/**
 *    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 "mongo/base/string_data.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/bson/timestamp.h"
#include "mongo/db/pipeline/document.h"
#include "mongo/db/pipeline/value.h"
#include "mongo/util/uuid.h"

namespace mongo {

struct ResumeTokenData {
    ResumeTokenData(){};
    ResumeTokenData(Timestamp clusterTimeIn,
                    Value documentKeyIn,
                    const boost::optional<UUID>& uuidIn)
        : clusterTime(clusterTimeIn), documentKey(std::move(documentKeyIn)), uuid(uuidIn){};

    bool operator==(const ResumeTokenData& other) const;
    bool operator!=(const ResumeTokenData& other) const {
        return !(*this == other);
    };

    Timestamp clusterTime;
    Value documentKey;
    boost::optional<UUID> uuid;
};

std::ostream& operator<<(std::ostream& out, const ResumeTokenData& tokenData);

/**
 * A token passed in by the user to indicate where in the oplog we should start for
 * $changeStream.  This token has the following format:
 * {
 *   _data: <binary data>,
 *   _typeBits: <binary data>
 * }
 * The _data field data is encoded such that byte by byte comparisons provide the correct
 * ordering of tokens.  The _typeBits field may be missing and should not affect token
 * comparison.
 */

class ResumeToken {
public:
    /**
     * The default no-argument constructor is required by the IDL for types used as non-optional
     * fields.
     */
    ResumeToken() = default;

    explicit ResumeToken(const ResumeTokenData& resumeValue);

    bool operator==(const ResumeToken&) const;
    bool operator!=(const ResumeToken&) const;
    bool operator<(const ResumeToken&) const;
    bool operator<=(const ResumeToken&) const;
    bool operator>(const ResumeToken&) const;
    bool operator>=(const ResumeToken&) const;

    /** Three way comparison, returns 0 if *this is equal to other, < 0 if *this is less than
     * other, and > 0 if *this is greater than other.
     */
    int compare(const ResumeToken& other) const;

    Document toDocument() const;

    BSONObj toBSON() const {
        return toDocument().toBson();
    }

    ResumeTokenData getData() const;

    /**
     * Parse a resume token from a BSON object; used as an interface to the IDL parser.
     */
    static ResumeToken parse(const BSONObj& resumeBson) {
        return ResumeToken::parse(Document(resumeBson));
    }

    static ResumeToken parse(const Document& document);

    friend std::ostream& operator<<(std::ostream& out, const ResumeToken& token) {
        return out << token.getData();
    }

    constexpr static StringData kDataFieldName = "_data"_sd;
    constexpr static StringData kTypeBitsFieldName = "_typeBits"_sd;

private:
    explicit ResumeToken(const Document& resumeData);

    Value _keyStringData;
    Value _typeBits;
};
}  // namespace mongo