/**
 *    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.
 */

#pragma once

#include <string>

#include "mongo/base/disallow_copying.h"
#include "mongo/db/jsobj.h"
#include "mongo/util/net/hostandport.h"
#include "mongo/util/time_support.h"

namespace mongo {

    template<typename T> class StatusWith;

    /**
     * Type of object describing a command to execute against a remote MongoDB node.
     */
    struct RemoteCommandRequest {

        // Indicates that there is no timeout for the request to complete
        static const Milliseconds kNoTimeout;

        // Indicates that there is no expiration time by when the request needs to complete
        static const Date_t kNoExpirationDate;

        RemoteCommandRequest() : timeout(kNoTimeout),
                                 expirationDate(kNoExpirationDate) {

        }

        RemoteCommandRequest(const HostAndPort& theTarget,
                             const std::string& theDbName,
                             const BSONObj& theCmdObj,
                             const Milliseconds timeoutMillis = kNoTimeout)
                : target(theTarget),
                  dbname(theDbName),
                  cmdObj(theCmdObj),
                  timeout(timeoutMillis) {

            if (timeoutMillis == kNoTimeout) {
                expirationDate = kNoExpirationDate;
            }
        }

        std::string toString() const;

        HostAndPort target;
        std::string dbname;
        BSONObj cmdObj;
        Milliseconds timeout;

        // Deadline by when the request must be completed
        Date_t expirationDate;
    };


    /**
     * Type of object describing the response of previously sent RemoteCommandRequest.
     */
    struct RemoteCommandResponse {
        RemoteCommandResponse() : data(),
                                  elapsedMillis(Milliseconds(0)) {

        }

        RemoteCommandResponse(BSONObj obj, Milliseconds millis) : data(obj),
                                                                  elapsedMillis(millis) {

        }

        std::string toString() const;

        BSONObj data;
        Milliseconds elapsedMillis;
    };


    /**
     * Abstract interface used for executing commands against a MongoDB instance and retrieving
     * results. It abstracts the logic of managing connections and turns the remote instance into
     * a stateless request-response service.
     */
    class RemoteCommandRunner {
        MONGO_DISALLOW_COPYING(RemoteCommandRunner);
    public:
        virtual ~RemoteCommandRunner() = default;

        /**
         * Synchronously invokes the command described by "request" and returns the server's
         * response or any status.
         */
        virtual StatusWith<RemoteCommandResponse> runCommand(
                                                    const RemoteCommandRequest& request) = 0;

    protected:
        RemoteCommandRunner() = default;
    };

} // namespace mongo