if (bounds.size() == 0) {
            errmsg = "no bounds were specified";
            return false;
        }

        if (bounds.size() != 2) {
            errmsg = "only a min and max bound may be specified";
            return false;
        }

        BSONObj minKey = bounds[0];
        BSONObj maxKey = bounds[1];

        if (minKey.isEmpty()) {
            errmsg = "no min key specified";
            return false;
        }

        if (maxKey.isEmpty()) {
            errmsg = "no max key specified";
            return false;
        }

        //
        // This might be the first call from mongos, so we may need to pass the config and shard
        // information to initialize the shardingState.
        //

        string config;
        FieldParser::FieldState extracted =
            FieldParser::extract(cmdObj, configField, &config, &errmsg);
        if (!extracted)
            return false;
        if (extracted != FieldParser::FIELD_NONE) {
            ShardingState::initialize(config);
        } else if (!shardingState.enabled()) {
            errmsg = "sharding state must be enabled or config server specified to merge chunks";
            return false;
        }

        // ShardName is optional, but might not be set yet
        string shardName;
        extracted = FieldParser::extract(cmdObj, shardNameField, &shardName, &errmsg);

        if (!extracted)
            return false;
        if (extracted != FieldParser::FIELD_NONE) {
            shardingState.gotShardName(shardName);
        }

        //
        // Epoch is optional, and if not set indicates we should use the latest epoch
        //

        OID epoch;
        if (!FieldParser::extract(cmdObj, epochField, &epoch, &errmsg)) {
            return false;
        }

        return mergeChunks(txn, NamespaceString(ns), minKey, maxKey, epoch, &errmsg);
    }
};

BSONField<string> MergeChunksCommand::nsField("mergeChunks");
BSONField<vector<BSONObj>> MergeChunksCommand::boundsField("bounds");

BSONField<string> MergeChunksCommand::configField("config");
BSONField<string> MergeChunksCommand::shardNameField("shardName");
BSONField<OID> MergeChunksCommand::epochField("epoch");

MONGO_INITIALIZER(InitMergeChunksCommand)(InitializerContext* context) {
    // Leaked intentionally: a Command registers itself when constructed.
    new MergeChunksCommand();
    return Status::OK();
}
}
