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/*    Copyright 2009 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.
 */

#pragma once

#include "mongo/base/data_view.h"
#include "mongo/bson/util/builder.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/time_support.h"

namespace mongo {

    /**
     * Timestamp: A combination of a count of seconds since the POSIX epoch plus an ordinal value.
     */
    class Timestamp {
    public:
        // Maximum Timestamp value.
        static Timestamp max();

        /**
         * DEPRECATED Constructor that builds a Timestamp from a Date_t by using the
         * high-order 4 bytes of "date" for the "secs" field and the low-order 4 bytes
         * for the "i" field.
         */
        explicit Timestamp(Date_t date) : Timestamp(date.toULL()) {}

        /**
         * DEPRECATED Constructor that builds a Timestamp from a 64-bit unsigned integer by using
         * the high-order 4 bytes of "v" for the "secs" field and the low-order 4 bytes for the "i"
         * field."
         */
        explicit Timestamp(unsigned long long v) : Timestamp(v >> 32, v) {}

        Timestamp(Seconds s, unsigned increment) : Timestamp(s.count(), increment) {}

        Timestamp(unsigned a, unsigned b) : i(b), secs(a) {
            dassert(secs <= std::numeric_limits<int>::max());
        }

        Timestamp() : i(0), secs(0) {}

        unsigned getSecs() const {
            return secs;
        }

        unsigned getInc() const {
            return i;
        }

        unsigned long long asULL() const {
            unsigned long long result = secs;
            result <<= 32;
            result |= i;
            return result;
        }
        long long asLL() const {
            return static_cast<long long>(asULL());
        }

        bool isNull() const { return secs == 0; }

        std::string toStringLong() const;

        std::string toStringPretty() const;

        std::string toString() const;

        bool operator==(const Timestamp& r) const {
            return tie() == r.tie();
        }
        bool operator!=(const Timestamp& r) const {
            return tie() != r.tie();
        }
        bool operator<(const Timestamp& r) const {
            return tie() < r.tie();
        }
        bool operator<=(const Timestamp& r) const {
            return tie() <= r.tie();
        }
        bool operator>(const Timestamp& r) const {
            return tie() > r.tie();
        }
        bool operator>=(const Timestamp& r) const {
            return tie() >= r.tie();
        }

        // Append the BSON representation of this Timestamp to the given BufBuilder with the given
        // name. This lives here because Timestamp manages its own serialization format.
        void append(BufBuilder& builder, const StringData& fieldName) const;

    private:
        std::tuple<unsigned, unsigned> tie() const { return std::tie(secs, i); }

        unsigned i; // ordinal comes first so we can do a single 64 bit compare on little endian
        unsigned secs;
    };

} // namespace mongo