/**
 *    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 "mongo/base/status_with.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/bsonelement.h"
#include "mongo/bson/bsonmisc.h"

#include <stdexcept>
#include <string>

#ifndef _WIN32
#include <sys/socket.h>
#endif

namespace mongo {

/**
 * CIDR (Classless Inter-Domain Routing)
 */
class CIDR {
public:
    explicit CIDR(StringData);

    /**
     * If the given BSONElement represents a valid CIDR range,
     * constructs and returns the CIDR.
     * Otherwise returns an error.
     */
    static StatusWith<CIDR> parse(BSONElement from) noexcept;

    /**
     * If the given string represents a valid CIDR range,
     * constructs and returns the CIDR.
     * Otherwise returns an error.
     */
    static StatusWith<CIDR> parse(StringData from) noexcept;

    /**
     * Returns true if the provided address range is contained
     * entirely within this one, false otherwise.
     */
    bool contains(const CIDR& cidr) const {
        if ((_family != cidr._family) || (_len > cidr._len)) {
            return false;
        }

        auto bytes = _len / 8;
        auto const range = _ip.begin();
        auto const ip = cidr._ip.begin();
        if (!std::equal(range, range + bytes, ip, ip + bytes)) {
            return false;
        }

        if ((_len % 8) == 0) {
            return true;
        }

        auto mask = (0xFF << (8 - (_len % 8))) & 0xFF;
        return (_ip[bytes] & mask) == (cidr._ip[bytes] & mask);
    }

    friend bool operator==(const CIDR& lhs, const CIDR& rhs);
    friend bool operator!=(const CIDR& lhs, const CIDR& rhs) {
        return !(lhs == rhs);
    }
    friend std::ostream& operator<<(std::ostream& s, const CIDR& rhs);
    friend StringBuilder& operator<<(StringBuilder& s, const CIDR& rhs);

    /**
     * Return a string representation of this CIDR (i.e. "169.254.0.0/16")
     */
    std::string toString() const {
        StringBuilder s;
        s << *this;
        return s.str();
    }

private:
#ifdef _WIN32
    using sa_family_t = int;
#endif

    auto equalityLens() const {
        return std::tie(_ip, _family, _len);
    }

    std::array<std::uint8_t, 16> _ip;
    sa_family_t _family;
    std::uint8_t _len;
};

inline bool operator==(const CIDR& lhs, const CIDR& rhs) {
    return lhs.equalityLens() == rhs.equalityLens();
}

std::ostream& operator<<(std::ostream& s, const CIDR& cidr);
StringBuilder& operator<<(StringBuilder& s, const CIDR& cidr);

/**
 * Supports use of CIDR with the BSON macro:
 *     BSON("cidr" << cidr) -> { cidr: "..." }
 */
template <>
BSONObjBuilder& BSONObjBuilderValueStream::operator<<<CIDR>(CIDR value);

}  // namespace mongo