/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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 <boost/optional.hpp>
#include <memory>
#include <string>

#include "mongo/base/disallow_copying.h"
#include "mongo/rpc/metadata/client_metadata.h"

namespace mongo {

class Client;

/**
 * ClientMetadataIsMasterState is responsible for tracking whether the client metadata document has
 * been received by the specified Client object.
 */
class ClientMetadataIsMasterState {
    MONGO_DISALLOW_COPYING(ClientMetadataIsMasterState);

public:
    ClientMetadataIsMasterState() = default;

    static ClientMetadataIsMasterState& get(Client* client);

    /**
     * Get the optional client metadata object.
     */
    const boost::optional<ClientMetadata>& getClientMetadata() const;

    /**
     * Set the optional client metadata object.
     */
    static void setClientMetadata(Client* client,
                                  boost::optional<ClientMetadata> clientMetadata,
                                  bool setViaMetadata = false);

    /**
     * Check a flag to indicate that isMaster has been seen for this Client.
     */
    bool hasSeenIsMaster() const;

    /**
     * Set a flag to indicate that isMaster has been seen for this Client.
     */
    void setSeenIsMaster();

    /**
     * Read from the $client field in requests.
     *
     * Returns an error if the $client section is not valid. It is valid for it to not exist though.
     *
     * Thread-Safety:
     *   None - must be only be read and written from the thread owning "Client".
     */
    static Status readFromMetadata(OperationContext* opCtx, BSONElement& elem);

    /**
     * Write the $client section to request bodies if there is a non-empty client metadata
     * connection with the current client.
     *
     * Thread-Safety:
     *   None - must be only be read and written from the thread owning "Client".
     */
    static void writeToMetadata(OperationContext* opCtx, BSONObjBuilder* builder);

private:
    // Optional client metadata document.
    // Set if client sees isMaster cmd or the $client field.
    // Thread-Safety:
    //   Can be read and written from the thread owning "Client".
    //   Can be read from other threads if they hold the "Client" lock.
    boost::optional<ClientMetadata> _clientMetadata{boost::none};

    // Indicates whether we have seen an is master for this client.
    // Thread-Safety:
    //   None - must be only be read and written from the thread owning "Client".
    bool _hasSeenIsMaster{false};

    // Indicates whether we have set isMaster based on metadata or via isMaster
    // Thread-Safety:
    //   None - must be only be read and written from the thread owning "Client".
    bool _setViaMetadata{false};
};

}  // namespace mongo