/**
 *    Copyright (C) 2015 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.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kCommand

#include "mongo/platform/basic.h"

#include <string>
#include <vector>

#include "mongo/client/connpool.h"
#include "mongo/db/commands.h"
#include "mongo/db/operation_context.h"
#include "mongo/s/catalog/catalog_manager.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/grid.h"
#include "mongo/s/client/shard.h"
#include "mongo/util/log.h"

namespace mongo {

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

namespace {

    class RemoveShardCmd : public Command {
    public:
        RemoveShardCmd() : Command("removeShard", false, "removeshard") { }

        virtual bool slaveOk() const {
            return true;
        }

        virtual bool adminOnly() const {
            return true;
        }

        virtual bool isWriteCommandForConfigServer() const {
            return false;
        }

        virtual void help(std::stringstream& help) const {
            help << "remove a shard from the system.";
        }

        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {

            ActionSet actions;
            actions.addAction(ActionType::removeShard);
            out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
        }

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

            const string target = cmdObj.firstElement().valuestrsafe();

            const auto& s = grid.shardRegistry()->findIfExists(target);
            if (!s) {
                string msg(str::stream() <<
                           "Could not drop shard '" << target <<
                           "' because it does not exist");
                log() << msg;
                return appendCommandStatus(result,
                                           Status(ErrorCodes::ShardNotFound, msg));
            }

            StatusWith<ShardDrainingStatus> removeShardResult =
                grid.catalogManager()->removeShard(txn, s->getId());
            if (!removeShardResult.isOK()) {
                return appendCommandStatus(result, removeShardResult.getStatus());
            }

            vector<string> databases;
            grid.catalogManager()->getDatabasesForShard(s->getId(), &databases);

            // Get BSONObj containing:
            // 1) note about moving or dropping databases in a shard
            // 2) list of databases (excluding 'local' database) that need to be moved
            BSONObj dbInfo;
            {
                BSONObjBuilder dbInfoBuilder;
                dbInfoBuilder.append("note",
                                     "you need to drop or movePrimary these databases");
                BSONArrayBuilder dbs(dbInfoBuilder.subarrayStart("dbsToMove"));
                for (vector<string>::const_iterator it = databases.begin();
                     it != databases.end();
                     it++) {
                    if (*it != "local") {
                        dbs.append(*it);
                    }
                }
                dbs.doneFast();
                dbInfo = dbInfoBuilder.obj();
            }

            // TODO: Standardize/Seperate how we append to the result object
            switch (removeShardResult.getValue()) {
            case ShardDrainingStatus::STARTED:
                result.append("msg", "draining started successfully");
                result.append("state", "started");
                result.append("shard", s->getId());
                result.appendElements(dbInfo);
                break;
            case ShardDrainingStatus::ONGOING: {
                vector<ChunkType> chunks;
                Status status = grid.catalogManager()->getChunks(
                                            Query(BSON(ChunkType::shard(s->getId()))),
                                            0,  // return all
                                            &chunks);
                if (!status.isOK()) {
                    return appendCommandStatus(result, status);
                }

                result.append("msg", "draining ongoing");
                result.append("state", "ongoing");
                {
                    BSONObjBuilder inner;
                    inner.append("chunks", static_cast<long long>(chunks.size()));
                    inner.append("dbs", static_cast<long long>(databases.size()));
                    BSONObj b = inner.obj();
                    result.append("remaining", b);
                }
                result.appendElements(dbInfo);
                break;
            }
            case ShardDrainingStatus::COMPLETED:
                result.append("msg", "removeshard completed successfully");
                result.append("state", "completed");
                result.append("shard", s->getId());
            }

            return true;
        }

    } removeShardCmd;

} // namespace
} // namespace mongo